fIPV

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.