Poliomyelitis Vaccine

The last four years have witnessed a marked decline in the reported cases of poliomyelitis, for which the Salk vaccine has been largely responsible. Indeed, the relative decrease of paralytic disease caused by the three polioviruses has brought into relative prominence a whole host of less virulent, neurotropic enteroviruses whose numbers are increasing as fast as diagnostic laboratories can take the time to identify them. However, 301 cases of paralytic poliomyelitis were reported in the continental United States during the first nineteen weeks of 1959,1 not all of which occurred in unvaccinated persons. In addition, during the period in which . . .