What strain of influenza is the seasonal flu?

There are many different strains of influenza, which are constantly evolving. The seasonal flu vaccine is designed to protect against the most common strains that are expected to circulate in a given season. The strains included in the vaccine are chosen based on data from global influenza surveillance, which tracks the spread of influenza viruses around the world.

For the 2022-2023 Northern Hemisphere influenza season, the following strains are included in the seasonal flu vaccine:

* A/Victoria/2570/2019 (H1N1)pdm09

* A/Darwin/9/2021 (H3N2)

* B/Austria/1359417/2021 (Yamagata lineage)

* B/Phuket/3073/2013 (Victoria lineage)

These strains were chosen based on the World Health Organization's recommendations, which are based on data from global influenza surveillance. The vaccine is designed to provide protection against these strains, but it is important to note that it is not 100% effective. It is still possible to get the flu even if you have been vaccinated, but vaccination can reduce your risk of severe illness, hospitalization, and death.