Do you need to get the flu vaccine every year once you start getting it?

Once the flu vaccine is administered, it usually needs to be taken annually; however, individuals who are allergic to the vaccine or have issues with their immune system may not need to receive it every year. If in doubt, it is recommended to consult a healthcare professional in advance. Detailed explanations are as follows:

Influenza viruses are highly variable, and the prevalent strains may differ each year. Therefore, even if someone received a flu vaccine the previous year, the antibodies produced may not effectively protect against the new strains circulating in the following year. Additionally, the protective effects of the flu vaccine typically last only about a year. Over time, antibody levels in the body gradually decline, and the protective effect weakens. Thus, to maintain immunity against influenza viruses, annual vaccination is necessary.

However, some individuals may be allergic to the flu vaccine or may not mount an effective immune response due to immune system problems. For these individuals, receiving the flu vaccine may not provide the expected protection and could even trigger allergic reactions. Furthermore, if a person has already been infected with the influenza virus and recovered within the past year, they may already have developed antibodies against that particular strain, and thus might not need to be vaccinated again that year.

At the same time, it is important to maintain good personal hygiene habits in daily life, such as washing hands frequently, wearing masks, and avoiding crowded places to reduce the risk of infection with influenza viruses.