World Health Organization (WHO) Recommends Removal of Extinct Influenza Strain Component from Vaccines
In a move aimed at optimizing the efficacy of seasonal influenza vaccines, the World Health Organization (WHO) has advised the removal of a specific component that protects against an extinct strain of the virus, B/Yamagata lineage. The recommendation comes as the B/Yamagata lineage has not been detected since March 2020, which experts believe is a result of the COVID-19 pandemic’s disruption of the spread and cycles of other infectious diseases.
The 2020-2021 flu season was virtually nonexistent, leading to a substantial collapse in the genetic diversity of circulating flu strains. As a result, WHO advisors have suggested excluding the B/Yamagata component from the 2024 influenza seasonal vaccine for the southern hemisphere. The absence of the B/Yamagata lineage indicates a very low risk of infection, and including the vaccine component could potentially reintroduce the virus.
Prior to its disappearance, there were four types of seasonal flu that circulated globally, and vaccines targeted three or four of them. The United States, which utilizes quadrivalent shots, currently administers flu shots for the 2023-2024 season that contain a B/Yamagata component. However, with the WHO’s recommendation, future vaccines will likely exclude this component to ensure maximum effectiveness against currently relevant strains.
This decision is based on extensive research and surveillance conducted by international health organizations, which constantly monitor the evolution and circulation of influenza viruses. By adapting vaccine formulations to match the prevalent strains and removing unnecessary components, experts seek to provide individuals with the most efficient protection against influenza and reduce the likelihood of outbreaks.
It is important to note that the exclusion of the B/Yamagata component does not compromise the overall effectiveness of the flu vaccine. Seasonal vaccines are regularly updated to reflect the prevailing strains, ensuring that individuals receive adequate immunity against the most threatening viruses.
As the world prepares to face future flu seasons, the WHO’s expert recommendations will serve as a guiding principle for healthcare providers and vaccine manufacturers worldwide. Adhering to these guidelines will enable the provision of flu vaccines that are finely tuned to the prevailing strains, thus safeguarding public health and mitigating the impact of influenza outbreaks.