Fractional-dose IPV (fIPV) administered intradermally at 1/5th the full dose is used in India primarily for which reason?
- A To conserve vaccine supply while maintaining adequate seroconversion for all three poliovirus serotypes ✓
- B It produces a stronger mucosal immune response than full-dose IPV
- C It reduces the rate of vaccine-associated paralytic polio (VAPP)
- D The intradermal route bypasses cold chain requirements entirely
Correct answer: A. To conserve vaccine supply while maintaining adequate seroconversion for all three poliovirus serotypes
Explanation
India introduced fractional-dose IPV (1/5th dose, 0.1 mL intradermal) at 6 weeks and 14 weeks in the UIP schedule primarily as a dose-sparing strategy given global IPV supply constraints and high cost. Studies have shown that two fractional intradermal doses achieve seroconversion rates comparable to one full intramuscular dose for all three serotypes. This allows broader immunization coverage without sacrificing immunogenicity, particularly important in countries with high polio-risk.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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