Immunity to a disease is categorized by ACIP into which two types?

• A. Active and Passive
• B. Humoral and Cellular
• C. Innate and Adaptive
• D. Local and Systemic

Answer: (A)

The main idea here is how immunity is categorized by source and duration in vaccine practice: active versus passive. Active immunity happens when the body's own immune system is stimulated to respond to an antigen, such as through infection or vaccination. This response builds immunological memory, so protection tends to be long-lasting, often years or a lifetime. Passive immunity, on the other hand, is created when antibodies are provided from an external source, such as maternal antibodies passed through the placenta or breast milk, or through immune globulin administration. It offers immediate protection but is temporary because the body doesn’t develop its own memory immune response.

This distinction is what ACIP uses when talking about immunity in the context of vaccines and protection strategies. It’s different from other ways of describing immunity, like humoral versus cellular (which refers to antibody-mediated versus cell-mediated components) or innate versus adaptive (which describes immediate nonspecific defense versus learned responses). The active-versus-passive framework is the practical, policy-relevant way to describe how protection is acquired and how long it lasts.