Live, Orally Given Poliovirus Vaccine

The phenomenon of viral interference must be taken into account in planning the use of live poliovirus vaccine in areas where conditions favor the extensive dissemination of naturally occurring polioviruses. Experience with feeding a trivalent vaccine to 26,033 children in a tropical city of 100, 000 population led to the conclusion that interference was overcome by mass feeding of vaccine to 86% of all children under 11 years within a period of about four days, and that, because dissemination of the poliovirus was self-limited, a second feeding of trivalent vaccine was necessary to achieve immunization of almost all children. Recommendations are here formulated for the eradication of poliomyelitis, but they apply only to subtropical and tropical regions with extensive dissemination of various enteric viruses and not to temperate zones with good sanitation and hygiene during certain periods of the year and under conditions of low or absent dissemination of enteric viruses.