Global Eradication of Poliovirus:History and Rationale

Poliovirus is highly transmissible, with only 1 of every 100 to 1,000 infections among susceptible individuals resulting in clinically recognizable disease. The origin of global eradication of poliomyelitis is conventionally attributed to Albert Sabin and his colleagues in the frequently quoted and often reprinted 1960 report on the effects of rapid mass oral polio vaccine (OPV) immunization in Toluca, Mexico. For many, smallpox eradication would be a fluke in the annals of public health. No other infectious diseases were thought to share the unique characteristics that made it possible to eradicate smallpox: clinically apparent disease; low agent transmissibility; and an effective, inexpensive, and easily administered vaccine. The eradication of smallpox had proven the value of program goals based on disease outcome rather than service coverage. As with smallpox eradication, one of the anticipated major benefits of polio eradication is the cessation of immunization. Unlike the live smallpox (vaccinia) vaccine strain, Sabin OPV strains commonly spread from vaccinees to close nonimmune contacts and are genetically unstable, regaining certain wild virus characteristics upon replication in the human gut. The only way to fully control poliomyelitis in the developing tropical world with limited health infrastructure is to interrupt virus transmission through mass OPV immunization. Global eradication is a natural outcome.