Three reasons: Three reasons: 1. Influenza viruses mutate over time, 2. the virus strains circulating can vary year to year, and 3. our immunity wanes over time.
Why does the flu vaccine have to be updated every year?
Why does the flu vaccine have to be updated…
Why does the flu vaccine have to be updated every year?
Three reasons: Three reasons: 1. Influenza viruses mutate over time, 2. the virus strains circulating can vary year to year, and 3. our immunity wanes over time.