What viruses do 2016-2017 flu vaccines protect against?
There are many flu viruses and they are constantly changing. The composition of U.S. flu vaccines is reviewed annually and updated to match circulating flu viruses. Flu vaccines protect against the three or four viruses that research suggests will be most common. For 2016-2017, three-component vaccines are recommended to contain:
A/California/7/2009 (H1N1)pdm09-like virus,
A/Hong Kong/4801/2014 (H3N2)-like virus and a
B/Brisbane/60/2008-like virus (B/Victoria lineage).
Four component vaccines are recommended to include the same three viruses above, plus an additional B virus called B/Phuket/3073/2013-like virus (B/Yamagata lineage).