Addressing the inactivated poliovirus vaccine shortage

BACKGROUND: Intradermal administration of fractional inactivated poliovirus vaccine (fIPV) is a dose-sparing alternative to intramuscular full dose. We assessed the recommendation of two fIPV doses or one IPV dose for routine immunization, and a fIPV booster dose for outbreak response. METHODS: We conducted an open-label, randomized, controlled, inequality, non-inferiority trial in two Dhaka clinics, Bangladesh. Healthy infants were randomized at 6 weeks to one of four arms: (A) IPV at 14 weeks and IPV at 22 weeks (booster); (B) IPV at 14 weeks and fIPV booster; (C) IPV at 6 weeks and fIPV booster; or (D) fIPV at 6+14 weeks and fIPV booster. Vaccines were administered by needle-syringe, with intradermal adapter for fIPV. Vaccine response (seroconversion from seronegative (