How are the viruses for the flu vaccine selected?

Each year, many laboratories throughout the world, including in the United States, collect flu viruses. Some of these flu viruses are sent to one of five World Health Organization (WHO) reference laboratories, one of which is at the Centers for Disease Control and Prevention (CDC) in Atlanta, for detailed testing. These laboratories also test how well antibodies made to the current vaccine react to the circulating virus and new flu viruses.

This information, along with information about flu activity, is summarized and presented to an advisory committee of the U.S. Food and Drug Administration (FDA) and at a WHO meeting. These meetings result in the selection of three viruses (two subtypes of influenza A viruses and one influenza B virus) to go into flu vaccines for the following fall and winter.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.