Quick takes: Imported oyster norovirus alert, poultry avian flu vaccine deliberations, Listeria and leafy greens

News brief
  • The US Food and Drug Administration yesterday warned consumers and retailers in Hawaii, Georgia, and Minnesota about certain frozen raw oysters imported from South Korea that may be contaminated with norovirus. Hawaiian health officials reported five illnesses in restaurant customers who ate the oysters, and norovirus GII has been detected in two product samples. Minnesota also reported five illnesses, likewise involving people who ate oysters at restaurants. The affected products were also distributed in Georgia.
  • The World Organization for Animal Health (WOAH) recently published a report that encapsulates a discussion on evolving avian flu control strategies, which included poultry vaccination as a complementary tool, and on challenges in implementing immunization. The discussions occurred during an animal health forum that was held during WOAH's annual general session in late May. Officials said successful immunization campaigns would hinge on authorized vaccines that closely match circulating strains alongside robust surveillance strategies. They adopted a resolution to shape future avian flu control strategies.
  • The US Centers for Disease Control and Prevention (CDC) said yesterday a Listeria monocytogenes outbreak linked to leafy greens appears to be over, with 19 infections reported in 16 states. Five more illnesses and six more affected states were reported since the CDC's last update on Apr 21. Eighteen people were hospitalized, but no deaths were reported. The CDC first announced the outbreak on Feb 15. Though investigations suggested that leafy greens were the source of the outbreak, CDC scientists didn't have enough data to identify a specific leafy greens source or grower.

Arizona announces recall of marijuana products because of Aspergillus, Salmonella

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Marijuana plant up close
Cannabis Urlaub / Flickr cc

Several Arizona marijuana establishments have voluntarily recalled certain products over potential contamination with Aspergillus and Salmonella. Arizona is one of 23 states that has legalized marijuana for recreational use.

The Arizona Department of Health Services (ADHS) said no illnesses have been reported and that its warning comes after its lab auditors found false-negatives for contaminants that were reported from a licensed marijuana laboratory. The four recalled products are all from the same cultivator, the Cannabist.

Three samples that were positive for Salmonella—Cap's Frozen Lemon, Twisted Lemonz, and Ghost Train Haze—involved live resin concentrate. The one that yielded Aspergillus was plant trim, a product called Cherry Punch.

The ADHS urged consumers who have products from the affected batch numbers to dispose of them. They said Aspergillus can trigger allergic reactions or infections, especially in people who have underlying health conditions. And Salmonella ingestion can result in diarrhea, fever, stomach cramps, and other symptoms.

Bioterrorism risk using natural pathogen sources low in the Netherlands, study suggests

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 Coxiella burnetii which causes Q fever
 Coxiella burnetii, bacteria that cause Q fever.
– NIAID / Flickr cc

A study published yesterday in Emerging Infectious Diseases finds low a incidence of pathogens with bioterrorism potential in the Netherlands, which the authors say would hamper efforts to isolate them from natural sources for intentional release.

A team led by Amsterdam University researchers used data on diseases published from 2009 to 2019 to calculate the average annual incidence of pathogens considered high risk by the European Medicines Agency or the US Centers for Disease Control and Prevention.

Pathogens in labs must be secured

The bacterium Coxiella burnetii (which causes Q fever) had the highest incidence because of a goat-related Q fever epidemic in the Netherlands from 2007 to 2019, peaking at 2,424 cases in 2009. The average incidence over the entire period was 171.2 cases per 10 million people, falling to 10.8 cases per 10 million (14 to 26 cases per year) from 2015 to 2019 after prevention efforts.

The incidence of the bacterium Brucella spp. (brucellosis) was, on average, 2.5 cases per 10 million people per year). Brucellosis was an imported disease only, with one to nine cases per year. Other bacteria with an incidence greater than 1 included Francisella tularensis (tularemia; 1.3 cases per 10 million per year) and Burkholderia pseudomallei (melioidosis; 1.1 cases).

Pathogens with an incidence less than 1 included hemorrhagic fever viruses (Ebola, yellow fever, Lassa fever; 0.3 cases per 10 million per year) and the bacteria Clostridium botulinum (botulism; 0.2 cases) and Bacillus anthracis (anthrax; 0.1 cases). There were no infections with variola major virus (smallpox) or the bacterium Yersinia pestis (plague).

"Most pathogens in the top risk categories only occur sporadically in the Netherlands, restricting access by ill-meaning persons," the authors wrote.

Most pathogens in the top risk categories only occur sporadically in the Netherlands, restricting access by ill-meaning persons.

"However, some of the pathogens are present in clinical microbiology laboratories," they added. "Therefore, those pathogens must have proper systems in place that cover the key areas of biosecurity to minimize the risk for misuse, such as a policy on personnel and information security, material accountability, and physical security, as well as biosecurity awareness." 

COVID-19 vaccines shown safe in 2 new studies

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COVID vaccine vial up close
International Monetary Fund / Flickr cc

Two new studies show COVID-19 vaccines are safe in older adults and when administered simultaneously with non-COVID vaccines. Both studies are published in Vaccine.

No increase in worrisome events

The first study, which looked at self-reported safety events for those 65 and older, included 3,360,981 people who received 6,388,542 primary mRNA series doses. A subsequent study on booster doses included 6,156,100 people who received one monovalent (single-strain) booster dose.

Adjusted incidence rate ratios (IRRs) were calculated for these serious heart and circulatory conditions, among other adverse events (AEs): acute myocardial infarction (AMI), myocarditis/pericarditis (Myo/Peri), immune thrombocytopenia (ITP), and disseminated intravascular coagulation (DIC).

For the Pfizer-BioNTech primary series and booster, the AMI IRR was 1.04 (95% confidence interval [CI] 0.91 to 1.18) and 1.06 (95% CI 1.003 to 1.12), respectively. For the Moderna vaccine, the rate ratios were 1.01 (95% CI 0.82 to 1.26) for the primary series and 1.05 (95% CI 0.998 to 1.11) for the booster.

The risk for AMI was reduced to nil after adjusting for other factors.

"Of six AEs evaluated in two independent population-based studies including the U.S. elderly population, no statistically significant increase in risk was identified for ITP, DIC, and Myo/Peri following COVID-19 mRNA vaccination for primary series and monovalent boosters," the authors concluded.

Co-administration not an issue

In the second study, safety data on simultaneous vaccination (SV) with primary-series mRNA COVID-19 vaccines was evaluated, based on reports in the Vaccine Safety Datalink. The authors used surveillance data from December 11, 2020, to May 21, 2022.

During the study period SV was uncommon, used by just 0.7% of 8,455,037 people for dose one and 0.3% of 7,787,013 people for dose two.

Only 56 safety outcomes were seen in the study, and the overall rate of outcomes among COVID-19 vaccinees who received SV was not statistically significantly different than among those who did not receive SV (6.5 vs. 6.8 per 10,000 patients).

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