Topic overview

Start with the big picture

This topic introduces the main vaccine classes and how they stimulate immunity. Live-attenuated vaccines can provide long-lasting protection but are unsuitable for some people, including those who are pregnant or profoundly immunosuppressed. Inactivated and subunit vaccines are safer in these groups but may need additional doses or boosters. Toxoid vaccines target bacterial toxins, while conjugate vaccines help generate T-cell–dependent responses to polysaccharide antigens. The lesson also covers newer mRNA and viral-vector platforms, the role of adjuvants, and how vaccination coverage can interrupt transmission. Safety and delivery considerations include contraindications, spacing of certain vaccines, coadministration, cold-chain storage, and adverse-event monitoring.