Background Inactivated Polio Vaccine (IPV) campaign was conducted in February 2019 in Karachi where needle-free injectors were introduced for the administration of the fractional dose of IPV (fIPV) on a large scale. This study aimed to determine the impact of needle-free injectors on vaccination coverage. Methods In four towns of Karachi, fIPV was given using needle-free injectors “PharmaJet Tropis ID”. Whereas, in six towns full dose of IPV was administered to children of 4–59 months of age. Cluster surveys through rapid convenience assessment method were conducted after the completion of vaccination activity. Results A total of 33,815 households’ data was analyzed. Among these, 27,650 (82.8%) children were vaccinated. In fIPV areas, 85.3% of children were vaccinated compared to 79.5% in full dose IPV areas. A comparison of reasons for unvaccinated showed that 1.6% of parents do not give importance to vaccination in fIPV areas compared to 4.2% in full IPV areas (p-value < 0.0001). More children were not vaccinated due to fear of injection 1.8% in full IPV areas compared to 0.7% in fIPV areas (p-value < 0.0001). The source of campaign information shows that more frequent mobile miking 3.1% was observed in fIPV areas compared to 0.4% in full IPV areas (p-value < 0.0001). Conclusions Our analysis supports the fractional dose of IPV in mass campaigns to achieve good vaccination coverage especially using needle-free injectors “PharmaJet Tropis ID” and vigorous social mobilization activities are expedient in accomplishing high coverage.

The study aimed to determine the reasons for polio vaccine hesitancy among parents of persistently missed children (PMCs) in the high-risk areas of Karachi, Pakistan. A cross-sectional survey of parents of PMCs was conducted in April 2019 in 34 high-risk union councils of Karachi. PMCs were randomly selected from the polio program database, and further information was collected on a questionnaire by trained staff using face-to-face interviews with parents of PMCs. A total of 325 participants were included in the study. Among refusals, 112 (37.3%) had no trust in vaccine quality, followed by 45 (15.0%) who were afraid of side effects, 42 (14.0%) whose elders did not allow polio vaccination, 39 (13.0%) who refused due to the influence of negative social media videos, and 20 (6.7%) who had no trust in polio teams. We concluded that misconception is still a big challenge, and the program needs to strive for community acceptance. Low levels of trust in vaccines and teams as well as fear of OPV side effects were among the main reason for vaccine hesitancy. The participant communities recommended involving famous medical doctors, religious influencers, and TV or sports stars to enhance knowledge and acceptance of polio vaccination.