Active versus Passive Immunity

Active immunity refers to the process by which an individual's immune system is stimulated to produce a protective response to a pathogen, typically involving the activation of both B cells and T cells. Active immunity can be acquired naturally through infection or artificially through vaccination.

Typically, vaccines contain dead or significantly weakened pathogens or their components. They offer functional antigenic determinants and stimulate the body to produce antibodies to combat natural infections of the same pathogen.

Vaccination can successfully eradicate diseases such as smallpox, whooping cough, polio, and measles. More recently, vaccines have played a crucial role in mitigating the impact of COVID-19.

However, in passive immunity, preformed antibodies are introduced directly into the body. Such protection only lasts until the antibodies naturally degrade.

Passive immunity can be obtained naturally, particularly in fetuses and infants, when antibodies from the mother pass through the placenta or by breast milk.

It can also be achieved artificially by introducing exogenous antibodies from an external source, such as IgG, from an immune donor's plasma.

This method is implemented to treat hepatitis A, venomous snake bites, botulism, rabies, and tetanus.