Are you protected if expired flu vaccine was used?

While an expired flu vaccine may not provide the same level of protection as a current one, it may still offer some protection. The human body's immune system is complex, and even if the vaccine is past its expiration date, it can still stimulate an immune response. However, the effectiveness of the vaccine may decrease over time, so it is always recommended to get the most recent flu vaccine.

The Centers for Disease Control and Prevention (CDC) recommends getting the flu vaccine every year, ideally by the end of October. This is because the flu season can begin as early as October and can last until May. Getting vaccinated early helps ensure the best possible protection throughout the flu season.

If you have any concerns about the effectiveness of an expired flu vaccine, it is best to consult with a healthcare professional. They can provide you with the most up-to-date information and recommendations.