ACIP amends poliovirus vaccine recommendations
Members of the Advisory Committee on Immunization Practices affirmed a recommendation for a fourth dose of inactivated poliovirus-containing vaccine for 4-to-6-year olds if the three-dose vaccine series is completed before the child is 4.
“The reason for this proposal from the work group has to do with the continued threat of importation from the fact that polio has not yet been eradicated, but also due to incomplete data on the duration of immunity into adulthood with the last dose of inactivated polio vaccine administered at age 15 to 18 months,” Gregory S. Wallace, MD, MS, MPH, a medical officer in the CDC’s National Center for Immunization and Respiratory Diseases said during the ACIP meeting held here in Atlanta.
A footnote will be added to the routine schedule stating that final dose of inactivated poliovirus vaccine should be administered “on or after the child’s fourth birthday.”
“Age and dose intervals affect antibody response,” Wallace explained. “A schedule based on two, four and six month intervals induces higher seroconversion rates than a two, three, and four month schedule or a six, 10 and 14 week schedule.”
Longer intervals between doses are optimal in order to create a sufficient booster response, according to Wallace.
A fourth dose remains unnecessary if the third dose in the series was administered at or after a child is aged 4 years, if at least six months have passed between the second and third doses.
Revisions to the catch-up schedule
A footnote will also be added to the catch-up schedule stating that minimum age and interval requirements for polio vaccination are only recommended for children aged 6 months and younger if the child is at risk for “imminent exposure” to circulating virus, such as when traveling to an endemic region or in the event of a polio outbreak.
“The concern has been that minimum intervals are being used inappropriately to accelerate the schedule,” Wallace said.
The minimum age requirement for the first catch-up dose of inactivated poliovirus vaccine remains the same at 6 weeks, with a minimum four week interval between the first and second, and second and third doses. If a fourth dose is necessary, a minimum interval of six months is recommended. – by Nicole Blazek
For more information:
Wallace GS. Updated recommendations for routine poliovirus immunization. Presented at: the Advisory Committee on Immunization Practices Meeting; June 24-26, 2009; Atlanta.
