Examination of poliovaccines for the presence of SV40 sequences.

Batches of monovalent oral poliovirus vaccine bulks previously screened for infectious SV40 by cell culture methods and used in the United Kingdom from 1971-96 in trivalent oral poliovirus vaccine have now been examined by a newly developed PCR for the presence of SV40 sequences. Up to April 1997, over 190 batches have been examined. SV40 sequences were not detected in any of the vaccines. This provides additional assurance that oral poliovirus vaccines used in the U.K. from 1971 are free of SV40 contamination.