Immunization is regarded as one of the most cost-effective public health interventions, preventing an estimated 3.5 to 5 million deaths every year across all age groups. While childhood immunization has received sustained programmatic attention through India's Universal Immunization Programme, adult immunization continues to remain a relatively neglected area of preventive medicine, both in public awareness and in routine clinical practice. Adults are susceptible to a range of vaccine-preventable diseases either because childhood immunity wanes over time, because certain vaccines (such as influenza, pneumococcal and herpes zoster vaccines) are specifically recommended only in adulthood or old age, or because of acquired risk from comorbidities, occupation, travel or pregnancy. Ageing itself is associated with immunosenescence, which increases susceptibility to infections such as influenza, pneumonia and herpes zoster and their complications. Despite this, coverage of adult immunization in India remains low, and there is a paucity of nationally endorsed guidelines and implementation policy for adult vaccination. Several Indian studies over the past two decades illustrate this gap. An early cluster survey on immunization knowledge, attitude and practice conducted among caregivers of children in urban slums of Lucknow highlighted that knowledge gaps and misconceptions about vaccination are a long-standing and measurable phenomenon in Indian communities, and established the KAP survey as a robust tool for guiding local immunization strategy. More recent work has extended this approach specifically to adult vaccination. A tri-service study among adults in Western India found generally poor awareness of adult vaccines, attributing this partly to affordability, limited availability and low perceived susceptibility to vaccine-preventable illness, and noted that educational status was directly correlated with better knowledge and uptake.1 Studies among healthcare professionals — who are expected to be both informed recipients and active promoters of adult immunization also reveal important gaps. A survey among postgraduate resident doctors in a tertiary hospital in Navi Mumbai found that more than a quarter of residents were unaware that a formal adult immunization schedule even exists, although awareness hepatitis B vaccines was high.2 A larger, two-centre KAP study among 500 doctors and nurses in the Malabar region of Kerala similarly found that while a majority of healthcare professionals were at least partially aware of adult immunization recommendations, complete awareness and consistent practice were considerably lower, with medical faculty and continuing medical education identified as the dominant sources of information.3 A multicentre online KAP study coordinated through AIIMS Rishikesh, focusing specifically on vaccination of older adults, similarly reported that healthcare professionals' knowledge and practice patterns related to vaccinating adults aged 60 years and above remain limited despite international recommendations.4 In Western Uttar Pradesh, a KAP survey among MBBS students found that just over half demonstrated complete knowledge of the hepatitis B vaccine, while awareness of cholera and herpes zoster vaccines was strikingly low, even though a majority of students believed adult immunization was underutilised in India.5 The KAP gap is not confined to healthcare providers. Vaccine hesitancy among doctors and their own family members has been documented in Delhi, underscoring that even professional exposure to medicine does not automatically translate into personal vaccine uptake. Similarly, an exploratory survey among the general adult population attending a tertiary care hospital in Hyderabad found that structured educational interventions could measurably improve subsequent vaccine consumption, suggesting that the knowledge-practice gap is modifiable with targeted awareness efforts.6 Vaccine-specific KAP research, such as a nationwide survey of pediatricians regarding adult pneumococcal vaccination published in the Journal of the Association of Physicians of India, has further shown that even specialist knowledge of specific adult vaccines can be inconsistent, reinforcing the need for continuing medical education across all levels of the healthcare workforce.7 Given this backdrop of a well-documented but still incompletely understood knowledge-attitude-practice gap, the present study was undertaken to systematically assess the knowledge, attitude and practice pattern regarding adult immunization in study population, and to identify factors associated with inadequate uptake, in order to inform locally relevant awareness and intervention strategies. Objectives • To evaluate the attitude of participants toward adult vaccination. • To determine the actual practice pattern of adult vaccine uptake. • To identify sociodemographic and clinical factors associated with knowledge, attitude and practice scores.

Study Design and Setting This was a cross-sectional, questionnaire-based, descriptive observational study conducted in the Department of General Medicine & Pharmacology of Venkateshwara Institute of Medical Sciences, Gajraula, a tertiary care teaching hospital, over a period of 1 year. Study Population The study included adults aged 18 years and above attending the outpatient department of General Medicine. who consented to participate. Individuals who were critically ill, unwilling to give consent, or unable to comprehend the questionnaire were excluded. Sample Size Taking the prevalence of adequate knowledge regarding adult immunization from a comparable previous study as approximately 40%, with an absolute precision of 5% and a 95% confidence level, the minimum calculated sample size using the formula n = Z²pq/d² was 369, rounded up to 400 to account for non-response. Sampling Technique Participants were enrolled by consecutive convenience sampling from eligible individuals until the calculated sample size was achieved. Study Tool Data were collected using a pre-designed, pre-tested, structured questionnaire, prepared after an extensive review of the published literature and validated by subject experts for content and face validity, followed by a pilot test on 30 participants (not included in the final analysis) to refine wording and estimate reliability (Cronbach's alpha > 0.7 for the attitude domain). The questionnaire comprised four sections: (a) sociodemographic and clinical profile; (b) knowledge domain (multiple-choice and true/false items on recommended adult vaccines, schedule, indications and contraindications); (c) attitude domain (5-point Likert-scale statements); and (d) practice domain (vaccination history and reasons for non-vaccination). Data Collection Procedure After obtaining informed written consent, the questionnaire was administered in a self-administered format through a face-to-face interview in a language comfortable to the participant (English/Hindi). Confidentiality and anonymity of responses were assured. Scoring Each correct knowledge item was scored 1 and incorrect/'don't know' as 0; total knowledge scores were categorised as good (≥75%), moderate (50-74%) and poor (<50%) knowledge. Attitude statements were scored on a Likert scale of 1 to 5 and dichotomised into favourable and unfavourable attitude based on the median score. Practice was recorded as a binary outcome (vaccinated/not vaccinated for individual vaccines) and as an overall adequate/inadequate practice score. Ethical Considerations The study was conducted after obtaining approval from the Institutional Ethics Committee of Venkateshwara Institute of Medical Sciences, Gajraula, approval no. 0853B. The study was conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants, and data confidentiality was maintained throughout. Statistical Analysis Data were entered into Microsoft Excel and analysed using SPSS software (version 26.0). Categorical variables were expressed as frequencies and percentages, and continuous variables as mean ± standard deviation. Associations between sociodemographic variables and knowledge, attitude and practice scores were tested using the chi-square test (or Fisher's exact test where applicable), with a p-value <0.05 considered statistically significant.

A total of 400 participants completed the questionnaire (response rate 96%). The mean age of participants was 38.6 ± 12.4 years, with 54.5% females and 45.5% males. Table 1 summarises the sociodemographic characteristics of the study population. Characteristic Number (n=400) Percentage (%) Age group: 18-30 years 142 35.5 Age group: 31-45 years 128 32.0 Age group: 46-60 years 87 21.8 Age group: >60 years 43 10.7 Gender: Male 182 45.5 Gender: Female 218 54.5 Residence: Urban 246 61.5 Residence: Rural 154 38.5 Education: Graduate and above 218 54.5 Education: Below graduate 182 45.5 Presence of a chronic comorbidity 134 33.5 Knowledge: Overall, 38.5% (n=154) of participants had good knowledge, 41.0% (n=164) had moderate knowledge, and 20.5% (n=82) had poor knowledge regarding adult immunization. Awareness of individual vaccines was highest for tetanus toxoid (81.2%) and influenza (64.0%), followed by hepatitis B (57.3%) and booster (69.8%), and was lowest for pneumococcal vaccine (19.5%) and herpes zoster vaccine (11.7%). Only 34.3% of participants were aware that adult vaccination recommendations differ based on age, comorbidity, occupation or pregnancy status. Attitude A favourable attitude toward adult immunization was noted in 72.3% (n=289) of participants. Most participants (78.5%) agreed that adult vaccination is important for preventing serious illness, and 69.0% agreed that they would accept a vaccine if recommended by their treating physician. However, 41.2% expressed concern about the cost of adult vaccines, and 28.0% believed vaccines were 'mainly meant for children,' reflecting a persistent misconception. Practice Despite a largely favourable attitude, actual vaccine uptake was low. Only 29.8% (n=119) of participants had received any adult vaccine other than tetanus toxoid vaccination; 18.5% had received the influenza vaccine, 9.3% pneumococcal vaccine, and less than 5% had received herpes zoster or hepatitis B vaccination as adults. Table 2 summarises the association between selected variables and overall KAP scores. Variable Good Knowledge (%) Adequate Practice (%) p-value Education ≥ Graduate 51.4 38.5 <0.001 Education < Graduate 22.5 18.7 — Urban residence 45.9 35.0 0.012 Rural residence 27.3 21.4 — Presence of comorbidity 49.3 41.8 0.004 No comorbidity 33.5 24.2 — Prior physician counselling 63.0 55.7 <0.001 No prior counselling 29.1 17.9 — On multivariate analysis, higher education, urban residence, presence of a chronic comorbidity and prior counselling by a treating physician remained independently associated with both better knowledge and better practice scores (p<0.05 for all). The most commonly cited barriers to vaccination were lack of awareness (46.2%), cost (34.5%), absence of physician recommendation (28.0%), and doubts about vaccine necessity in adults (21.3%).

The present study demonstrates a clear knowledge-attitude-practice gap in adult immunization, with a broadly favourable attitude (72.3%) not translating into commensurate vaccine uptake (29.8%). This pattern of 'good attitude, poor practice' mirrors findings across Indian studies conducted in very different populations and settings. In a tri-service study among adults in Western India, poor knowledge and low uptake of adult vaccines were similarly attributed to cost, limited availability, and low perceived susceptibility to vaccine-preventable disease, with education level directly correlating with better awareness and uptake — an association also confirmed in the present study.8,9. Interestingly, the knowledge gaps identified here are not limited to the lay public but extend to healthcare professionals themselves. A study among postgraduate resident doctors in a Navi Mumbai tertiary hospital found that more than a quarter were unaware that an adult immunization schedule even exists, despite high awareness of the vaccine specifically. Similarly, a two-centre KAP study among 500 doctors and nurses in Kerala found that while the majority were at least partially aware of adult immunization guidelines, complete awareness and consistent recommendation practices lagged behind, with medical faculty and continuing education identified as the dominant influence on knowledge — consistent with the strong association between physician counselling and both knowledge and practice observed in the present study. This convergence of findings across lay populations and healthcare professionals suggests that the KAP gap in adult immunization in India is systemic rather than confined to any single group, and that physicians who are themselves inadequately informed are unlikely to actively recommend adult vaccination to their patients.10-11. Vaccine-specific findings in the present study — notably very low awareness of pneumococcal and herpes zoster vaccination — align with a survey among MBBS students in Western Uttar Pradesh, which similarly found striking gaps in awareness of cholera and herpes zoster vaccines despite reasonable awareness of hepatitis B vaccination, and with a nationwide survey of pediatricians regarding adult pneumococcal vaccination published in the Journal of the Association of Physicians of India, which found inconsistent knowledge of this vaccine even among practising specialists. Taken together, these findings suggest that awareness campaigns in India have so far been more successful for high-visibility vaccines such as tetanus toxoid than for less publicised but clinically important adult vaccines. The multicentre KAP study coordinated through AIIMS Rishikesh, which focused on healthcare professionals' knowledge and practice regarding vaccination of older adults, similarly concluded that despite international recommendations, routine vaccination of adults aged 60 years and above is not widely practised in India — a finding echoed in the present study by the low practice scores among the older age subgroup and the strong association between comorbidity status and both knowledge and practice. This underlines the importance of specifically targeting geriatric and comorbid populations, who stand to benefit most from adult immunization, in future awareness interventions. The persistence of vaccine hesitancy even among relatively well-informed groups deserves attention. A study from Delhi documented notable hesitancy for adult vaccines not only among the general public but also among doctors and their own family members, indicating that professional medical exposure alone does not eliminate hesitancy rooted in cost concerns, perceived low risk, or lack of a specific recommendation — themes that also emerged as leading barriers in the present study. Encouragingly, an exploratory survey among the general adult population in a tertiary care hospital in Hyderabad found that structured educational interventions could measurably improve subsequent vaccine uptake, suggesting that the KAP gap identified here is amenable to correction through targeted health education, opportunistic counselling during routine consultations, and reminder-recall systems, rather than reflecting fixed or unchangeable attitudes. Historically, KAP surveys have been a well-validated tool in the Indian immunization context; an early 30-cluster KAP survey on childhood immunization conducted in urban slums of Lucknow demonstrated that structured, community-based KAP assessment could reliably identify specific knowledge gaps and misconceptions to guide locally tailored immunization strategy.13 The present findings extend this same methodological approach to the comparatively under-studied domain of adult immunization, and reinforce the case made across the Indian literature for the development of a nationally endorsed, clearly communicated adult immunization schedule, backed by provider training and public awareness campaigns, in order to translate favourable attitudes into actual protective vaccine uptake. Limitations: This study is subject to the inherent limitations of a cross-sectional design, including recall bias in self-reported vaccination history and the inability to establish causal relationships. The findings, drawn from a single institution/setting, may have limited generalisability, and social desirability bias may have inflated reported attitude scores relative to actual belief.

1. Sashindran VK, Mohakuda SS, Murari T, Setlur R, Bansal V, et al. A Study on Knowledge Attitude and Practices of Adult Vaccination in Western India. J Vaccines Res Vaccin. 2018;6:011. 2. Kashyap et al. Knowledge, Attitude, and Practices Regarding Adult Immunization among Postgraduate Resident Doctors in MGM Hospital, Navi Mumbai, India. 2018. 3. Rahiman SA, et al. A study on knowledge, attitude and practices (KAP) towards adult immunizations among health care professionals. J Family Med Prim Care. 2018 Jan (Southern India, Malabar region, Kerala). 4. Multicentre, cross-sectional, questionnaire-based online study on knowledge, attitude and practice related to vaccination in older adults among healthcare professionals in India. Institutional Ethics Committee, All India Institute of Medical Sciences, Rishikesh. December 2017-January 2018. 5. Evaluation of Knowledge, Attitude and Practices Related to Adult Immunisation in a Medical Institution in Western Uttar Pradesh, India (cross-sectional study among 119 MBBS students). 6. Knowledge, attitudes and practices towards immunization among adult population in a tertiary care hospital – exploratory survey. Hyderabad, India, 2015-2016. 7. Development and Validation of a Questionnaire to Assess the Knowledge, Attitude, and Practices Regarding Adult Immunization amongst Resident Physicians at an Apex Tertiary Care Center in India. ScienceDirect 2018. 8. Knowledge, Attitude, and Practice of Adult Pneumococcal Vaccination in India: A Prospective, Cross-sectional, Questionnaire-based Survey of Pediatricians. J Assoc Physicians India. 2018;73(5) Suppl 1:15. 9. Bhola Nath, Singh JV, Awasthi S, Bhushan V, Kumar V, Singh SK. KAP Study on Immunization of Children in a City of North India – A 30 Cluster Survey. Online J Health Allied Sci. 2008;7(1). 10. Kalra N, Kalra T, Mishra S, Basu S, Bhatnagar N. Hesitancy for Adult Vaccines Among Healthcare Providers and their Family Members in Delhi, India: A Cross-Sectional Study. Dialogues Health. 2012;1:100044. 11. World Health Organization. SAGE Working Group on Vaccine Hesitancy: Report on Strategies for Addressing Vaccine Hesitancy. Geneva: WHO. 12. Advisory Committee on Immunization Practices (ACIP), Centers for Disease Control and Prevention. Recommended Adult Immunization Schedule, United States. Ann Intern Med (current annual edition). 13. Ministry of Health and Family Welfare, Government of India. Guidelines and policy documents on immunization, Universal Immunization Programme.