WHO recommends continued use of current flu vaccine strains

The World Health Organization recommended the continued use of the current three flu vaccine strains for the Northern Hemisphere’s next influenza season, which signals that these flu strains are likely to endure over the next few months.

The flu vaccines include an H1N1 component, which is a strain similar to A/California/7/2009, an H3N2 component, similar to A/Perth/16/2009, and a B component, which is a strain similar to B/Brisbane/60/2008-like virus, CIDRAP News reports.

Every February, the WHO meets to assess which flu strains are circulating around the globe before they recommend which strains should be used for the following season.

Six months are required for vaccine manufacturers to grow the viruses in chicken eggs and formulate them into trivalent vaccines, according to CIDRAP News.

The full report says that the 2009 H1N1 virus is still the dominant strain in Europe and some Asian countries. It recently topped H3N2 as the most dominant strain in the United States. H3N2 can be found circulating alongside influenza B in many parts of the world. Only five countries have reported cases of the former season of H1N1 virus.

Sporadic cases of H5N1 avian influenza cases have been reported from a few countries and no H9N2 cases have been reported from September to January, CIDRAP News reports. There have also been eight zoonotic infections caused by swine H3N2 and swine H1N1, with six in the United States and one each in Switzerland and China.