The World Health Organization (WHO) Thursday recommended changes to the influenza vaccine composition for the 2015 influenza season (southern hemisphere winter), which includes replacing the A/H3N2 and B strains in trivalent vaccines.
The recommended composition for the 2015 vaccine includes A/California/7/2009 (H1N1)pdm09-like virus; A/Switzerland/9715293/2013 (H3N2)-like virus and a B/Phuket/3073/2013-like virus. It is recommended that quadrivalent vaccines containing two influenza B viruses contain the above three viruses and a B/Brisbane/60/2008-like virus.
According to a WHO Q&A published Thursday, “Increasing proportions of the recently circulating A(H3N2) and influenza B Yamagata-lineage viruses have undergone antigenic drift since the last vaccine recommendation.”
The WHO recommendations provide a guide to national public health authorities and vaccine manufacturers for the development and production of influenza vaccines for the next influenza season. In contrast to many other vaccines, the viruses in influenza vaccines have to be updated frequently because circulating influenza viruses continuously evolve. As it takes approximately 6-8 months to produce influenza vaccines, recommendations are made in September for the following influenza season in the southern hemisphere and in February for the following influenza season in the northern hemisphere. For more infectious disease news and information, visit and “like” the Infectious Disease News Facebook page