Missed opportunities: Reducing zero dose children amongthe urban poor after COVID, Mumbai India, 2022.

Reaching urban poor populations poses challenges for equitable immunization coverage. Furthermore, COVID disrupted routine immunization services. In Mumbai, India, first dose diphtheria tetanus pertussis containing vaccine (DTPCV1)coverage dropped from 88% (2019) to 76% (2021). We identified and characterized 125 zero-dose (those withoutDTPCV1)migrant children in urban Mumbai in October 2022. Almost half were born elsewhere than Mumbai; 53% resided at their present location for less than a year. More than half were 12-59 months of age, well-beyond the age for first routine childhood immunizations.Three of four zero dose children had received birth dose vaccination in the hospital; but failed to receive DTPCV1. Vaccine hesitancy, awareness gaps and operational issues were common reasons for non-vaccination. Despite frequent visits to health facilities for illness,only a third of facility staff asked or advised parents about vaccination.Missed opportunities were much more common in private than government facilities.For the vast majority (88%), residential sites were included in local routine immunization micro-plans and distances to immunization sites were short (less than 1 km for 94 % of families).However, planned session frequency was inadequate half of the time. Expanded efforts to reach migrant urban poor children are needed to ensure vaccine equity.