Intramuscular Injections within 30 Days of Immunization with Oral Poliovirus Vaccine — A Risk Factor for Vaccine-Associated Paralytic Poliomyelitis

Abstract

In Romania the rate of vaccine-associated paralytic poliomyelitis is for unexplained reasons 5 to 17 times higher than in other countries. Long ago it was noted that intramuscular injections administered during the incubation period of wild-type poliovirus infection increased the risk of paralytic disease (a phenomenon known as "provocation" poliomyelitis). We conducted a case-control study to explore the association between intramuscular injections and vaccine-associated poliomyelitis in Romania.