Booster dose

In medicine, a booster dose is an extra administration of a vaccine after an earlier (prime) dose. After initial immunization, a booster injection or booster dose is a re-exposure to the immunizing antigen cell. It is intended to increase immunity against that antigen back to protective levels after it has been shown to have decreased after a specified period. For example, tetanus shot boosters are often recommended every 10 years. The need for a booster dose is evaluated in several ways, including the immune response after a booster dose is administered, active B and T cell activity after a certain amount of time that the primary vaccine was given, and prevalence of the disease in vaccinated populations. Anamnestic response, the rapid production of antibodies after a stimulus of an antigen, is a typical way to measure the need for a booster dose of a certain vaccine. If anamneestic response is high after receiving a primary vaccine many years ago, there is most likely little to no need for a booster dose.