Booster shots are intended to bolster the effect of the initial dose(s) of the vaccine. Data has shown that after several months the effectiveness of the vaccine, while still substantial, does decline somewhat. This does not mean that the vaccine is no longer working. According to the CDC, the COVID-19 vaccines still work very well to prevent severe illness, hospitalization, and death, even against the widely circulating Delta variant. However, with the Delta variant, public health experts are starting to see reduced protection against mild and moderate disease. The booster shots will help vaccinated people maintain that protection over the coming months.
The recent emergence of the Omicron variant makes booster shots even more important. Scientists around the world are studying vaccine effectiveness related to this variant, which appears to be highly transmissible. According to the CDC, strong immunity will likely prevent serious illness, and the CDC recommends that everyone 18 and older receive a booster either when they are six months after their initial Pfizer or Moderna series or two months after their initial Johnson & Johnson vaccine.
Booster shots are used for many types of vaccines, such as for tetanus or whooping cough. Unlike an additional dose of vaccine that is given to individuals who are immunocompromised and do not build up enough protection when they get the initial vaccination, booster doses are given to people who have built enough protection after their vaccine, but that protection decreases over time, a situation called waning immunity.
Talk with your health care provider about any questions or concerns you have about getting a COVID-19 vaccine booster shot.