The common cold may help protect against COVID-19, which may partially explain why children, who are especially vulnerable to most viral respiratory infections, generally have milder SARS-CoV-2 infections than adults, National Jewish Health–led researchers write today in The Journal of Infectious Diseases.

The investigators tested 10,493 repeat nasal swabs from 1,156 US children and adults in the Human Epidemiology and Response to SARS-CoV-2 (HEROS) cohort for 21 respiratory pathogens. They also performed RNA sequencing on 147 swabs from 144 participants taken before COVID-19 infection and 391 swabs from 165 participants before and during rhinovirus infection, which frequently causes the common cold.

"To determine the relationships between prior rhinovirus infection, subsequent SARS-CoV-2 risk, airway antiviral gene expression, and age, we leveraged data from the HEROS cohort, a prospective surveillance study of SARS-CoV-2 in households with children and teens, conducted from May 2020 to February 2021," the researchers wrote.

Rhinovirus also tied to lower SARS-CoV-2 viral load

Participants infected with rhinovirus in the previous 30 days were at a 48% lower risk for COVID-19 (adjusted hazard ratio, 0.52). Among COVID-infected participants, recent rhinovirus infection was tied to a 9.6-fold lower SARS-CoV-2 viral load, or amount of virus in the body, an indicator of infection severity. 

Rhinovirus infections, which trigger increased expression of antiviral airway genes, are linked to a lower risk of SARS-CoV-2 infection.

Higher pre-infection expression of 57 genes, including 24 antiviral defense genes, was linked to a lower SARS-CoV-2 viral load, with rhinovirus infection triggering expression of 22 of the antiviral genes. Children expressed higher levels of the antiviral gene signature and were at a 2.2-fold higher risk for rhinovirus infection than adults.

Sensitivity analyses suggested that, compared with more distant and asymptomatic rhinovirus infection, recent and symptomatic infections were associated with greater reductions in COVID-19 risk.

"Rhinovirus infections, which trigger increased expression of antiviral airway genes, are linked to a lower risk of SARS-CoV-2 infection," the study authors wrote. "Frequent rhinovirus infections may enhance this protective gene profile, partially explaining why children experience milder SARS-CoV-2 infections compared to adults."

A study in Israel confirms antibiotic use as a major risk factor for Clostridioides difficile infection (CDI) in hospital patients, particularly for those who don't carry the bacterium, researchers reported last week in JAMA Network Open.

For the study, which was conducted from June 2017 through June 2023, researchers analyzed data on patients admitted to a large tertiary medical center in Israel that routinely screens high-risk patients for C difficile carriage. While broad-spectrum antibiotic use is a known risk factor for CDI, the researchers wanted to evaluate the rate of hospital-onset CDI among asymptomatic C difficile carriers compared with noncarriers and assess the role of antibiotic exposure in shaping CDI risk in the two populations.

Antibiotic exposure linked to double the risk of CDI

Among 33,756 hospitalizations (median age, 78 years; 52.8% male), 1,624 (4.8%) had a positive screening result for C difficile. Overall, CDI occurred in 67 (4.1%) of 1,624 carriers and 47 (0.1%) of 32,132 noncarriers. 

In the entire cohort, exposure to any antibiotic was associated with double the risk for CDI (hazard ratio [HR], 1.98; 95% confidence interval [CI], 1.24 to 3.16), with each additional day of antibiotic exposure having an HR of 1.08 (95% CI, 1.03 to 1.13). Beta-lactam/beta-lactamase inhibitor combinations were associated with significantly increased risk, with piperacillin-tazobactam showing the most pronounced hazard for CDI (HR, 2.18; 95% CI, 1.41 to 3.36).

Although a positive C difficile screening result at admission was associated with a high risk of CDI (HR, 27.5; 95% CI, 18.7 to 40.3), antibiotic exposure among asymptomatic C difficile carriers was not significantly associated with a further increase in CDI risk (HR, 1.07; 95% CI, 0.73 to 1.58).

The study authors say the findings suggest that, while antibiotic stewardship may reduce CDI risk in noncarriers, additional strategies may be needed for asymptomatic carriers.

"Among carriers, preventive measures in addition to antibiotic stewardship should be evaluated in hospitalized patients and may include probiotics, monoclonal antibodies, or biotherapies," they wrote. "However, further research is necessary to evaluate the potential effectiveness of these interventions, their association with microbiome alterations, and potential changes in antimicrobial resistance patterns among patients and within the hospital environment."

The United Kingdom is experiencing an unusual rise in H5N1 avian flu outbreaks in commercial poultry, with 10 reported over the past 2 weeks. Also, Ireland on July 31 reported a similar outbreak in a small backyard flock.

The two latest UK outbreaks were confirmed at commercial farms in East Devon and West Devon. 

Last summer, Great Britain didn't report any poultry outbreaks from March to early April. Before the recent spike in detections, the country had lowered its threat level for farmers after going 5 weeks with no new detections. Mike Coston, a retired paramedic who has tracked avian flu developments over the past decades on Avian Flu Diary, an infectious disease news blog, wrote, “While this spate of summer HPAI [highly pathogenic avian influenza] outbreaks could prove to be little more than a transient event, it represents a change in the typical summer pattern—and is worth keeping our eye on.”

Sporadic H5 detections in other regions

Other countries have also announced recent H5 detections in poultry over the past few weeks, including Taiwan, Canada, and Cambodia, according to the latest weekly update from the Hong Kong Centre for Health Protection, which compiles recent notifications from the World Organization for Animal Health.

The last outbreak in US poultry was confirmed in early July and involved a game bird farm in Pennsylvania.

• As busy summer air travel continues, health officials in a handful of jurisdictions are investigating exposures following new detections in travelers, including San Diego County, which reported its first case of the year. The patient is an unimmunized teen resident who had recently traveled overseas and may have exposed people at two healthcare facilities, one in San Diego and the other in La Jolla. Los Angeles County said it is investigating a confirmed measles case in a traveler who was infectious while traveling through Los Angeles International Airport, arriving from China on August 2. Officials are working with the US Centers for Disease Control and Prevention to identify and notify passengers who were seated near the patient. And health officials near Toronto issued a warning about a confirmed measles case involving a patient who flew from Newark, New Jersey, to Toronto on an Air Canada flight on July 30, according to a local media report.
• Vinay Prasad, MD, MPH, the Trump administration's pick to lead the vaccines and biologicals division at the US Food and Drug Administration (FDA), has rejoined the agency after resigning in late July to avoid distracting from the agency’s work and to spend more time with his family. His exit 2 weeks ago came amid tensions following a gene therapy product and a campaign pushing for his ouster by Trump loyalist Laura Loomer.  Stat broke the news on August 9, confirming with a Health and Human Services spokesperson that Prasad was resuming the post upon FDA request. It's unclear if Prasad will also resume his previous dual role as the FDA's chief medical and scientific officer.
• In a new effort to battle the spread of New World screwworm to US livestock, the US Department of Agriculture is tapping horse-mounted patrol inspectors known for over a century as the "Tick Riders" to watch for New World screwworm (NWS) and to deploy preventive treatment to all stray cattle and horses apprehended at the US-Mexico border. In a press release, the US Department of Agriculture's (USDA's) Animal and Plant Health Inspection Service (APHIS) said the Cattle Fever Tick Eradication Program was first established in 1906 to battle cattle fever ticks, which can cause blood loss in cattle and spread diseases such as babesiosis and anaplasmosis. APHIS said the captured animals will be given NW screwworm preventives that are safe for animals and the environment and won't replace its other inspections for the disease. Northward spread of the fly Cochliomyia hominivora to as close as 370 miles from the US border prompted the USDA to reimpose a ban on livestock imports at the US-Mexico border.