A state of having protection against a pathogen so that even with exposure, an individual with immunity may not become infected with the disease or will experience diminished clinical symptoms and/or improved disease outcome after infection.

  • Active immunity: Immunity developed by the host (through infection and recovery or vaccines). Antibody is produced by the host.
  • Passive immunity: Immunity is acquired by receiving antibodies against a pathogen naturally from mother to offspring (i.e., through placenta or breastfeeding) or artificially (e.g., immunoglobulin treatment).