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How has mass immunization reduced cases of poliomyelitis?

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Infographic showing estimated lives saved by childhood vaccinations worldwide from 1974 to 2024, with syringe-shaped bars for each disease. Measles tops the list at 93.71 million lives saved, followed by tetanus, whooping cough, and others, for a total of 153.84 million lives saved. — childhood disease and disorder Vaccines and the estimates of lives saved over the period 1974–2024.

Mass immunization has been instrumental in the global decline of poliomyelitis, a viral disease that historically caused widespread paralysis and death, particularly among children. The success of these efforts relies on two primary types of vaccines: the inactivated poliovirus vaccine (IPV), developed by Jonas Salk, and the oral poliovirus vaccine (OPV), developed by Albert Sabin.123

These vaccines work by stimulating the production of antibodies, which provide immune memory and enable the body to effectively neutralize the virus upon exposure. Mass vaccination programs, such as those integrated into the World Health Organization’s Expanded Program on Immunization, have successfully reduced the number of susceptible individuals in populations. By maintaining high vaccination coverage, communities achieve herd immunity, a state where the virus lacks sufficient hosts to sustain transmission, thereby protecting even those who cannot be vaccinated.3456

Through these coordinated global efforts, polio has been eliminated from most of the world, with endemic transmission currently limited to only a few regions.425