| Passive | Active | |
| MEANS OF ACQUISITION | Receiving preformed antibodies | Exposure to foreign antigens |
| ONSET | Rapid | Slow |
| DURATION | Short span of antibodies (half-life = 3 weeks) | Long-lasting protection (memory) |
| EXAMPLES | IgA in breast milk, maternal IgG crossing placenta, antitoxin, humanized monoclonal antibody | Natural infection, vaccines, toxoid |
| NOTES | After exposure to Tetanus toxin, Botulinum toxin, HBV, Varicella, Rabies virus, or diphtheria toxin, unvaccinated patients are given preformed antibodies (passive)—“To Be Healed Very RapiDly” | Combined passive and active immunizations can be given for hepatitis B or rabies exposure |