How long does the flu vaccine last?

Feb 11, 2025 Source: Cainiu Health

Dr. Ren Yi

Introduction

After receiving the influenza vaccine, the body develops antibodies within approximately 14 days. These antibodies help fight against the influenza virus, thereby reducing the risk of infection. Over time, antibody levels gradually decline, and generally, re-vaccination with the seasonal influenza vaccine is needed every 8 to 12 months. It is recommended to receive the annual influenza vaccine 1 to 2 months before the onset of the flu season.

Generally, the effectiveness of the flu vaccine lasts around 8 to 12 months. If there are any concerns, it is recommended to consult a healthcare professional in advance. Detailed explanations are as follows:

After receiving the flu vaccine, the body typically develops antibodies within approximately 14 days. These antibodies help combat the influenza virus and thereby reduce the risk of infection. However, over time, the antibody levels in the body gradually decrease, and generally, the flu vaccine needs to be re-administered every 8 to 12 months.

If the vaccine recipient is older or has a weaker constitution and does not take proper care after vaccination—for example, frequently visiting crowded places—the duration of vaccine effectiveness in the body may be relatively shorter, lasting about 8 months.

Conversely, if the recipient is younger and has a stronger constitution, and takes proper care after vaccination—such as undergoing regular medical checkups and engaging in appropriate physical exercise—the vaccine may remain effective in the body for a longer period, potentially up to 12 months.

To effectively prevent influenza, it is recommended to receive the annual flu vaccine 1 to 2 months before the onset of flu season. Additionally, during peak flu season, other preventive measures should also be taken, such as wearing masks, washing hands frequently, and avoiding crowded places, to reduce the risk of infection.

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