Incidence of heterologous antibodies in virus-confirmed cases of poliomyelitis.

RECENT laboratory studies of cases of poliomyelitis have demonstrated conclusively that the virus-confirmed disease occurs with much greater frequency in unvaccinated or inadequately vaccinated persons than among those with a history of three or more doses of poliomyelitis vaccine.1 2 3 These data, therefore, represent strong support of results observed in the original Field Trial4 of inactivated (Salk-type) vaccine. However, a definite proportion of virus-confirmed paralytic cases is seen each year among those with a history of three or more doses of vaccine. Since these occurrences are usually interpreted as failures of vaccination it is important to consider, if possible, whether they . . .