Community-Wide Type 3 Oral Poliovirus Vaccination in Atlanta, Ga., 1961

Four cases of paralytic poliomyelitis caused by Type 3 poliovirus had occurred in Atlanta, Ga., by mid-June, 1961. Their pattern of appearance, together with coincidentally-acquired laboratory evidence that wild Type 3 viruses were widely prevalent and that large numbers of children were susceptible, suggested that an epidemic was impending. A community-wide program of oral vaccination was instituted, and vaccine was administered to 285,000 children. During the week following, 3 cases occurred in vaccinees as a result of prevaccination infection, and only 4 additional cases, in nonvaccinees, during the remainder of the year. From this result, and from extensive laboratory studies of naturally-occurring and vaccine-derived enteroviruses, it was concluded that an epidemic probably had been developing, and that the use of the vaccine aborted it.