Some oral poliovirus vaccines were contaminated with infectious SV40 after 1961
Cancer Res. 2005 Nov 15;65(22):10273-9.
Cutrone R, Lednicky J, Dunn G, Rizzo P, Bocchetta M, Chumakov K, Minor P, Carbone M.
Thoracic Oncology Program, Cardinal Bernardin Cancer Center, Loyola University, Chicago, Illinois, USA.
Some polio vaccines prepared from 1954 to 1961 were contaminated with infectious SV40. It has been assumed that all polio vaccines were SV40 free in the United States after 1961 and in other countries after 1962. Following a WHO requirement that was prompted by the detection of SV40 in some human tumors, we conducted a multilaboratory study to test for SV40 polio vaccines prepared after 1961. . . . All the vaccines were SV40 free, except for vaccines from a major eastern European manufacturer that contained infectious SV40. . . . These SV40-contaminated vaccines were produced from early 1960s to about 1978 and were used throughout the world. . . .