Path to full immunisation coverage, role of each vaccine and their importance in the immunisation programme: a cross-sectional analytical study of India.

Introduction: Immunisation is vital in preventing infectious diseases and promoting public health. This study examines the immunisation landscape in India, focusing on absolute zero dose (defined as a child did not receive any single dose of vaccine as per the National Immunisation Schedule), antigen-wise zero dose (defined as children who did not receive any dose of specific vaccine but received some or complete dose of other vaccines), the pattern of undervaccination (defined as children who missed any one or more than one dose of vaccine from total eight doses of vaccine (one dose-BCG, three doses-DPT, three doses-OPV and one dose-measles vaccine) and immunisation cascade. Methods: Using data from the National Family Health Survey-5, we analysed the immunisation status of 43 247 children across India. The prevalence of absolute zero-dose children, antigen-wise zero dose, co-coverage rates and cascade levels for vaccine combinations are assessed. The multilevel regression model has been applied to understand the likelihood of left-out and antigen-wise zero doses by socioeconomic determinants. Results: Children lacking vaccination cards experience a higher prevalence of absolute zero dose cases (21.2%). Notably, scheduled tribes (4.1%), the Muslim group (5.4%) and the poorest wealth quintile (4.6%) exhibit the highest prevalence. Remarkably, within partially vaccinated (20%) children, 42.8% show zero dose for measles-containing vaccines, while 6.7% of children failed to achieve full immunisation coverage due to just one missed dose of vaccine. Further, 20% of the partially vaccinated subset revealed that 7.29% missed full immunisation coverage due to oral polio vaccine (OPV) dose gaps. Conclusions: Targeted efforts are essential to bridge immunisation gaps and achieve universal coverage in India. Focusing on antigen-specific zero dose and partially vaccinated children, particularly those missing OPV doses and measles vaccine offers the potential to improve full immunisation coverage. Therefore, to achieve the IA2030 requires an intensified target for reaching absolute zero and antigen-wise zero dose.