Flu Vaccine Strains. When autocomplete results are available use up and down arrows to review and enter to select. One influenza A H1N1 one influenza A H3N2 and one or two influenza B viruses depending on the vaccine are included in each seasons influenza vaccines.
The virus rapidly changes due to antigenic drift a slight mutation in the virus that causes a new strain to arise. Hence it should not require modification from year to year. However in most years 16 of the 19 years before 2007 the flu vaccine strains have been a good match for the circulating strains and even a mismatched vaccine can often provide cross-protection.
A universal flu vaccine is a flu vaccine that is effective against all influenza strains regardless of the virus sub type antigenic drift or antigenic shift.
Influenza A can be found in many species including humans birds and pigs. Two Influenza A viruses and two Influenza B viruses. Recommended composition of influenza virus vaccines for use in the 2020 southern hemisphere influenza season 27 September 2019. Getting a flu vaccine can protect against flu viruses that are like the viruses used to make vaccine.