Routine Immunization Coverage Trends Before, During, and After the COVID-19 Pandemic: A Retrospective Ecological Analysis of Administrative Surveillance Data from Khyber Pakhtunkhwa, Pakistan

Abstract

Background: Maintaining routine health services during public health emergencies is essential for health system resilience. The COVID-19 pandemic disrupted immunization services worldwide, increasing concerns about declining vaccine coverage, zero-dose children, and resurgence of vaccine-preventable diseases. Evidence from Pakistan using administrative surveillance data remains limited. Objective: To describe temporal changes in routine immunization coverage among children aged under 24 months across pre-COVID-19, intra-COVID-19, and post-COVID-19 periods in Khyber Pakhtunkhwa, Pakistan. Methodology: A retrospective descriptive ecological study was conducted using aggregated secondary data from the Expanded Programme on Immunization Management Information System. Immunization records from all 28 reporting districts of Khyber Pakhtunkhwa from January 2019 to April 2022 were analyzed across three periods: pre-COVID-19, January 2019–February 2020; intra-COVID-19, March 2020–September 2021; and post-COVID-19, October 2021–April 2022. Results: Routine immunization coverage indicators demonstrated variation across the study periods. The proxy indicator for fully immunized children increased from 74% during the pre-COVID-19 period to 88% during the post-COVID-19 period, while the proportion of zero-dose children declined from 16% to 4%. Coverage for the major vaccine antigens also increased during the post-pandemic period, although BCG coverage exceeded 100%, reflecting administrative denominator limitations and programmatic factors rather than true population coverage. Conclusion: Routine immunization indicators derived from administrative surveillance data demonstrated improved programmatic coverage during the post-COVID-19 period in Khyber Pakhtunkhwa. These findings describe temporal patterns in routine immunization service delivery within a provincial immunization programme during and after the COVID-19 pandemic and provide evidence that may inform immunization programme planning and health system preparedness for future public health emergencies. The results should be interpreted in the context of aggregated administrative data and do not imply causal relationships between programme interventions and observed coverage changes. Keywords: Administrative Data, COVID-19, Ecological Study, Expanded Programme on Immunization, Health Systems, Khyber Pakhtunkhwa, Pakistan, Routine Immunization.