Breakthrough Discovery: Departure of an Entire Influenza Virus Strain since 2020; WHO Recommends Exclusion from Future Vaccines
WHO excludes a family of flu viruses from future vaccines as they haven't been seen since the start of the Covid-19 pandemic Stay informed with CNN Health's weekly newsletter
When the World Health Organization provided its recommendations on Friday regarding the influenza viruses to be targeted in next year's vaccines, it excluded a group of viruses that has not been observed since the initial stages of the Covid-19 pandemic.
Sick woman wiping her nose with tissue paper
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A doctor can assist in differentiating between a cold, flu, or Covid-19.
In 2020, as the Covid-19 pandemic started to spread extensively, individuals implemented precautionary measures like wearing masks, practicing proper hand hygiene, and maintaining distance from others. Consequently, cases of flu infections drastically declined. While flu infections have seen a resurgence, it appears that the influenza B/Yamagata virus may have been eradicated due to these measures.
Experts advising the WHO have recommended for the 2024 Southern Hemisphere flu season to use trivalent vaccines that target three types of flu: two influenza A strains (H1N1 and H3N2) and an influenza B/Victoria strain. They have stated that including a B/Yamagata lineage component in quadrivalent vaccines, which target four types of flu, is unnecessary since no B/Yamagata infections have been identified in years.
"That's not to say that having it in the vaccine is bad, it's just no longer necessary or justified at this moment," stated David Wentworth, Director of the Collaborating Centre for Surveillance, Epidemiology, and Control of Influenza at the US Centers for Disease Control and Prevention, during the press conference. "Therefore, our recommendation is to eliminate that particular component."
On Wednesday, August 30, 2023, Bianca Perez, a nurse practitioner at CVS Minute Clinic in Miramar, Florida, administered a flu vaccine to Giselle Castillo-Righton of Miramar. (Carline Jean/South Florida Sun Sentinel/Tribune News Service via Getty Images)
Moderna claims its mRNA flu shot produces a more effective immune response, surpassing the efficacy of currently available vaccines. The constant evolution of flu viruses necessitates regular updates to flu vaccines. While the World Health Organization (WHO) provides recommendations to regulators and manufacturers globally, individual countries have the ultimate authority to decide which components to include. Typically, WHO issues recommendations for the Southern Hemisphere in September and for the Northern Hemisphere in February, allowing ample time for regulatory approval, vaccine production, and distribution before each hemisphere's flu season begins.
The advisers of the World Health Organization (WHO) report on the 2024 recommendations for the Southern Hemisphere flu vaccine have also taken into account the potential "theoretical risk of reintroduction into the population" that arises from using B/Yamagata viruses for vaccine manufacturing. The report suggests that this theoretical risk can be mitigated by excluding B/Yamagata from the vaccines. Kanta Subbarao, the director of the WHO Collaborating Centre for Reference and Research on Influenza at the Peter Doherty Institute for Infection and Immunity in Australia, stated that they are weighing the absence of Yamagata lineage virus circulation against the theoretical risk of manufacturing and using an unnecessary component.
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The flu vaccines currently being administered in the United States for this flu season consist of two influenza A viruses (H1N1 and H3N2) and two influenza B viruses, including a Yamagata lineage. Evidence from the previous Southern Hemisphere season suggests that these vaccines will be a good match for the viruses circulating during the fall and winter.
Advisers from the World Health Organization (WHO) emphasized the safety and effectiveness of flu vaccines, regardless of the formulation used by each country. It has been suggested that the US Food and Drug Administration is considering a possible shift to a trivalent vaccine for future flu seasons. However, such a change cannot be implemented overnight due to the necessary licensing and manufacturing adjustments.
The FDAs vaccine advisory committee is scheduled to meet October 5 to discuss recommendations for flu vaccines to be offered in the Southern Hemisphere in 2024.
