Adult vaccination in India: A rapid review of current status & implementation challenges
Authors: Bhattacharyya Arunaloke , Shahabuddin Sheikh Mohammed 
Published: November 2024

Background & objectives
The expanded programme on immunization launched in India in 1978, with its focus on preventing six diseases in children (tetanus, diphtheria, pertussis, poliomyelitis, typhoid, and childhood tuberculosis), was widened in its scope in 1985-86. This new avtaar, the Universal Immunization Programme (UIP), incorporated measles vaccine for children and rubella and adult diphtheria vaccines for pregnant women. We conducted this rapid review on adult immunization relevant for India, as recent COVID-19 experience revealed how newly emergent or re-emergent pathogens could have their onslaughts on the elderly and adults with comorbidities.

Methods
Three different bibliographic databases, namely PubMed, Scopus and Ovid were searched electronically to access the articles published in peer-reviewed journals. Relevant consensus guidelines by in-country professional groups were also collated. We conducted deduplication and screening of the outputs of these searches (1242 bibliographical records). Finally, 250 articles were found eligible for inclusion. As trials on the reduction of morbidities, mortalities and hospitalizations in adults due to proposed vaccines under Indian consensus guidelines were not available, no meta-analysis was conducted.

Results
Evidence from articles finally included in this synthesis were grouped under (i) preventing viral and bacterial infections in adults; (ii) adult vaccination and awareness tools; (iii) vaccine hesitancy/acceptance; and (iv) adult vaccination guidelines. In-country research revealed the need for introducing the Human Papilloma Virus (HPV) vaccine in adolescence or early-adulthood to prevent ano-genital cancers in elderly and later life. Importantly HPV prevalence among cervical cancer patients varied between 88 to 98 per cent in Andhra Pradesh, Odisha and Delhi. The importance of conducting regular surveillance of pneumococcal diseases and influenza, as well as tweaking the vaccines accordingly, was revealed in other articles. A poor uptake of influenza vaccine (≤2%) in adults (≥45 yr) was documented.
The uptake of hepatitis B vaccine in Health Care Workers (HCWs) in Delhi and Mumbai was of concern and ranged from 55 to 64 per cent. The vulnerability of HCWs to rubella was investigated in a paediatric ophthalmic hospital in Madurai: a tenth of the selected HCWs were rubella seronegative and mounted good protective immunity following RA 27/3 vaccine administration. An outbreak of measles in college students in Pune emphasized the phenomenon of waning immunity. Similarly, a study in the infectious disease hospital in Kolkata and in-patients in Delhi revealed a lack of protective immunity against diphtheria and tetanus in adults. The researchers estimated the economic benefits of providing a typhoid vaccine to a household to be US$ 23 in a middle-income neighbourhood and US$ 14 in slum settings. The authors highlighted the importance of preventive strategies, finding that the cost of severe typhoid fever was US$ 119.1 in 18 centres across India. Both qualitative and quantitative investigations explored vaccine hesitancy, which was studied more during the COVID-19 pandemic than earlier.

Interpretation & conclusions
Vaccination programmes in India would require (i) increasing awareness around vaccine-preventable diseases among adults and HCWs; (ii) actively engaging health care systems and community-based organizations; and (iii) developing and producing affordable, safe, and country-appropriate vaccines. Effective communication strategies and tools will be the key to the success of such interventions.