What does the term "booster dose" mean?

The term "booster dose" refers to a supplemental dose of a vaccine that is administered after the initial vaccination series to enhance or prolong the individual's immune response. The primary purpose of a booster is to remind the immune system of the pathogen, thereby increasing the levels of protective antibodies that may have diminished over time after the initial doses.

Immunity can wane, meaning that without a booster, a person's protection against certain diseases may decrease. By receiving a booster, the immune system is reactivated, which can help to maintain effective immunity against diseases, ensuring that the individual remains protected.

In contrast, the first dose of a vaccine is aimed at initiating the immune response (the start of the vaccination process), and there is no aspect of enhancing existing immunity involved. Similarly, a dose given merely to mitigate side effects does not align with the purpose of a booster. Lastly, while higher doses may be considered in specific scenarios, a booster dose is typically not characterized by a higher dosage for rapid immunity but rather by its role in reinforcing the immune defense.