Which type of vaccine typically requires multiple boosters to achieve effective immunity?

Inactivated vaccines often require multiple boosters to achieve effective immunity due to their nature. These vaccines are made from pathogens that have been killed or inactivated so they cannot cause disease. Because inactivated vaccines do not replicate in the host, the immune response they elicit tends to be weaker and shorter-lived compared to live vaccines. As a result, to boost and maintain immunity over time, these vaccines usually require a series of doses, or boosters, to enhance the immune response and provide adequate protection.

Live vaccines, on the other hand, contain a weakened form of the pathogen and often produce a stronger and longer-lasting immune response after just one or two doses. Subunit vaccines consist of pieces of the pathogen, and while they can sometimes require boosters, they do not necessarily do so as often as inactivated vaccines. DNA vaccines, which involve introducing pieces of DNA coding for immune targets, can generate strong responses without requiring multiple doses in some cases. Each type of vaccine plays a specific role in immunization strategies, but inactivated vaccines are particularly notable for the requirement of booster shots to ensure effective immunity.