The first large-scale vaccination campaign using needle-free jet injectors to administer fractional doses of inactivated poliovirus vaccine (fIPV) was conducted in Karachi, Pakistan, in February 2019. Data on acceptability of jet injectors were collected from 610 vaccinators and 4898 caregivers during the first four days of the campaign. Of those with prior needle and syringe experience, both vaccinators and caregivers expressed a strong preference for jet injectors (578/592 [97.6%] and 4792/4813 [99.6%], respectively), citing ease of use, appearance, and child’s response to vaccination. Among caregivers, 4638 (94.7%) stated they would be more likely to bring their child for vaccination in a future campaign that used jet injectors. Mean vaccine coverage among towns administering fIPV was 98.7% – an increase by 18.4% over the preceding campaign involving full-dose IPV. Our findings demonstrate the strong acceptability of fIPV jet injectors and highlight the potential value of this method in future mass campaigns.
