Polio Vaccination-Reply

In Reply.—  Drs Eggers and Mertens raise an important issue: Can even the small number of cases of poliomyelitis associated with oral poliomyelitis vaccine (OPV) be reduced by administering inactivated poliomyelitis vaccine (IPV) prior to OPV administration? Theoretically, induction of individual immunity by IPV should prevent recipient cases of vaccine-associated poliomyelitis. In support of this argument, two doses of an IPV with enhanced potency were found to bring about triple seroconversion in over 97% of recipients.¹ Nonetheless, approximately 60% of current vaccine-associated poliomyelitis cases occur in contacts of OPV recipients. Although IPV of current potency has been shown to reduce pharyngeal shedding of OPV virus following challenge, the effect on subsequent fecal excretion of OPV virus is variable and of unknown epidemiologic significance^2-4; the effect of an enhanced-potency product is apparently also limited (I. M. Onorato, MD, written communication, April 1987).There are also potential problems with combined