Adult Immunisation in a South Indian Tertiary Care Hospital: Who Benefits, What's Safe, and What Holds Us Back?

Adult immunisation is a critical yet underutilised public health strategy in India, despite the growing burden of vaccine-preventable diseases (VPDs) among adults. However, previous studies have explored awareness, knowledge, and acceptance of selected adult vaccines, a comprehensive understanding of utilisation patterns and vaccine-seeking behaviour remains limited.

A prospective observational study was conducted from April 2023 to February 2024 (10 months) at the Adult Immunisation and Travel Medicine Centre of a tertiary hospital. Adults aged ≥16 years who received at least 1 recommended vaccine were included, focusing on those outside the age group covered by the national immunisation programme. Data on demographics, immunisation status, comorbidities, and adverse events following immunisation (AEFIs) were collected. Statistical associations were analysed using the chi-square test (P < .05) and logistical regression.

A total of 1021 vaccine doses were utilised by 819 individuals. The most commonly utilised vaccines were Hepatitis B (62.03%), Influenza (10.99%), and Pneumococcal Conjugate Vaccine (PCV; 6.72%). The majority of recipients were female (58.97%), young adults (70.7%), healthcare workers (HCWs; 70.69%), and individuals from higher socio-economic classes (61.91%). Vaccine utilisation was 2.4 times higher among HCWs than non-HCWs. Partial immunisation was more common among young males (P < .0001) from non-HCWs (47.92%, 0.03) populations and those from lower-middle (67.93%, P < .0001) socio-economic classes. Only 1 serious Adverse Event (AE) was reported, later found to be unrelated with vaccination. Chi-square analysis revealed statistically significant associations between vaccine utilisation and variables such as gender, age, population type, socio-economic status, and comorbidities (P < .05).

Similar to global and national trends, adult vaccine coverage remained sub-optimal. However, among the limited users, only the economically advantaged sections of the community were able to afford and access immunisation, while vaccine-seeking behaviour was largely absent across wider segments of society.