Core Concepts
Definition
- Fractional inactivated poliovirus vaccine constitutes one-fifth standard intramuscular dose.
- Dose volume strictly measures 0.1 mL.
- Administration requires intradermal route.
Rationale
- Dose-sparing strategy conserves limited global vaccine supply.
- Method reduces overall vaccination costs significantly.
- Two fractional doses provide superior immunogenicity compared to single full dose.
- Immunological response matches two full intramuscular doses effectively.
Immunization Schedule
Universal Immunization Programme
- Primary fractional doses given at 6 and 14 weeks.
- Third booster dose administered at 9 to 12 months.
- Initial 6 and 14-week doses injected intradermally into right upper arm at deltoid insertion.
- Booster at 9 months injected into left arm.
- Schedule operates concurrently with bivalent oral poliovirus vaccine given at birth, 6, 10, and 14 weeks.
Catch-Up Guidelines
- Incomplete fractional immunization requires transition to full intramuscular schedule.
- Single full intramuscular dose offered initially.
- Second full dose administered after minimum 8-week interval.
Efficacy And Immunogenicity
Seroconversion Rates
- Two fractional doses achieve 81% to 98% seroconversion against type 2 poliovirus.
- Median antibody titers remain highly protective despite being marginally lower than two full doses.
- Type 2 seroconversion and priming equal or exceed responses from single full dose.
Immunological Impact
- Induces robust systemic immunity against all three poliovirus types.
- Provides essential baseline immunity against vaccine-associated paralytic poliomyelitis.
- Protects populations against circulating vaccine-derived polioviruses.
- Mitigates critical immunity gaps following global cessation of type 2 oral poliovirus vaccine.
- Boosts intestinal and humoral immunity in prior oral poliovirus vaccine non-responders.
Storage And Handling
Temperature Requirements
- Maintain strict storage between 2°C and 8°C.
- Freezing damages vaccine formulation and diminishes potency.
Monitoring
- Highly sensitive to light and heat exposure.
- Vaccine vial monitors provide visual indications of cumulative heat damage.
- Monitor inner square color against outer circle to determine usability.
- Discard vaccine if inner square color matches or exceeds outer circle darkness.
