Does a 4-year-old who received only one dose of Inactivated Poliovirus Vaccine (IPV) need to catch up, and if so, how far apart?

From the Guidelines

A 4-year-old who has only received one dose of inactivated polio vaccine (IPV) does need to catch up on their vaccination schedule. According to the guidelines outlined in the study published in Pediatrics in 2011 1, the child should receive three additional doses of IPV to complete the recommended series. The key points to consider for the catch-up schedule are:

• The minimum interval between doses 1 and 2 and between doses 2 and 3 is 4 weeks.
• The minimum interval between doses 3 and 4 is 6 months.
• The final dose in the inactivated poliovirus vaccine series should be administered at 4 through 6 years of age, regardless of the previous number of doses administered before the fourth birthday, and at least 6 months since the last dose was received.

Given these guidelines, the second dose should be given at least 4 weeks after the first dose, the third dose should be given at least 4 weeks after the second dose, and the fourth dose should be given at least 6 months after the third dose. This accelerated schedule ensures the child develops adequate immunity against poliovirus as quickly as possible while maintaining effectiveness, as emphasized in the study 1. Completing the full series is crucial because polio can cause permanent paralysis and even death, and while rare in most countries today due to vaccination efforts, the virus still exists in some parts of the world. The importance of maintaining high poliovirus immunity levels in children is highlighted in the study 1 to prevent outbreaks should poliovirus be imported into the country.

From the FDA Drug Label

Children The primary series of IPOL vaccine consists of three 0. 5 mL doses administered intramuscularly or subcutaneously, preferably eight or more weeks apart and usually at ages 2,4, and 6 to 18 months. Children and adolescents with a previously incomplete series of polio vaccine should receive sufficient additional doses of IPOL vaccine to complete the series. All children should receive four doses of IPV at ages 2,4,6 to 18 months, and 4 to 6 years.

A 4-year-old who has only received one dose of IPV needs to catch up.

• The child should receive the remaining three doses of IPV to complete the series.
• The exact timing of these doses is not specified in the label, but it is recommended that the primary series consists of doses administered eight or more weeks apart.
• It is also recommended that all children receive four doses of IPV at ages 2,4,6 to 18 months, and 4 to 6 years 2 2.

From the Research

Polio Vaccination Schedule

• The World Health Organization (WHO) recommends at least one dose of inactivated poliovirus vaccine (IPV) preceding routine immunization with oral poliovirus vaccine (OPV) to reduce vaccine-associated paralytic poliomyelitis (VAPP) and vaccine-derived polioviruses (VDPVs) 3.
• A study found that two doses of IPV given at 14 weeks and 9 months, or at 6 weeks and 9 months, resulted in a cumulative immune response of ≥99% to all three poliovirus types, which was significantly higher than the 77-81% observed with two doses given at 6 and 14 weeks 4.

Catch-up Vaccination

• If a 4-year-old child has only received one dose of IPV, they may need to catch up on their vaccination schedule, but the exact schedule would depend on various factors, including their age, health status, and the specific vaccination policies in their region 5, 6.
• A systematic review and meta-analysis found that routine immunization with 2 full or fractional doses of IPV given after 10 weeks of age is likely to protect >80% of recipients against poliomyelitis if poliovirus reemerges after withdrawal of OPV serotypes 6.

Immunogenicity of Sequential Vaccination Schedules

• A systematic review and meta-analysis found that sequential vaccination schedules with IPV and OPV resulted in non-inferior seroconversion rates and superior geometric mean antibody titers compared to IPV-only schedules 7.
• Another study found that sequential IPV-OPV schedules may reduce VAPP cases by 54% to 100% and have little or no difference in vaccination coverage, safety, or humoral response compared to OPV-only schedules 3.