May 2, 2024

In "H5N1: An Impending Crisis," Dr. Osterholm and Chris Dall discuss the spread of H5N1 avian influenza in US
dairy cows, cover the latest COVID-19 trends, review two articles on long COVID, and answers a listener question about the safety of raw milk and other dairy products. Dr. Osterholm also shares a timely "This Week in Public Health History" segment and interviews the final two members of the podcast team.



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Episode 156 Transcript

Chris Dall: Hello and welcome to the Osterholm update, a podcast on COVID-19 and other infectious diseases with Dr. Michael Osterholm. Dr. Osterholm is an internationally recognized medical detective and director of the center for Infectious Disease Research and Policy, or CIDRAP, at the University of Minnesota. In this podcast, Doctor Osterholm draws on nearly 50 years of experience investigating infectious disease outbreaks to provide straight talk on the latest infectious disease and public health threats. I'm Chris Dall, reporter for CIDRAP news, and I'm your host for these conversations. Welcome back, everyone, to another episode of The Osterholm Update podcast. While COVID-19 has always been the focus of this podcast, we've been tracking, providing updates and answering questions about a variety of infectious diseases more and more. As the urgency of the pandemic has waned over the past two years, we've provided information on flu and respiratory syncytial virus, measles, m-pox, chronic wasting disease, and avian influenza, just to name a few. To date, none of these issues have moved COVID out of the spotlight. But in the two weeks since our last episode, the spread of H5N1 avian influenza in US dairy cows has changed that dynamic. So on this May 2nd episode of the podcast, that's where we're going to start. What does the detection of genetic fragments of H5N1 and US dairy samples tell us about this virus, and what does it mean from a public health perspective? Of course, we'll also give you an update on the status of COVID-19 here in the United States and elsewhere, and discuss some of the latest news on long COVID. We'll also answer an ID query on the US milk supply, bringing you a timely installment of This Week in Public Health history, and share our latest segment marking the four-year anniversary of the podcast. But before we get started, as always, we'll begin with Doctor Osterholm's opening comments and dedication.


Michael Osterholm: Thanks, Chris, and welcome back to all the podcast family members. We're so glad to have you with us. If you're listening to this podcast for the first time or have only listened to occasionally, I hope we're able to provide you with what you're looking for today in terms of information regarding COVID. But as Chris just noted, a number of other very topical areas. Let me start right out of the chute with the dedication, because I think it really speaks to where we're at right now as a nation where I know we surely are as a scientific community. It's hard to believe it's already May, but we're here and oh, do I love it. I love the month of May and as you may or may not already know, May is also important for another reason. It's Mental Health Awareness Month since 1949. This month has served to reduce the stigma of mental health, to educate people about available services, and to advocate for research and policies that improve the lives of individuals affected by mental illness. This is such an important issue. The National Alliance of Mental Health reports that 1 in 5 US adults experience mental illness, and that 50% of all lifetime mental illness conditions begin before the age of 14. I know in my own family, among my friends and colleagues, I can attest to the fact that these numbers are real. The average delay between onset of mental illness symptoms and treatment is 11 years, which only highlights the importance of campaigns such as Mental Health Awareness Month, which provides education on mental health topics and helps individuals connect to care.


Michael Osterholm: Whether you've dealt with mental health issues personally or you know someone who has, this is something that touches each of us. In fact, it was about a year ago that Doctor Vivek Murthy, the Surgeon General, declared mental health a defining public health crisis of our time. Since we're a podcast that mostly covers infectious disease issues, I thought I'd bring that into the conversation as well. The COVID-19 pandemic affected all of us in so many ways, including increased isolation, worry, stress, and clearly lots of grief. And of course, my mind goes to those dealing with long COVID, whose long-lasting symptoms can have devastating effects on their mental health and that of their caregivers. I know that this is a heavy way to start the podcast, so I want to share some hope that I see. And that's all the public health research and work that's being done today to address and mitigate the effects of mental health in our society. For example, the research that's being conducted on long COVID, which will hopefully alleviate the physical and mental burden of those dealing with chronic symptoms, or a new study published earlier this week suggesting that increasing physical activity in schools is an effective intervention against mental health disorders and children. College campuses are tackling this issue with training and programs to help faculty and students recognize the signs of mental distress, and others could not be more timely given what we're seeing happen in our college campuses around the country. While there's still a long way to go and a lot to do, I find hope in the innovation and dedication of the researchers and practitioners of the mental health field.


Michael Osterholm: So for this first episode in the month of May, Mental Health Awareness Month, I'd like to dedicate this podcast to all those who deal with mental illness in their own lives, as well as the researchers and practitioners who work in the field of mental health, and who are dedicated to the improvement of services and resources for those who are struggling. We appreciate your contributions and hope to see a day when less people have to suffer without access to care and support. Well, now, moving from that very sincere dedication, let me take us to a bright spot. Yep, that light thing. And today in Minneapolis, sunrise is at 6 a.m., sunset at 820 for 14 hours, 20 minutes, and 27 seconds of sunlight. We're gaining at about two minutes and 41 seconds a day, and we still have more than an hour and 16 minutes more of sunlight to appreciate. Uh, coming down the pike before we get to June 20th and to our dear friends in Auckland, particularly those at the Occidental Belgian Beer House on Vulcan Lane. Uh, your sunrise today is at 701. Your sun sets at 534. You've got ten hours, 32 minutes, and 59 seconds of sunlight. Yep. You're losing it about a minute and 56 seconds a day. But again, as I've pointed out, we're happy to share it with you. So for all those in North America or anywhere in the Northern Hemisphere, enjoy these long, longer days of summer.


Chris Dall: So, Mike, I must admit it feels a little weird to not start off with COVID, but here we are. Last week, the FDA announced that PCR testing had found remnants of H5N1 avian influenza in 1 in 5 retail milk samples. A group from Ohio State reported finding remnants of the virus in 40% of samples. And those were just two headlines from what was a very busy week on the H5N1 front. And that's continued into this week. So here's my question. What do we know? What don't we know, and what do we need to know about the spread of H5N1 in dairy cows?


Michael Osterholm: Well, Chris, first of all, let me start out by saying, since this podcast has to be somewhat under an hour, an hour and a half, I can't get into all the things we don't know because that might take me the rest of the day. But let me just again reaffirm for you that we do know some very important things about what's happening. Let me go back and remind everyone of what I talked about in the previous podcast about the history of H5N1. Remember that influenza viruses have their natural reservoir or where they live is in aquatic birds. From there, we see spillover from time to time into other animal species and have through all of time. This is because the birds have a very specific receptor site for influenza virus it differs from that of human viruses and the human lungs. Now, what we've typically seen in the past has been this ongoing activity in birds, with only limited impact on other bird species beyond the aquatic birds. Well, that changed back in the 1990s when we began to see what we call high path avian influenza viruses emerge in bird populations and start to spread occasionally to humans, meaning that the virus had to undergo some changes in its genetics to be able to be infectious to a human, and then for a human to transmit it to others. And remember the three viruses that we have historically considered human influenza A virus challenges are H1, H2, and H3.


Michael Osterholm: The hemagglutinin types that infect humans. But in 1996 it was only a phenomenon seen in birds. In 1997, we had a limited outbreak that occurred in the markets of Hong Kong, uh, with 22 cases of infection in humans. The markets in Hong Kong were completely cleaned out of the birds. Uh, the same was true for farms raising those birds in the Guangdong province of China. And lo and behold, it was declared we had stopped a new pandemic virus from emerging. Well, that went on until the end of 2002, early 2003, when we then began to see activity throughout parts of Southeast Asia and China, of H5N1 in birds, and a spillover into humans with up to 100 to 114 cases a year during that period of 2003, four, five, six, and seven. In each instance, we saw transmission to humans with no evidence of ongoing transmission from an infected human to another human. That was good news. Yes, it was challenging. Could it become the pandemic virus of the future? Surely possible, but at least no activity that supported ongoing transmission in humans. And then from 2006 7 to 2014, we continued to see the number of human cases [00:10:00] of H5N1 spilling over from birds to humans dropping year by year, such that by the time we got to 2014, we had 39 human cases that year throughout the world. And then, for reasons we don't know why, in 20 1415, we saw a major increase in activity in the Nile River valley, of which 145 cases occurred, primarily in Egypt, among duck farmers.


Michael Osterholm: Again, no evidence of ongoing transmission from human to human. Why this spilled over, as it did, we don't know. And then it literally disappeared. It just tanked. And between 2017 and 2023, we only had a total of 26 cases, of which 14 were from 2017 to 22. Very, very limited activity. And that has continued to be what we're seeing. But what does that mean in terms of what's happening right now in the animal kingdom? Well, as you know, we now have literally 200 species of animals who have been infected by this new H5N1 that emerged over the past several years. Uh, it has been deadly in a number of animal species. And, of course, now we're seeing it in dairy cattle here in the United States. And it's possible it's also in beef production animals. It's just at this point, we have done limited testing based on what we're seeing right now and the activity of the past several years, despite widespread transmission in animal species. With this new H5N1, we're just not seeing major spillover activity into humans. And this is why the W.H.O. and the CDC continues to state that this is likely a low-risk situation for human illness. Now, that's the background. That's where we come from on this. And again, this virus will literally have to undergo major genetic changes before it could become a virus transmitted readily to humans and then human to human, which would be all precursors to having a human pandemic.


Michael Osterholm: So what do we know right now? What's happening? Well, amongst all the animal species that have been infected, it appears that there was a spillover from wild birds or domestic. Poultry that had been infected by wild birds, likely in the panhandle of Texas. I think that still really needs to be confirmed. It's clear that we picked it up there first. I'm not completely sure yet that that's actually the point of origin, but since that time, we have now seen evidence of this infection in 36 herds in nine states, and that number will continue to increase. I think that this number of animal herds, all milking dairy cattle in these nine states, which can be linked together either by movement of cattle from Texas to a farm or the movement of certain pieces of equipment that may have been contaminated. Is this the entire activity we're seeing? I don't believe that's the case at all. Over the course of the last week, we've had increasing evidence come forward where we're picking up by PCR, which remember, this particular test only picks up a part of the virus, not whole live virus, but we're seeing it widespread in milk sheds throughout the United States. I think when this is all said and done, this really saturated much of North America over the course of the past 3 or 4 months.


Michael Osterholm: When did this jump occur? Well, what I just noted about 3 or 4 months, it appears it may have happened at the end of last year, and since that time we have seen very, very little evidence of any real challenge to human health. We have one case on a farm in Texas where someone has an eye infection, conjunctivitis, which we know humans do have the virus receptor for the avian bird viruses in our eye. And that wouldn't be a surprise then to see that happen. But in fact, we have no evidence of influenza-like illness. We have no evidence of anyone transmitting the virus from one person to another. And so I think at this point, one, that this still poses a low risk for human infection, I that could change in a heartbeat. And this was one of those issues where we have to be clear about what we know and don't know. And I say with great humility, we don't know what the next shoe might be to drop with this issue, but none of the evidence to date supports the fact that this is going to be a major human pathogen issue. This virus has been around with us since 1997. It has not yet become that virus that is easily and readily transmitted by humans to humans. Will that change? We don't know. It would have to undergo major changes.


Michael Osterholm: In fact, uh, genetically for that to happen. One area that we all are very concerned about is a lack of testing and follow-up in swine that may be co-located in farms or near farms with dairy cattle could become infected. And as I've shared before, swine have receptor sites in their respiratory tract for both the bird viruses and the human viruses. And [00:15:00] one of the concerns we have is a concept called reassortment. It's where a pig is co-infected with two viruses, a human and an animal virus. They mix it up, they reassort their genetic material, and voila, you get a new virus that can cause a pandemic. That's exactly what happened in 2009 with H1n1 in Mexico, where in swine operations reassortment occurred, causing the new pandemic. So at this point, stay tuned. Number one pasteurized milk and milk products such as cheeses are safe relative to this virus. No reason in the world you should not continue to consume those. Number two, raw milk is an unsafe product, whether it's from a standpoint of influenza or any other infectious agent I've spent my career working on. Unfortunately, some very tragic outbreaks of infectious diseases E coli, O157, H7, salmonella, etc., are all associated with raw milk consumption. The most notable outbreak that I worked on was started in 1983 into 1984, in Brainerd, Minnesota, for a disease that ultimately became known as Brainerd diarrhea, where 122 people became infected from drinking raw milk and they were sick on average more than one year, with oftentimes having up to 20 stools a day.


Michael Osterholm: At this time, we still have not determined what the causative agent is, even though we know it's an infectious disease. And there now have been at least ten outbreaks of Brainerd diarrhea associated with raw milk consumption. So it is not just for influenza, but also for all these other infectious agents. I strongly, strongly urge you not to consume raw milk or for that matter, even cheeses made with raw milk. But in the meantime, we're going to be finding out a lot more about what's happening in the animal kingdom with this virus. Uh, it's going to be an important investigation in terms of trying to track the virus, to see are these changes occurring. But in the meantime, the message I want to leave you with is we are not in a major human public health crisis, but I reserve the right to change that opinion quickly if, in fact, we see genetic changes. So I. Hope this puts to rest for some of your anxieties about what's happening right now, but it sure should not lead to complacency. We have a lot of work we need to do to understand what's happening here. We are totally in uncharted territory in terms of what the flu virus is doing in the animal kingdom, and does that tell us that it may do something different in humans? We don't know. Stay tuned.


Chris Dall: Okay, so as you just noted, H5N1 does not at this point pose a widespread threat to the public. But in an opinion piece for The Washington Post last week, contributing columnist Leana Wen wrote that in the event that avian influenza does become the next pandemic, the US government is much better prepared than it was for COVID-19. Mike, do you agree?


Michael Osterholm: Chris, I unfortunately have to disagree with Leana Wen and what she wrote in her column. And it's not just about influenza, it's about any preparedness we have for the next pandemic virus is going to emerge. We all have to be very cautious about what I call happy talk, where we want to reassure people, because that's a lot easier to do than to have people not like you, because what you're sending them a message that they don't want to hear. But scientific fact and truth have to be what rule the day. In Leana's piece, she noted a number of things. For example, we now have much easier access to personal protective equipment such as masks, gowns, and goggles through commercial markets. And she went on to say, of course, we have the stockpile. But when you look at the PPE requirements of a pandemic that may last two, 3, or 4 years as influenza pandemics in the past have, and what our most recent COVID pandemic did, we would quickly outstrip the protective equipment availability and again, have real challenges fulfilling that. So yeah, it feels good to say the system looks pretty good right now. It's really good to say we have some stockpile, but show us the numbers if we in fact have this level of need for health care facilities, for the general public, for essential workers, what would actually be the runway of availability? And I can tell you it wouldn't be there.


Michael Osterholm: Another thing that Leana noted that is reassuring, at least to the public, is that we now have antivirals for influenza that appear to work at least against this virus, the one that's circulating in animals. Mind you, that won't be the one that, in fact, will ultimately infect humans because this virus has to change to do that. But what was missed in all of this is, again, what is the actual production capacity and the stockpile for these drugs? But more specifically, not one mention was made of testing. Well, we're not going to hand out antivirals for influenza willy-nilly just because somebody says they've been infected or sick. It's going to, again, much like COVID, require some evidence of positivity. And we have no good testing infrastructure in this country today. If nothing else that we learned in the COVID pandemic is throwing all kinds of money at new startup companies to do testing, ended up becoming a testing disaster. So I look at the testing as the major challenge for getting antivirals to the public. And again, that was not noted at all. And then we get into the vaccine area. And this is something our group has been very actively involved with for more than 20 years.


Michael Osterholm: We wrote the very famous report back in 2012 called the CIDRAP Comprehensive Influenza Vaccine Initiative Report, in which we laid out the relative lack of ability to manufacture vaccines in any timely manner. And in fact, we showed clearly in 2009, for example, that the first vaccines did not arrive until almost eight months after the pandemic began, long after the two big peaks of cases had occurred. Well, without getting into great detail, the same is true here. We would need to have literally likely two doses for every human on the face of the Earth, i.e. 16 billion doses of vaccine. If we were to try to cover the needs of the world and we won't have that. And even the vaccines that we have stockpiled today in the 20 to 30 million range, we have no assurance whatsoever that these would be the vaccines that would be effective against a new emerging strain. Remember, I just have hit home several times in this podcast that the virus that would infect us, causing the next pandemic would have to be one that changes from what it is now because in fact, we're not seeing human cases associated with this virus in any meaningful way. So a change occurs. What would happen with the vaccine? Let me take you back to 2009.


Michael Osterholm: We had a seasonal H1n1 vaccine that was working, you know, relatively well. Along comes the new pandemic strain of H1n1, and there was no cross-protection from the seasonal flu vaccine, H1n1 to the new pandemic H1n1 strain. Now, if you can't get it to work under those conditions where it's really, you know, you already have a vaccine, it gives you a sense of just how potentially complicated it's going to be to find the vaccine strain that works best. And I believe it's very likely will not occur until such a pandemic virus emerges. In other words, you can't stockpile vaccines in advance and hope that in fact, these will be the ones that the new virus that's causing the pandemic will actually, uh, be well matched to. So I think we surely want to celebrate the advances we've made. But we still see very limited increases in production of flu vaccines to what we had, uh, you know, 8 to 10 years ago. We do have new mRNA technology that could potentially be used, but without an adjuvant, that chemical that's added to the vaccine to give you a boosted immune response, uh, which we do not have with mRNA. We don't know how well they'll work against the virus. And one of the other additional issues we don't really understand is what is the dose going to be. Right now, our seasonal flu vaccine has 15 micrograms of antigen for each of the different antigens in the vaccine.


Michael Osterholm: Research recently has shown, however, that even with the H5 strains of virus we see now, we needed up to 90 micrograms of antigen per dose and then two times two. So instead of a 15 microgram one time, we're now talking about 180 micrograms over two different doses. Think how much that cuts into our capacity to actually provide vaccines for the world. So at this point, I just come back to the fact that, you know, one, what would our preparedness be for a future pandemic? And as I've said time and time again, I think it's limited. As I've shared with you, I have a book coming out at the beginning of next year on this very issue, which I try to go through very carefully and detail what it is that we have learned from the previous pandemic and what haven't we learned, and what that means in terms of our preparedness for the future. So in this case, I do not support the general conclusions of the Washington Post piece and think this is where both humility but honesty have to be the two common values that lead us forward in our preparedness for the next pandemic.


Chris Dall: So let's turn now to COVID-19. Mike, what are you seeing in the latest US and international data? And I should note here too, that April 30th was the last day that US hospitals were required to [00:25:00] report their COVID-19 data to the CDC. So is that going to make this part of the podcast even more difficult going forward?


Michael Osterholm: Well in terms of the overall activity with COVID. Chris, these are some of the best days that we've experienced since the pandemic began. I mentioned the April Situation report published by the W.H.O. in our last episode. Well, with the monthly updates, we're still a couple of weeks out from another report. So on an international basis, it's challenging to know exactly what's happening in a comprehensive manner. We just don't have the data otherwise. However, some good news is that here in the US, the declines we've been seeing appear to have only continued. Wastewater data is still trending down nationally and now sits at levels close to where we were last summer when we hit record-low numbers of cases. And on that note, it makes me very, very happy to announce that COVID-19 hospitalizations in the US have actually reached a new all-time low, dipping below 5200 as of April 20th. This speeds the previous mark of 5400 cases set in July of last year. And to get to this point, remember that it took 15 straight weeks of declines, moving us from a peak of 30,000 in early January to where we are at now with only 5200 hospitalizations. So hopefully we'll only see this continue. But as you noted, due to a change in the requirements for the Center for Medicare and Medicaid Services, for hospitals to report their COVID hospitalizations, and that has changed as of May 1st, the true national picture will almost surely become increasingly obscured as we move forward.


Michael Osterholm: So I wouldn't be surprised if we see major drops in the number of hospitalizations reported, of which will be an artifact it won't be capturing some of those individuals who are hospitalized. But again, we are really seeing this big decrease otherwise. Finally, with COVID deaths, weekly totals in the US have also continued to improve as of late March, which is the latest complete data we have available. Weekly deaths stood at 648, although that's not quite yet at an all-time low, which still stands at 491. In one week this past July. We're up to now at least 11 consecutive weeks of declines that began when weekly deaths were almost to 2600. And now, with hospitalizations continuing to drop, I wouldn't be surprised if we also see COVID deaths in the US soon reached new record lows. So here we are today talking about 648 deaths, again, reminding everyone that these are someone's loved ones. This is not just a number, but if you compare that to where we were the week of January 9th, 2021, in this pandemic, when 25,974 people died that week. It's remarkable drop. Today we stand at 2.5% of the deaths that we saw at the peak of the pandemic of very, very notable and very welcome drop. So overall, I think this is great news. Uh, what will happen in the future? I'm not sure if we're still tracking the evolutionary path of this virus, which always seems to twist and turn.


Michael Osterholm: And now we've seen a new variant, Cp2, overtake J1 as the most prevalent variant in the US. As of late April, Cp2 accounted for 25% of all US cases, compared to J1 at 22%. So after months of G1 dominating the variant race, there's a new leader in Cp2. Although it is worth noting that Cp2 is still a descendant of the J1 variant, with a couple of mutations in the spike protein appearing to give it some advantage. So what does this mean? Well, I don't really know. We could continue to see declines. We might see a case of plateau, and we could actually see an increase again as waning immunity and new variants come together. We just don't know I know we're not done with COVID, but I am hopeful that we are done with those horrible, horrible days that we experienced over much of the last four years. So trying to provide you with honest and realistic information for the future is kind of like trying to solve the world's longest calculus equation with a thousand different variables you got to try and account for. Surely the viral variant can be a very significant variable in this equation, but then I'm afraid there still are 999 other variables that interacts with. So we will have to wait and see. But again, I'm excited by the fact we're continuing to see these declines, at least for the time being.


Chris Dall: Turning now to long COVID. As we noted last episode, we're going to provide regular updates on long COVID news and research. Mike, what do we have this week?


Michael Osterholm: I'd like to discuss two studies that came out this past week that I think really provide us, again, [00:30:00] with some new and encouraging information. The first study assessed taste and smell in 340 participants with a history of COVID infection and 434 participants without a history of COVID infection. The researchers assessed taste using a 53-item test and smell using a 40-item test, both of which have been previously validated for clinical use. They found that there was not a significant difference in the ability to taste among the two groups, but the participants with a history of COVID had a 1.6 times higher likelihood of experiencing some degree of smell loss compared to those without a history of COVID. That said, the difference on average was very small, with those without a history of COVID having an average score of 35.9 out of 40 and those with a history of COVID having an average score of 34.4. As you can do the math, that's only about 4.2% lower. Additionally, the researchers recruited study participants through social media, so it should be noted that this may not be a random sample, which means the results are not necessarily generalizable to the entire population. But the results here do suggest that, in fact, that those with COVID over time will not suffer from these residual lack of taste and smell issues. A second study that I want to briefly mention was recently published in The Lancet, which looked at tissue samples from 225 COVID patients that were hospitalized for reasons not related to COVID, either one, 2, or 4 months after their acute infection.


Michael Osterholm: Again, remember, these were people hospitalized not for COVID, but after they'd had a COVID illness. The researchers found that 30% of the patients still had viral RNA in their tissues at one month following their acute infection, 27% still had viral RNA in their tissues at two months, and 11% still had viral RNA in their tissue at four months. Those who had viral RNA in the tissues had a 5.2 times the higher likelihood of having long COVID symptoms, compared to participants who did not have viral RNA in their tissues. Additionally, the researchers found that having more viral RNA in their tissue was associated with a higher odds of having long COVID. This finding could very well help us understand the pathology of long COVID in a way that says, how do we accelerate the loss of this viral RNA in body tissue? What can we do about that? And it surely gives us another avenue for therapies that could, in fact, have a big impact on long COVID. As was always the case with long COVID research, none of these studies give us all the answers as to what exactly long COVID is, why it is happening, and how we can treat it. But they do offer some good insights on the prevalence of certain symptoms and evidence for a potential mechanism of disease. As always, to all of our listeners who are directly or indirectly impacted by long COVID, we support you. We continue advocating for you, and I hope we're able to share increasingly hopeful news that you see in the months ahead.


Chris Dall: It's time now for our ID query. We're going to turn back to H5N1 because we've gotten a lot of questions from our listeners about the safety of the milk supply. So as you noted earlier, Mike, raw milk and raw milk products are a different conversation. But is the supply of pasteurized milk in the United States safe to drink?


Michael Osterholm: Well, let me just start out this section by saying this is a topic area that has long been part of my career, uh, challenges. Unfortunately, in my career, I've led a number of investigations addressing outbreaks of infectious diseases associated with raw milk consumption. In addition, the single largest foodborne outbreak ever recorded in our country's history, a salmonella outbreak associated with Schwan's ice cream back in the 1990s was a situation where pasteurization effectively killed the pathogens in the ice milk mix that was going to be used for ice cream. But then it got mixed in tanker trucks that were not sufficiently cleaned after hauling raw egg and recontaminated the product, resulting in well over 250,000 cases of salmonella infection. Needless to say, pasteurization is something that I've looked at very carefully, so I do understand why our listeners and everyone is concerned about this critical issue. Milk is on the table of millions of American households. Pasteurization, as our listeners may know, is the process of heating beverages like milk at a certain temperature for a certain time to kill the pathogens. It was first patented by Louis Pasteur to safeguard beer from spoiling. The practice was then adopted in the early 1900s by the dairy industry, when raw milk consumption was linked to tuberculosis outbreaks, and had been crucial in preventing outbreaks since.


Michael Osterholm: More on this history later in our public health history segment, pasteurization can be effective in activating H5N1 virus, along with all other nasty [00:35:00] viruses and bacteria that can flourish in raw milk without proper treatment. The level of heat kills the virus but leaves fragments and debris in the milk, which is why we're seeing reports of detections and products from H5N1-infected farms. Frankly, the same thing would be true whether it be salmonella or E coli, or listeria. They're dead, but they're still there. If we tested for them as antigens, meaning not do they grow? But can we detect their presence? They'd be there. The public and scientific community needs answers and more transparency from the USDA and FDA on this issue. There is still much more to learn here in order to lead with data-driven policy. But let me be clear, I'm only stating that to reinforce the safety of pasteurization, we can't just tell you as a public, don't worry, everything's okay. I would love it right now if we had the data looking at pasteurization relative to contaminated milk with H5N1. And what does that mean? The very first data that we're seeing right now is very, very encouraging. And I just want to come back to that and say that there have been limited studies looking at milk that was PCR positive and then cultured for virus and no live virus was found.


Michael Osterholm: So I feel confident about that. As I noted in the previous question and answer, again, raw milk products should never be consumed. As I just pointed out, I've worked up far too many outbreaks of Campylobacter, E coli O157H7, bovine tuberculosis, Listeria, and Salmonella. All of these have been challenges. And of course, the ones for which I never forget is the 1983-84 outbreak of Brainerd diarrhea. Where to watch 122 people ill for months and months and months with really devastating diarrheal illness is a remarkable and is a challenge. So let me leave you with this message. Do not interrupt, stop any of your current purchasing of milk and serving it to your family unless it's raw. And then stop, please. But not just for H5N1, because we don't even know for a fact that you could transmit H5N1 infection to a human by actual oral consumption of milk. We don't know that, but we do know you can transmit a lot of other deadly infectious agents to your loved ones. So from that perspective, milk is fine. If it's pasteurized, milk is not fine if it's not.


Chris Dall: So this discussion of pasteurization leads us to a very timely this week in public health history. I think our listeners can probably guess what we're going to talk about. But Mike, who and what are we commemorating on this episode?


Michael Osterholm: Well, let me start out by saying that this week in public health history does, in fact, link up quite remarkably well with the current events of the day. And I'm going to highlight, uh, French scientist Louis Pasteur in that regard. But I want to start out, first of all, before I address specifically his work in pasteurization, i.e. the name pasteurization after Louis Pasteur. But the fact that one of the most important messages I've ever received in my career was from a mentor, Doctor Alex Langmuir, who is the person who started the Epidemic Intelligence Service program at the Centers for Disease Control and Prevention back in the days when it was called the Communicable Disease Center. Um, and Alex was without a doubt one of the finest investigative epidemiologists ever in the business, ever. And Alex lived by a quote that came from Louis Pasteur. And that quote was chance favors the prepared mind. As a professor today. If I do nothing for my graduate students, it's hopefully not to have them memorize facts. It's not to have them, you know, be able to recite some public health creed. It's basically ensure that they have a prepared mind looking at the wide, broad brush of life. And you can't be a public health practitioner limited in very narrow silos of information. It's got to be prepared for whatever's going to happen. And that, in fact, is when chance favors the prepared mind. So let me now talk about this week in public health history. As I noted, this is extremely timely considering our conversation about dairy cows in the safety of raw milk.


Michael Osterholm: On April 20th, 1862, French scientist Louis Pasteur conducted the first successful test of what is now known as pasteurization, a process that could heat food products like milk to kill harmful microorganisms and not heat them sufficiently to destroy the taste or the texture. But that's where the time comes in. It's a time and temperature combination. Centuries before Pasteur's birth and before a widespread understanding [00:40:00] of germ theory and the role of microorganisms, people sought out methods to preserve food products. There's evidence that communities in both China and Japan were heating wine to reduce spoilage as early as the 12th century, but again heating it not to destroy its taste and texture enough heat to give it that same taste and texture. But killing those organisms that could, in fact, cause illness. Coming into the 1700s, Italian priests developed methods to boil meat, broth and seal in an airtight container to improve shelf life. French chefs and scientists furthered these methods and other food products, with support from the French military, to find improved methods of preservation. Slowly increasing urbanization meant that milk from farms had to travel longer distances and potentially sit on shelves longer, resulting in even more prolific pathogen growth in milk. In the 19th century, Louis Pasteur began his scientific work across multiple disciplines, including physics, chemistry, and biology. Bacterial pathogens were both a personal and professional issue for Pasteur. He witnessed the death of three of his five children from typhoid.


Michael Osterholm: Though his experimentation with fermentation and bacteriology, he began to understand how time and temperature could inactivate or kill harmful microorganisms. He eventually patented a method that took into account the food or beverages pH, and used mild heat for a calculated amount of time to reduce any chances in the flavor or quality of the product, while still killing any harmful organism. Today, there are multiple methods we use across food products that were built upon Pasteur's patented method for milk. Specifically, many of us in the United States are now most accustomed to a high-temperature, short-time pasteurization method that results in a refrigerated product lasting 2 or 3 weeks. Again, pasteurization doesn't kill all the spoilage bacteria. That's what causes milk to go sour, but it does kill those organisms likely to hurt us. Across the world, many people drink ultra-high temperatures or use milk stored in aseptic packaging, which has up to a nine-month shelf life outside of a refrigerator. There's also an increased trend in still pasteurizing milk, but not homogenizing the fat globules leaving a cream top. This may be a more reasonable option for those who choose to drink raw milk based solely on its consistency, while still maintaining a much higher safety profile. I'll reiterate one more time how grateful I am for the discoveries we've made and continue to improve upon regarding food safety and hygiene. Let's not be foolish and put ourselves back in the danger of pathogens we know how to prevent.


Chris Dall: Now it's time for another segment marking the four-year anniversary of the podcast. Today, you're going to hear from two more members of the podcast team who dive into the data to help us and your listeners understand what's going on with COVID and other infectious diseases like H5N1. Mike, take it away.


Michael Osterholm: Well. As the podcast audience knows, we have spent the past several episodes sharing with you the podcast team here at CIDRAP, a wonderful group of individuals who make these podcasts not only possible, but really are responsible for the quality of the information that I have the opportunity to share. And today, we're going to complete the introductions with our last two members of the podcast team, two very important members in terms of the research, and really laying out the topics as we provide them to you. First is Angela Ulrich, who has been with us for several years now, who is very involved in working on the roadmap work that we do with vaccines. And Meredith Arpey, a graduate student, happy to report she's at my PhD student and who also has been actively involved in this work area. So I want to just welcome both of you, Angie and Meredith. And to say on behalf of all the team, thank you so much for what you do, but to have the podcast family better understand who you are. I think I'll start with you, Angie, and just if you can tell us a little bit about your background, how you got to CIDRAP, and how you got involved with the podcast.


Angela Ulrich: Sure. So I am an infectious disease epidemiologist by training. Uh, before I came to CIDRAP, I was doing my postdoctoral fellowship in epidemiology at the University of Minnesota. And then prior to that, I earned my PhD and my master's in public health, also in epidemiology from the University of Washington. I started at CIDRAP in 2020. I first met Mike taking his emerging infectious disease course in 2020 while the COVID pandemic started. And so I got to hear in real time, uh, Mike's thoughts and ideas about what was happening and what was unfolding. And it was shortly after that that I, that I joined the CIDRAP team. And shortly after joining the CIDRAP team, I became [00:45:00] involved in in the podcast, as that was starting to unfold, and learned how to do, uh, research on emerging infectious diseases very rapidly as we were trying to put together information and inform you, our podcast family about what was going on with COVID at CIDRAP. Much of my work right now focuses on research that's related to pathogens with pandemic or epidemic potential. So Mike mentioned, uh, the roadmaps I work on those for influenza, coronavirus, and other pathogens such as Zika, particularly related to the research and the policy surrounding vaccines. So I'm again involved in two different initiatives that aim to accelerate research and development of vaccines one for an improved influenza vaccine and the other for an improved coronavirus vaccine.


Michael Osterholm: Thank you, Angie. And I must note that for some of the listeners on this podcast, they recognize this. But CIDRAP has had a very special relationship with Luther College in Decorah, Iowa, my alma mater, in which we've had a number of students come through, uh, have attended Luther and now are in graduate school here. And I'm very proud to say that Meredith is one of those. So, Meredith, uh, maybe you could, uh, answer those same questions that Angie just did.


Meredith Arpey: My interest in public health really started at Luther throughout my liberal arts education, and I took courses in a plethora of different fields, but, uh, really became interested in the one health approach and ended up doing my capstone in environmental health. And it focused on the effects of climate change on the spread of malaria, which really kind of started my interest in public health. But I ended up pursuing my MPH at the University of Minnesota, which landed me in the same course, the emerging infectious disease course, where my Luther connection played out pretty well, and I was able to get my way into the CIDRAP team. So Corey reached out to me, and that's how I got started. Um, I work on several different influenza-related projects at CIDRAP. My primary project, which is how I got started, is the Universal Influenza Vaccine Technology Landscape, which is a database of flu vaccines that are designed to provide broader and more durable protection against circulating and pandemic influenza viruses. Um, and so I've been working on that since 2019. And again, my Luther connection with Corey played out again when I reached out and offered to help with the podcast in 2021. So I actually looked back. And today marks well this week. Marks my third anniversary. I started in April of 2021 on episode 53, which was two doses of vaccine and one dose of humility.


Michael Osterholm: Well, thank you very much. And, uh, for those of you may recall, Corey Anderson, uh, was interviewed in a previous episode, and that's who, uh, Meredith was referring to. And so I want to thank again, both of you for your major contributions. So, Angie, let me, uh, come back to you and, uh, just have you reflect on what are some of the lessons you've learned about public health messaging in participating in this podcast, and how our own research efforts had to account for that? And you are a very key piece to that.


Angela Ulrich: I think one of the more important things that I've learned through working on the podcast, but also that we've seen happen throughout COVID, is the importance of being able to communicate the science in a way that's accessible to everyone. We can have the best science in the world, but if people don't understand it and if they don't trust it, it doesn't matter. So I think specifically about vaccines, which is an area that I am interested and do a lot of work in. We know a lot about vaccines. Uh, we know especially, um, the vaccines that we use for coronavirus or COVID-19 are safe. They're effective to a certain extent. And yet we have a number of people who have major barriers to accepting those vaccines. And so I think what I've learned is how important it is to think about those things from the very beginning of vaccine development or the very beginning of an intervention you're thinking about and think about how do you communicate that with the public. Some of the more complicated issues surrounding how do we measure vaccine effectiveness? How do we measure efficacy? How do we design an appropriate clinical trial or a randomized trial in the population? Um, and being able to distill that down to the most important factors so that we can communicate that these [00:50:00] vaccines are safe, they're effective, and, uh, give people the best options and the information they need to make decisions for themselves and for their families.


Michael Osterholm: Thanks, Angie. And how about for you, Meredith?


Meredith Arpey: Yeah. So I think one thing that stuck out to me while working on the podcast, um, is that you really need to meet people where they are. You're not going to change someone's mind who's stuck on that. The vaccine is it doesn't work, and it's a way to implant a chip in your arm. You're not going to get those people to be convinced that they should be vaccinated. But you can present the science, as Angie kind of mentioned, and give them the information that you have to be able to help them maybe make a decision for themselves. But you can't force people to do anything. A mandate isn't necessarily going to get you the result you want. And so I think you have to be careful with your messaging and meet people where they are.


Michael Osterholm: Again for all the members of the podcast team. Thank you so very, very much. And just as your colleagues have had the opportunity and their previous interviews to ask me a question, I'm going to turn the tables on me at some obvious risk and ask you to ask me a question. So, Angie, you're up first. Uh, what question would you like to ask me?


Angela Ulrich: So, Mike, last episode you answered a question about your public health mentors, but you yourself has served as a mentor to countless public health professionals throughout your career. So I'm curious, what advice do you have for people who are just starting their public health journey, either as a student or someone who's more in a more junior stage of their career?


Michael Osterholm: First of all, let me just say that it is such a privilege to be part of a public health team. You know, my almost 50 years now in the business, and I've never regretted a day of it. Uh, I've worked with the good people, the really good people. Uh, and so I would say the most important thing is to know that you're entering into a career where it is about the common good, it's about helping. It's about the positive aspects of life. And I guess part of what we've tried to do with this podcast is share that very essence of what it means to be part of the podcast family, but what it also means to be part of public health. So I would just say, uh, we need you. Public health will forever be a field where, uh, we'll never have enough qualified and, uh, really committed individuals to carry out public health practice. So, uh, I just encourage people to get involved, to know it'll make a difference. And there have been many, many nights when I've laid my head on that pillow where I don't know for sure if anything I did today made a difference to make people's lives better. But I know for certain that I spent the day with the good people, the people who care, the people who are trying to make a difference, the people who are trying to reduce suffering and in improving the quality of life. That's an absolutely priceless gift that, uh, everyone who comes into public health has that opportunity to know. How about you, Meredith?


Meredith Arpey: So, Mike, you've accomplished a lot throughout your career and have connections across the world which have provided some pretty cool opportunities. For example, a starring role in Wicked. So my question is, has there been a moment of imposter syndrome where you've taken a step back and thought to yourself, wow, how did I get myself into this situation?


Michael Osterholm: Well, I would actually have to say, Meredith, I have that feeling probably more than I don't have it. And I still do after 50 years. Uh, you know, there are times that I, I feel like I need to pinch myself to understand that I'm being able to be part of, of something very special. And I would have to say that public health is about relationships. You know, over the 50 years I've had the opportunity to meet many, many different people. Uh, so many of them were such dedicated and thoughtful people who cared for which the relationship just goes on and on and on. And, you know, there's nothing more valuable than being able to get on the phone or get on your computer and contact someone who may be halfway around the world and to work with them, because it's not a first call. It's been many calls. It's been many conversations before that. So I think that's one of the real blessings in public health is that you accumulate these very important relationships over time. And it is really possible to shortcut a lot of challenges if you can get the right team of people together who all have the different tools, uh, have different abilities to, to contribute, who have access to different, uh, points of, of activity. And I think that's, that's the key. I [00:55:00] you can never have too many colleagues in public health and more importantly, special colleagues. So thank you both for those really good questions. Uh, and again, to the listeners, you've now had a chance to meet all of the podcast team. And as I've said so many, many times, I owe that team an amazing amount of gratitude for what they've done to allow me to do what I do, to speak with you every two weeks. So thank you very much.


Chris Dall: Stay tuned for more on our next episode, when you'll hear from CIDRAP's Deputy Director Eve Lackritz. And just a note to our listeners if you would like daily updates on COVID, H5N1, and other news from the world of infectious disease, please sign up for CIDRAP's daily news Headlines newsletter. No fees, no paywalls, just a daily email in your inbox. You can find a link to sign up for that newsletter in the show. Notes. Mike, what are your take-home messages for today?


Michael Osterholm: First. Chris, I have to celebrate the progress we've made in COVID. And while any time we have people seriously ill or dying from it is a concern, it's a real concern. But again, as I pointed out, we are at 2.5% of the deaths we were back in January of 2021. It's a remarkable observation to be able to make. So we have to continue to monitor COVID. We have to continue to make sure we stay on top of it. But we also need to acknowledge we've come a long ways. Second, H5N1 is a very important public health issue, but I would lead off by saying I still do not see it as a major imminent public health threat for humans. That could change in a heartbeat. And so I want to reserve that possibility because that's what flu viruses do. But after all the time since 1996 to now, we have yet to see real evidence that this is going to become a future human pandemic virus. And finally, last but not least, raw milk. Please, for the sake of your children, for your friends, your neighbors, all those who might consume raw milk, please don't. We have so many outbreaks of infectious disease that occur associated with raw milk, and as much as the community that advocates its use and makes basically claims about how much healthier these are simply not true. They are not based on fact. And having worked up far too many outbreaks, including the death of young children who consume contaminated raw milk. I never forget what that all means.


Chris Dall: And Mike, what is our closing song for today?


Michael Osterholm: Well, Chris, another oldie but goodie. It's not that old, but it's one that has meant a great deal to me, and it's in some ways the basis of how I try to approach these podcasts. And it seemed like it was a good reminder, uh, what's important here and what I'm trying to accomplish with you and the rest of the podcast team. It's one that, uh, we've actually used five times already. Some of you probably have guessed it already. What it is. It's Letter to You, which, as you know, is the 2020 single hit by Bruce Springsteen and the E Street Band. This was a song written by Bruce and reflected the message to his fans that he was trying, to his very best to write what he knew and what he felt in a letter to them. And to me, these podcasts really have been a way for me to try to share with you what it is that I think or feel or experience or don't know or worry about. And so here it is, a Letter to You by Bruce Springsteen. Neath a crowd of mongrel trees I pulled the bothersome thread, got down on my knees, grabbed my pen, and bowed my head. Tried to summon all that my heart finds true and send it in my letter to you. Things I found out through hard times and good I wrote them all in ink and blood. Dug deep in my soul and signed my name true. And sent it in my letter to you. In my letter to you, I took all my fears and doubts. In my letter to you.


Michael Osterholm: All the hard things I found out in my letter to you. All that I found true. And I send it in my letter to you. I took all the sunshine and rain. All my happiness and all my pain. The dark evening stars and the morning sky are blue. And I sent it in my letter to you. I sent it in my letter to you and my letter to you. I took all my fears and doubts in my letter to you. All the hard things I found out in my letter to you. All that I found true. And I sent it in my letter to you. I sent it in my letter to you, Bruce Springsteen, and the E Street Band. Thank you very much for joining us for another episode. I hope that we're able to provide you with the kind of information you're looking for today. And, uh, it's a crazy [01:00:00] infectious disease world out there on top of a crazy world in general. Uh, but I hope we all can come together on this podcast and find the information and find the place in the space that we need to be. So everyone have a good two weeks. Enjoy spring that sunlight's getting better if you're in the northern hemisphere. And thank you so much for being with us. Um, I can't tell you how much it means to the podcast team and myself. And um, again, as I say so often, but say so sincerely be kind right now. If the world ever needed it, it's the time for people to be kind. Thank you.


Chris Dall: Thanks for listening to the latest episode of the Osterholm update. If you enjoyed the podcast, please subscribe, rate, and review wherever you get your podcasts, and be sure to keep up with the latest infectious disease news by visiting our website This podcast is supported in part by you, our listeners. If you would like to donate, please go to The Osterholm Update is produced by Sydney Redepenning, Elise Holmes, Cory Anderson, Angela Ulrich, Meredith Arpey, Clare Stoddard, and Leah Moat.