Abstract
<jats:p>Purpose: Childhood immunisation witnessed reduced coverage and delays globally during the Covid19 pandemic. This study aimed to identify gaps in routine childhood immunisation in southern India and the effect of the pandemic in censused rural and tribal populations. Methods: This study was conducted between August and September 2021 in a hard-to-reach tribal block (Jawadhu Hills) and rural (Timiri) block in Tamil Nadu. The proportion of full immunisation coverage (FIC), age-appropriate coverage and vaccination delays were calculated in the pre-pandemic (prior to March 2020) and pandemic (lockdown) period. Results: Among 2746 children (aged <30 months, with immunisation cards available) surveyed in these populations, overall FIC among children between 12-23 months of age was 50.8% (95%CI: 46.6-55.0) in Jawadhu and 83.7%; (81.1-86.2) in Timiri. In Jawadhu, coverage of oral polio vaccine3 (OPV3) decreased from 78.3% (73.4-82.6) pre-pandemic to 70.0% (66.6-73.2) during the pandemic; inactivated polio vaccine2 (IPV2) from 76.9% (72.1-81.2) to 69.1% (65.5-72.4); Pentavalent3 from 78.0% (73.1-82.4) to 70.2% (66.8-73.5); and Measles containing vaccine1 (MCV1) from 74.6% (67.6-80.8) to 56.7% (53.3-60.1). In Timiri, only MCV1 coverage decreased from 92.9% (88.7-95.9) to 85.4% (83.3-87.3). Factors associated with not receiving MCV1 included due date of vaccination falling during the pandemic lock downs, higher birth order, younger and less educated parents, and residing in the tribal block. Conclusion: This study highlighted differences in routine childhood immunisation vaccine coverage and impact of the pandemic in a geographically remote tribal block in contrast to a more accessible, rural block. Resilient health systems are essential to ensure sustainability in gains in vaccination coverage, especially in remote areas, and should be part of pandemic preparedness.</jats:p>