US CDC Advises Injected Polio Vaccines

The Centers for Disease Control in the USA has changed, for the first time since 1961, the guidelines regarding administration of polio vaccine.

After two years of study, the CDC has recommended that children receive the polio vaccine in a combination of inactivated and oral formulations. Under this schedule, infants will be injected with the inactivated polio virus twice in their first four months, followed by two oral doses between one and six years of age. OPV is the only form which stimulates mucosal immunity. The polio virus is transmitted via the alimentary canal, so mucosal immunity is particularly important (Marketletter July 31, 1995).

CDC Urges Change To IPV Currently, most children receive four doses of oral vaccine by the age of two, but in June an advisory panel to the CDC urged the change because of eight to 10 polio cases in the USA every year in adults and children resulting from the oral vaccine, in which the virus is in a live but weakened form. The panel says that a switch to IPV should be made. This is a stronger version of the vaccine which causes only serum immunity, but does not prevent a carrier from infecting the unimmunized. The sequential schedule combining both IPV and OPV would therefore stimulate both serum and mucosal immunity.