The coronavirus pandemic is also impacting other infectious diseases. For example, a strain of flu has apparently completely disappeared from the scene. Type B/Yamagata pathogens have not been found worldwide since late March. Therefore, it should no longer be included in flu vaccines in the future.
The coronavirus SARS-CoV-2 is still in circulation, but has apparently replaced the flu strain B/Yamagata. The World Health Organization (WHO) and the US Food and Drug Administration (FDA) therefore recommend omitting this component from future flu vaccines.
The current quadruple vaccines against influenza currently contain two antigens for influenza A viruses (A(H1N1)/derived from “swine flu” for both the Northern Hemisphere (2023/2024) and planned for the Southern Hemisphere (2024). /2009 and an antigen of A(H3N2) viruses. In addition, there are two antigens of influenza B pathogens (for the “Victoria” pathogen line, an antigen of the B/Austria strain/2021) and for the so-called B/Yamagata Pathogen line contains the antigen from a 2013 B/Phuket strain.
WHO: “Yamagata currently has no advantage in the vaccine”
But at the end of September – apparently as a long-term consequence of the Covid 19 pandemic – the course was reset. The WHO has decided to withdraw the recommendation for antigens from the B/Yamagata pathogen lineage in influenza vaccines. “There is currently no benefit to Yamagata from the vaccine,” David Wentworth, director of the WHO Global Influenza Surveillance Network, told US pharmaceutical information service Stat.
Corona measures also had consequences for flu waves
The reason for this: The B/Yamagata flu virus family has not been observed since March 2020. The prevention measures resulting from the Covid-19 pandemic, with mandatory masks and restrictions on social contacts, etc., caused a sharp decline in the strength of seasonal flu waves worldwide. At the same time, this apparently also had an impact on the pathogen strains: certain A(H3N2) variants occurred only rarely.
Virologist Krammer: Pathogens in vaccines are no longer useful
B/Yamagata – one of two influenza B pathogen lines – could have literally gone extinct with Covid-19. “The others – H1, H3 (both influenza A variants; note) and Victoria (flu B; note) have come through. “But there was apparently such a big bottleneck for the Yamagata viruses that they did not survive,” said Austrian-born virologist Florian Krammer (New York). In any case, there is no point in having an antigen from a pathogen in a vaccine that is no longer common.
Last Thursday, the US Food and Drug Administration (FDA) expert panel responsible for flu vaccines also endorsed the WHO recommendation. The B/Yamagata antigens should be removed from subsequent vaccines as soon as possible. It is already too late for flu vaccines for the Southern Hemisphere (2024, in the Northern Hemisphere summer). The question remains what might need to be used to replace B/Yamagata for the Northern Hemisphere influenza vaccine for the 2024/2025 season. It is possible that antigens from another A/H3N2 virus strain could be added to increase effectiveness.
Source: Krone
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