Few studies have investigated the impact of immunization campaigns conducted under the global polio eradication program on sustainability of polio vaccination coverage, on coverage of non-polio vaccines (administered under Expanded Program on Immunization (EPI)), and on changes in social inequities in immunization coverage. This study proposes to fill the gaps in the evidence by investigating the impact of a polio immunization campaign launched in India in 1995.

The study uses a before-and-after study design using representative samples from rural areas of four North Indian states. The National Family Health Survey I (NFHS I) and NFHS II, conducted in 1992–93 and 1998–99 respectively, were used as pre- and post-intervention data. Using pooled data from both the surveys, multivariate logistic regression models with interaction terms were used to investigate the changes in social inequities.

During the study period, a greater increase was observed in the coverage of first dose of polio compared to three doses of polio. Moderate improvements in at least one dose of non-polio EPI vaccinations, and no improvements in complete immunization against non-polio EPI diseases were observed. The polio campaign was successful, to some extent, in reducing gender-, caste- and wealth-based inequities, but had no impact on religion- or residence-based inequities. Social inequities in non-polio EPI vaccinations did not reduce during the study period.

Significant dropouts between first and third dose of polio raise concerns of sustainability of immunization coverage under a campaign approach. Similarly, little evidence to support synergy between polio campaign and non-polio EPI vaccinations raises questions about the effects of polio campaign on routine health system's functions. However, moderate success of the polio campaign in reducing social inequities in polio coverage may offer valuable insights into the routine health systems for addressing persistent social inequities in access to health care.