Routine immunization coverage in Pakistan: a survey of children under 1 year of age in community-based vaccination areas.

Pakistan is one of two countries in which poliovirus remains endemic. Considering the high number of children born every year, reaching and vaccinating new birth cohorts by improving routine immunization coverage in children <1 year of age is crucial to halting virus transmission. In 2015, a community-based vaccination (CBV) strategy, using local community members to enhance vaccine acceptance and improve routine immunization service delivery, was introduced in areas of Pakistan that have never interrupted poliovirus transmission. In order to assess progress towards improving routine immunization, we performed house-to-house immunization surveys across ten CBV areas in 2017 and 2018. In each household, we determined age-appropriate routine antigen coverage for children <1 year of age based on vaccination card and caregiver recall. We surveyed 5,499 and 5,264 children in 2017 and 2018, respectively. Overall, coverage of inactivated poliovirus vaccine (IPV) at 14 weeks of age was 32% in 2017 and 39% in 2018 based on vaccination card and recall. Across the surveyed areas, coverage ranged from 7% in Killa Abdullah to 61% in Peshawar in 2018. Oral poliovirus vaccination coverage decreased with successive vaccination visits, ranging from 66% for the birth dose to 42% for the 14-week dose in 2018. No area reached the target of 80% coverage for any routine antigen. Our findings highlight the need for concerted efforts to improve routine immunization coverage in these critical areas of wild poliovirus transmission.