Does vaccination against a disease confer active or passive immunity?

Active immunity is conferred when the body manufactures antibodies in response to direct contact with an antigen. When an individual is again exposed to the antigen, the body “remembers” it and mounts a quicker and more specific antibody response to that antigen. Active immunity can be conferred by exposure to the whole antigen (e.g., the chicken pox virus) or by vaccination with dead or weakened pathogens or altered toxins.

Passive immunity is conferred by the transfer of antibodies from one person to another; the recipient does not produce his or her own antibodies. For example, a gamma globulin shot (another individual’s antibodies) can confer passive immunity against hepatitis A. As another example, a fetus receives IgG across the placenta from the mother. This passive immunity helps the newborn to fight disease before its own immune system has developed.

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