At a briefing on global health issues today, the head of the World Health Organization (WHO) said there are concerning trends ahead of the Northern Hemisphere winter, including rising deaths in parts of the Middle East and Asia and increased hospitalizations in multiple regions.

WHO Director-General Tedros Adhanom Ghebreyesus, PhD, included the caveat that data are limited, with few countries reporting information. Regarding variants, he said there is currently no dominant one, though EG.5 is on the rise. He said the heavily mutated BA.2.86 variant has been detected in small numbers in only 11 countries, though the WHO continues to monitor developments, especially regarding transmissibility and potential impact.

Over the past day, variant trackers have noted BA.2.86 sequence uploads from more countries, including Australia, and more from countries that already reported sequences, including the United States, involving a sample from Colorado. Delaware yesterday reported its first BA.2.86 case, which involves a Pennsylvania resident who was seen at a Delaware hospital.

By the latest count, at least 84 samples have been uploaded to sequencing databases. Also, scientists have identified the first BA.2.86 sublineage, designated as BA.2.86.1, which has two additional mutations and a synonymous nucleotide mutation.

Tedros added that one of the WHO's biggest worries is the low number of at-risk people who have recently received a dose of COVID-19 vaccine. "Our message is not to wait to get an additional dose if it is recommended for you," he said.

Moderna: Updated vaccine shows strong response against BA.2.86

In related developments, Moderna today announced that a clinical trial with its research assay suggests the updated vaccine, which is under Food and Drug Administration (FDA) review, generates an 8.7-fold increase in neutralizing antibodies in people against BA.2.86.

In a statement, the company's president, Stephen Hoge, MD, said that, taken together with recent findings suggesting a similar response to newer variants EG.5 and FL.1.5.1, the data confirm that the vaccine will continue to be an important tool for protection heading into the fall vaccination season.

A 2023 survey of nearly 2,200 adults in Arizona who had received at least one COVID-19 vaccine dose shows that the most common reason for not receiving a bivalent (two-strain) booster dose was a previous infection, followed by concerns about vaccine side effects, safety, and effectiveness.

University of Arizona researchers surveyed 2,196 recipients of one or more COVID-19 vaccine doses from February 13 to March 29, 2023. The research was published this week in Vaccine.

The authors noted that, as of May 2023, less than 20% of eligible US adults had received a bivalent booster dose, which offers protection against both the wild-type and Omicron SARS-CoV-2 strains for people aged 6 months and older.

Concerns about booster safety, efficacy

Of the 2,196 participants, 74.5% had received a bivalent dose. The 559 respondents who didn't get a booster cited previous COVID-19 infection (39.5%), worries about vaccine side effects (31.5%), thinking that the booster wouldn't provide more protection than previous doses (28.6%), and concerns about booster safety (23.4%) and efficacy (23.1%).

The US Centers of Disease Control and Prevention says of bivalent vaccines, "The current evidence does not support the existence of a safety issue" and says serious side effects are rare.

Effectiveness of vaccines and boosters wane over time, making the development of and adherence to updated vaccine boosters a key public health strategy in protection from the worst SARS-CoV-2–related outcomes.

Participants aged 60 and older were less likely than younger respondents to cite reasons related to a lack of knowledge (odds ratio [OR], 0.24) or logistical concerns (OR, 0.09) about the booster.

Hispanic respondents were more likely than their non-Hispanic peers to indicate concerns about logistics (OR, 2.15), and those with some college or technical education were significantly more likely than college graduates to say that the risks and benefits of the bivalent vaccine were less clear than the reasons for not getting boosted (OR, 2.41).

"Effectiveness of vaccines and boosters wane over time, making the development of and adherence to updated vaccine boosters a key public health strategy in protection from the worst SARS-CoV-2–related outcomes," the researchers wrote. "Implementation remains among the biggest current public health challenges as updated boosters continue to be developed and made available to the public."

A new study by researchers in China highlights the threat of multidrug-resistant (MDR) and methicillin-resistant Staphylococcus aureus (MRSA) in packaged food.

In the study, which was published last week in the journal Zoonoses, researchers with the China National Center for Food Safety Risk Assessment analyzed 276 ready-to-eat (RTE) food-associated S aureus isolates collected from supermarkets, convenience stores, fast food restaurants, and farm-product markets in 25 provinces across China in 2018. The investigators assessed antimicrobial susceptibility, virulence factors, and molecular characteristics.

In 2015, Chinese researchers reported that 4.3% of retail foods were contaminated with S aureus, which can cause staphylococcal food poisoning (SFP), and that a much higher percentage of contamination was found in RTE foods. But the prevalence and epidemic characteristics of MRSA in RTE foods had not been established.

MDR, MRSA quite common

Of the 276 isolates analyzed, 250 (90.6%) were resistant to at least one antimicrobial agent, and 73 (26.4%) were MDR (resistant to three or more antimicrobials). Among the MDR isolates, 30 MRSA isolates were identified, and nine toxin genes were detected, with 18 (60%) of the MRSA isolates harboring multiple toxin genes. Thirteen sequence types were identified. The most prevalent MRSA lineages were CC59-t437-SCCmecIV/V (23.3%), CC398-t011-SCCmecV (23.3%), and CC1-t114-SCCmecIV (16.7%).

The study also found that the genotype diversity of the MRSA isolates was related to antimicrobial resistance and virulence genes.

"These results suggest that monitoring the genotypes of MRSA in RTE foods would be instrumental in tracing the source of contamination and assessment of antimicrobial resistance and risk of SFP," they wrote. "Therefore, such work will be helpful in assisting the government, food industries, and other stakeholders to improve food safety measures and control the transmission route of this bacterium."

• In an outbreak that began in April, Bangladesh is now experiencing its worst dengue activity, the World Health Organization (WHO) director-general said today. Cases are starting to decline in Dhaka, but are increasing in other parts of the country. At a briefing on a host of global health issues, Tedros Adhanom Ghebreyesus, PhD, said the country has reported more than 135,000 cases, along with about 300 deaths.
• Nigeria is experiencing its second diphtheria wave of the year, with 9,000 suspected cases across 17 states, 307 of them fatal, Tedros said at today's briefing. He said the WHO is working with Nigeria's government to improve vaccination, surveillance, and risk communication. "This outbreak and others highlight the need to increase routine vaccination to stop these outbreaks before they start," he said.

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  Uruguay is the latest country in South America to detect H5 avian flu in a sea lion, according to a notification from the World Organization for Animal Health. The juvenile animal was reported with nervous system symptoms on September 2 at a beach near Montevideo, the country's capital. Animal health officials obtained samples, which were positive for H5. The seal died where it was found, and responders conducted a sanitary burial and disinfected the area.