VACCINE-ASSOCIATED PARALYTIC POLIOMYELITIS IN THE UNITED-STATES - NO EVIDENCE OF ELEVATED RISK AFTER SIMULTANEOUS INTRAMUSCULAR INJECTIONS OF VACCINE

During the past 30 years, Romania reported rates of vaccine-associated paralytic poliomyelitis (VAPP) approximately 10-fold higher than in the United States. The elevated VAPP risk was largely caused by multiple intramuscular (im) injections with antibiotics given within 30 days of onset of paralysis. Because it is not known whether im injections contribute to the VAPP risk in the United States, we examined VAPP cases reported since 1980. We reviewed injection histories of VAPP cases reported to the Centers for Disease Control and Prevention from 1980 to 1993: with vaccines for 1980 to 1987; and for all substances for 1988 to 1993. Bates of VAPP by number of im injections with vaccines were calculated from 1988 to 1993 with estimated vaccine coverage data from the National Health Interview Survey, From 1980 to 1993 a total of 119 cases of poliomyelitis were reported to the Centers for Disease Control and Prevention. Of these, 87 (73%) were vaccine-associated and immunologically normal: 41 were oral polio vaccine (OPV) recipient cases; 40 were OPV contact cases; and 6 were community-acquired cases. A history of im injections in the 45 days before onset of paralysis was obtained from 28 (72%) of 39 recipient cases reported from 1980 to 1993 for which dates of paralysis onset could be determined and from 1 (8%) of 13 contact cases reported from 1988 to 1993. With one exception all substances administered intramuscularly were routine childhood vaccines, No clustering of im injections in the ''high risk'' windows, 0 to 3 and 8 to 21 days before onset of paralysis, was observed. From 1988 to 1993 the rates of recipient vaccine-associated paralytic poliomyelitis (VAPP) (per 1 million population) in infants <1 year of age did not vary significantly with the number of simultaneous im injections received, and ecologic analyses did not show increased risk with increasing use of injectable vaccines in children. Intramuscular injections of antibiotics or childhood vaccines did not appear to contribute to the risk of recipient VAPP in the United States, The low prevalence of im injections in contact VAPP cases suggests that the risk is attributable to OPV alone. Our study supports the current recommendation for the simultaneous administration of OPV with other childhood vaccines.