Which flu viruses does this season’s vaccine protect against?
Flu vaccines are designed to protect against three influenza viruses that experts predict will be the most common during the upcoming season. Three kinds of influenza viruses commonly circulate among people today: Influenza A (H1N1) viruses, influenza A (H3N2) viruses, and influenza B viruses. Each year, one flu virus of each kind is used to produce seasonal influenza vaccine.
The 2013-2014 trivalent influenza vaccine is made from the following three viruses:
- an A/California/7/2009 (H1N1)pdm09-like virus;
- an A(H3N2) virus antigenically like the cell-propagated prototype virus A/Victoria/361/2011;
- a B/Massachusetts/2/2012-like virus.