Polio Vaccine Switch Has Lowered Rate of Vaccine-Associated Paralytic Disease

WESTPORT, CT (Reuters Health) May 18 - The incidence of vaccine-associated paralytic poliomyelitis has decreased since the September 1996 recommendation that inactivated poliovirus vaccine (IVP) should replace oral poliovirus vaccine (OPV) for the first two doses, according to an analysis of data from the Vaccine Adverse Event Reporting System.

Dr. Robert T. Chen of the Centers for Disease Control and Prevention in Atlanta and colleagues compared age-specific adverse event profiles of OPV and IPV for the periods from January 1991 to September 1996 and from October 1996 to December 1998. The findings are published in the electronic pages of the May issue of Pediatrics.

The reporting rate of adverse events related to poliovirus vaccines did not increase when the switch was made from OPV to IPV. The severity profiles and proportional distribution of adverse-event groupings tended to be similar for those who received IPV and those who received OPV.

The investigators noted a somewhat higher rate of death after IPV than after OPV, 0.83 versus 0.17 per 100,000 doses, most of which were due to sudden infant death syndrome. Nonfatal serious events occurred in 1.6 per 100,000 doses of IPV and 0.9 per 100,000 doses of OPV in 1998.

Since the switch to IPV, there have been five cases of vaccine-associated paralytic poliomyelitis among infants receiving OPV and none among those receiving IPV. Although allergic reactions were 2.5% higher for those receiving IPV, none of the reactions were anaphylactic.

"These findings provide useful information to support the Advisory Committee on Immunization Practices' recommendation to shift to an all-IPV schedule," Dr. Chen's team concludes.

Pediatrics 2001;107:e83.

http://www.pediatrics.org.