Oral Poliovirus Vaccination in Children: A Study Suggesting Enterovirus Interference

Monovalent oral poliovirus vaccine type 1 was fed to two groups of children comparable in all respects except that in one group there was a high rate of naturally occurring infections with Coxsackie B4 and poliovirus type 3. Approximately 30% of the children in the latter group were found to have "wild" enteroviral infections during the two-week period beginning with vaccine feeding, and 38 of 128 of them (30%) who were "serologically susceptible" failed to show serologic evidence of vaccine "take" eight weeks after vaccination. In the other group, with no documented "wild" enteroviral infections during the two-week period, only three of 70 susceptibles (4%) failed to show a serologic response. This difference was attributed to the interfering effect of concurrent enterovirus infection on infection (and successful vaccination) with the OPV strain. Community vaccination programs scheduled in the cold months of the year should avoid the possibility of enterovirus interference.