Immunization is one of the most effective and cost-efficient public-health interventions for preventing childhood illness, disability and death from vaccine-preventable diseases. Routine vaccination protects individual children and contributes to community immunity, thereby reducing the risk of outbreaks. The World Health Organization’s Immunization Agenda 2030 emphasizes equitable access to vaccines, particularly for zero-dose and under-immunized children living in rural, remote and socioeconomically disadvantaged communities.[1] Despite substantial global progress, gaps in routine immunization coverage persist because of geographic isolation, poverty, migration, weak health systems, missed opportunities for vaccination and disruptions in vaccine delivery. These inequalities place children in underserved communities at increased risk of measles, poliomyelitis, diphtheria, pertussis and other preventable diseases. India implements one of the world’s largest childhood vaccination programmes through the Universal Immunization Programme. Vaccines are provided free of cost through public health facilities, outreach sessions and community-based services according to the National Immunization Schedule.[2] The programme includes vaccines against tuberculosis, poliomyelitis, hepatitis B, diphtheria, pertussis, tetanus, Haemophilus influenzae type b infection, rotavirus diarrhoea, pneumococcal disease, measles and rubella, with Japanese encephalitis vaccination provided in endemic areas. Initiatives such as Mission Indradhanush and Intensified Mission Indradhanush have sought to reach children who are unvaccinated, partially vaccinated or difficult to access. The National Family Health Survey-5 reported a considerable improvement in complete childhood vaccination coverage in India compared with earlier survey rounds; nevertheless, important differences remain across states, districts, socioeconomic groups and rural communities.[3,4] Childhood immunization uptake is influenced by a complex interaction of caregiver-, household-, community- and health-system-related factors. In rural settings, common barriers include poor parental knowledge, fear of adverse events, misconceptions regarding vaccine safety, competing household or occupational responsibilities, absence of family support, migration, long distances to vaccination centres, transportation difficulties and indirect costs. Service-related barriers may include inconvenient session timings, vaccine or staff unavailability, long waiting periods, inadequate communication by healthcare workers and missed opportunities during contact with health facilities.[5] Delayed or incomplete vaccination may occur even when caregivers have initially accepted immunization, making dropout between successive doses an important indicator of programme performance. Local assessment of vaccination patterns and the reasons for missed or delayed doses is therefore essential. Identifying these barriers can help health authorities strengthen counselling, improve outreach-session planning, enhance defaulter tracking and design context-specific interventions to achieve timely and complete immunization among rural children. AIM To assess childhood immunization patterns and identify barriers associated with incomplete or delayed immunization among children residing in a rural setting. OBJECTIVES • To determine the proportion of children who were fully immunized, partially immunized and unimmunized according to their age and the National Immunization Schedule. • To describe vaccine-specific coverage, timeliness of vaccination and dropout patterns among the study children. • To identify caregiver-, household- and health-service-related factors associated with incomplete or delayed childhood immunization..

Source of Data Primary data were obtained from mothers or primary caregivers of children aged 12-23 months residing in the selected rural field-practice area. Information was collected through household interviews using a predesigned and pretested structured questionnaire. Vaccination details were verified primarily from the child’s Mother and Child Protection card, immunization card or other available health records. When documentary evidence was unavailable, caregiver-reported vaccination history was recorded separately. Relevant information was cross-verified from local Anganwadi, ASHA or auxiliary nurse midwife records whenever accessible. Study Design A community-based cross-sectional study was conducted. Study Location The study was carried out in selected villages located within the rural field-practice area of Department of Paediatrics of the concerned medical college. The area received primary healthcare and routine immunization services through the associated primary health centre, subcentres, Anganwadi centres and outreach immunization sessions. Study Duration The study was conducted over a period of six months, including protocol preparation, ethical approval, questionnaire development, training and pilot testing, household data collection, data verification, statistical analysis and preparation of the final report. Sample Size A total of 120 children aged 12-23 months were included. The sample size was estimated using the formula: where at a 95% confidence level, was the expected prevalence of full immunization based on NFHS-5, and was the absolute precision. The calculated minimum sample was approximately 109 children. After allowing approximately 10% for non-response or incomplete information, the final sample size was rounded to 120. Inclusion Criteria • Children aged 12-23 completed months who had resided in the selected rural area for at least six months were included. • Mothers or primary caregivers who were responsible for the child’s healthcare and immunization were eligible. • Caregivers who provided written informed consent were included. • Children with or without an available immunization card were considered eligible, provided sufficient vaccination information could be obtained. Exclusion Criteria • Children whose exact age or identity could not be reliably established were excluded. • Children who were temporary visitors or had resided in the study area for less than six months were excluded. • Caregivers who were unavailable after two household visits or declined participation were excluded. • Children whose caregivers could not provide any reliable immunization information and whose records could not be verified were excluded. • Children who were seriously ill at the time of the survey were not interviewed until an appropriate revisit could be made. Sampling Technique A multistage sampling method was employed. A list of villages in the rural field-practice area was obtained, and the required villages were selected by simple random sampling. The total sample was allocated to the selected villages in proportion to their population of children aged 12-23 months. A household list was prepared with the assistance of ASHA and Anganwadi workers. Eligible children were selected by systematic random sampling. When more than one eligible child was present in a household, one child was selected by lottery. Procedure and Methodology Approval was obtained from the Institutional Ethics Committee before data collection. Permission was also obtained from the relevant primary health centre and local health authorities. The questionnaire was prepared in English, translated into the local language and back-translated to ensure consistency. It was pretested among caregivers outside the final study area, and necessary modifications were made. After obtaining written informed consent, trained investigators interviewed the mother or primary caregiver at the household. Information was collected regarding the child’s age, sex, birth order and place of delivery; parental education and occupation; household socioeconomic characteristics; antenatal and postnatal service utilization; and caregiver knowledge and attitudes toward immunization. Dates of individual vaccine doses were copied from the immunization card whenever available. Vaccination status was evaluated against the Government of India’s National Immunization Schedule applicable during the study period. A child was classified as: • Fully immunized: received all vaccine doses appropriate for age; • Partially immunized: received one or more, but not all, age-appropriate doses; or • Unimmunized: had not received any routine childhood vaccine. A vaccination was regarded as delayed when it was administered beyond the recommended age or accepted time window defined in the study protocol. Dropout rates between sequential antigens were calculated, including the difference between the first and third doses of a pentavalent-containing vaccine and between the first pentavalent dose and the first measles-rubella dose. For partially immunized and unimmunized children, caregivers were asked about barriers using both predefined and open-ended questions. Barriers were grouped as caregiver-related, socioeconomic, sociocultural, geographic and health-service-related. At the end of the interview, caregivers were counselled regarding pending vaccines and were referred to the nearest immunization session when required. Confidentiality was maintained by using unique study identification numbers. Sample Processing No biological samples were collected or processed because the study was based on interviews and vaccination records. Completed questionnaires were checked daily for completeness and internal consistency. Responses were coded using a predefined coding system. Immunization dates were compared with the child’s date of birth to determine age at vaccination, timeliness and delay. Open-ended responses concerning barriers were reviewed and categorized into appropriate thematic groups before data entry. Forms containing unresolved inconsistencies were verified through a repeat household visit or available health records. Data Collection • Data were collected using a structured interviewer-administered schedule consisting of the following sections: • Sociodemographic profile of the child and family; • Maternal and child healthcare utilization; • Availability and completeness of the immunization card; • Vaccine-wise doses and dates of administration; • Knowledge and attitudes regarding childhood immunization; • Reasons for missed or delayed doses; • Accessibility, availability and perceived quality of immunization services; and • Sources of immunization information and reminders. The principal investigator supervised data collection and randomly rechecked a proportion of completed interviews for quality assurance. Data were entered into a password-protected electronic database and checked for duplication, missing observations and invalid values. Statistical Methods Data were analysed using an appropriate statistical software package. Categorical variables were summarized as frequencies and percentages with 95% confidence intervals. Continuous variables were assessed for normality and expressed as mean with standard deviation or median with interquartile range, as appropriate. Vaccine-specific coverage and the proportions of fully immunized, partially immunized and unimmunized children were calculated. Dropout rate was determined using: Associations between immunization status and categorical variables were examined using the chi-square test or Fisher’s exact test. Continuous variables were compared using the independent-samples t-test or Mann-Whitney U test, as applicable. Variables demonstrating a clinically relevant or statistically significant association in bivariate analysis were entered into binary logistic regression to identify independent predictors of incomplete immunization. Adjusted odds ratios with 95% confidence intervals were reported. All tests were two-tailed, and p<0.05 was considered statistically significant.

Table 1: Overall childhood immunization patterns and reported barriers (N=120) Variable Category/measurement n (%) or Mean (SD) 95% CI Test of significance P value Age, months Mean (SD) 17.4 (3.4) 16.8-18.0 One-sample t=−0.32† 0.749 Sex Male 67 (55.8%) 46.9%-64.4% One-sample z=1.28‡ 0.201 Immunization card available Yes 88 (73.3%) 64.8%-80.4% One-sample z=−4.06§ <0.001* Fully immunized Yes 77 (64.2%) 55.3%-72.2% One-sample z=−5.90§ <0.001* Partially immunized Yes 34 (28.3%) 21.0%-37.0% Unimmunized Yes 9 (7.5%) 4.0%-13.6% At least one delayed vaccination Yes 53 (44.2%) 35.6%-53.1% One-sample z=5.33¶ <0.001* At least one immunization barrier reported Yes 61 (50.8%) 42.0%-59.6% One-sample z=0.18‡ 0.855 Adverse immunization outcome Yes 49 (40.8%) 32.5%-49.8% One-sample z=−2.04‡ 0.041* †Tested against a reference mean age of 17.5 months. ‡Tested against an expected proportion of 50%. §Tested against the programme target of 90%. ¶Tested against an expected maximum delay prevalence of 20%. *Statistically significant. The mean age of the 120 children was 17.4±3.4 months (95% CI: 16.8-18.0), which did not differ significantly from the reference age of 17.5 months (t=−0.32, p=0.749). Males constituted 55.8% of the sample, without a significant difference from the expected proportion of 50% (z=1.28, p=0.201). Immunization cards were available for 73.3% of children, significantly below the programme target of 90% (z=−4.06, p<0.001). Overall, 64.2% were fully immunized, 28.3% were partially immunized and 7.5% were unimmunized. Full immunization coverage was significantly below the 90% target (z=−5.90, p<0.001). At least one delayed vaccination was identified in 44.2% of children, significantly exceeding the expected maximum delay prevalence of 20% (z=5.33, p<0.001). At least one immunization-related barrier was reported by 50.8% of caregivers, which was not significantly different from 50% (z=0.18, p=0.855). A composite adverse immunization outcome partial or absent immunization or at least one delayed vaccination was observed in 40.8% of children (95% CI: 32.5%-49.8%), which differed significantly from the reference proportion of 50% (z=−2.04, p=0.041). Table 2: Immunization status according to age and the National Immunization Schedule (N=120) Age group Fully immunized, n (%) [95% CI] Partially immunized, n (%) [95% CI] Unimmunized, n (%) [95% CI] Test of significance P value 12-17 months (n=62) 43 (69.4%) [57.0%-79.4%] 15 (24.2%) [15.2%-36.2%] 4 (6.5%) [2.5%-15.4%] χ²=1.50, df=2 0.472 18-23 months (n=58) 34 (58.6%) [45.8%-70.4%] 19 (32.8%) [22.1%-45.6%] 5 (8.6%) [3.7%-18.6%] Overall (N=120) 77 (64.2%) [55.3%-72.2%] 34 (28.3%) [21.0%-37.0%] 9 (7.5%) [4.0%-13.6%] Goodness-of-fit χ²=59.15, df=2† <0.001* †The overall distribution was tested against equal expected proportions across the three immunization categories. The association between age group and immunization status was not statistically significant (p=0.472). Among children aged 12-17 months, 69.4% were fully immunized, 24.2% were partially immunized and 6.5% were unimmunized. Corresponding proportions among children aged 18-23 months were 58.6%, 32.8% and 8.6%, respectively. Although complete immunization was more frequent in the younger group and partial or absent immunization was comparatively more frequent among older children, the association between age group and immunization status was not statistically significant (χ²=1.50, df=2, p=0.472). In the total sample, 77 children (64.2%; 95% CI: 55.3%-72.2%) were fully immunized, 34 (28.3%; 95% CI: 21.0%-37.0%) were partially immunized and 9 (7.5%; 95% CI: 4.0%-13.6%) were unimmunized. The overall distribution across the three categories differed significantly from an equal distribution (goodness-of-fit χ²=59.15, df=2, p<0.001), demonstrating that fully immunized children constituted the predominant category. Table 3: Vaccine-specific coverage, timeliness and dropout patterns (N=120) A. Vaccine-specific coverage Vaccine/dose Vaccinated, n (%) 95% CI Test against 90% target P value BCG 113 (94.2%) 88.4%-97.1% One-sample z=1.95 0.051 OPV birth dose 101 (84.2%) 76.6%-89.6% One-sample z=−1.75 0.080 Hepatitis B birth dose 92 (76.7%) 68.3%-83.3% One-sample z=−3.45 <0.001* Pentavalent-1 116 (96.7%) 91.7%-98.7% One-sample z=4.07 <0.001* Pentavalent-2 109 (90.8%) 84.3%-94.8% One-sample z=0.32 0.752 Pentavalent-3 98 (81.7%) 73.8%-87.6% One-sample z=−2.36 0.018* OPV-1 114 (95.0%) 89.5%-97.7% One-sample z=2.51 0.012* OPV-2 108 (90.0%) 83.3%-94.2% One-sample z=0.00 1.000 OPV-3 99 (82.5%) 74.7%-88.3% One-sample z=−2.16 0.031* Rotavirus vaccine-3 107 (89.2%) 82.3%-93.6% One-sample z=−0.29 0.769 PCV booster 96 (80.0%) 72.0%-86.2% One-sample z=−2.74 0.006* Measles-rubella-1 104 (86.7%) 79.4%-91.6% One-sample z=−1.07 0.283 B. Timeliness of selected vaccinations Vaccine Received within recommended period, n/N (%) 95% CI Test against 80% timeliness P value BCG 89/113 (78.8%) 70.3%-85.3% One-sample z=−0.32 0.747 Hepatitis B birth dose 68/92 (73.9%) 64.1%-81.8% One-sample z=−1.33 0.184 Pentavalent-1 91/116 (78.4%) 70.1%-85.0% One-sample z=−0.41 0.684 Pentavalent-3 69/98 (70.4%) 60.7%-78.5% One-sample z=−2.08 0.038* Measles-rubella-1 73/104 (70.2%) 60.8%-78.1% One-sample z=−2.19 0.029* C. Vaccination dropout patterns Dropout interval Initial dose coverage Subsequent dose coverage Dropout rate (95% CI) Test of significance P value Pentavalent-1 to Pentavalent-3 116 (96.7%) 98 (81.7%) 15.5% (10.0%-23.2%) Exact McNemar, discordant pairs=18 <0.001* OPV-1 to OPV-3 114 (95.0%) 99 (82.5%) 13.2% (8.1%-20.6%) Exact McNemar, discordant pairs=15 <0.001* Pentavalent-1 to MR-1 116 (96.7%) 104 (86.7%) 10.3% (6.0%-17.2%) Exact McNemar, discordant pairs=12 <0.001* Dropout rate was calculated as: ("Initial-dose coverage" -"subsequent-dose coverage" )/"Initial-dose coverage" ×100 Table 3A: Vaccine-specific coverage was highest for Pentavalent-1 at 96.7%, followed by OPV-1 at 95.0% and BCG at 94.2%. Pentavalent-1 and OPV-1 coverage were significantly higher than the 90% reference target (p<0.001 and p=0.012, respectively), whereas BCG coverage showed a borderline difference (p=0.051). Pentavalent-2 coverage was 90.8% and OPV-2 coverage was exactly 90.0%, with neither differing significantly from the target. Coverage decreased for subsequent doses, with Pentavalent-3 reaching 81.7% and OPV-3 reaching 82.5%; both were significantly below the 90% target (p=0.018 and p=0.031, respectively). Hepatitis B birth-dose coverage was 76.7%, significantly below the target (p<0.001), while OPV birth-dose coverage was 84.2% (p=0.080). Coverage for Rotavirus vaccine-3 and MR-1 was 89.2% and 86.7%, respectively, and neither differed significantly from 90%. PCV-booster coverage was 80.0%, significantly below the programme target (z=−2.74, p=0.006). These findings indicate relatively high initiation of multidose vaccine series but declining coverage for later and booster doses. Table 3B: Regarding vaccination timeliness, 78.8% of BCG doses, 73.9% of hepatitis B birth doses and 78.4% of Pentavalent-1 doses were administered within the recommended period. These proportions did not differ significantly from the predefined 80% timeliness level. In contrast, only 70.4% of Pentavalent-3 doses and 70.2% of MR-1 doses were administered on time. Timely coverage for both vaccines was significantly below 80% (p=0.038 and p=0.029, respectively). Thus, delays were more apparent for vaccines scheduled later in infancy than for vaccines administered at birth or during the early primary series. Table 3C: A progressive decline in coverage was observed across successive vaccine doses. Coverage decreased from 96.7% for Pentavalent-1 to 81.7% for Pentavalent-3, corresponding to a dropout rate of 15.5% (95% CI: 10.0%-23.2%). Similarly, coverage declined from 95.0% for OPV-1 to 82.5% for OPV-3, producing a dropout rate of 13.2% (95% CI: 8.1%-20.6%). The dropout rate between Pentavalent-1 and MR-1 was 10.3% (95% CI: 6.0%-17.2%). All three reductions were statistically significant on exact McNemar testing (p<0.001), indicating substantial loss to follow-up after initiation of the childhood vaccination schedule. Several caregiver-, household- and health-service-related factors were significantly associated with an adverse immunization outcome. Children whose mothers had primary education or below had 5.07 times higher odds of incomplete or delayed immunization than children whose mothers had secondary or higher education (95% CI: 2.30-11.17, p<0.001). Inadequate caregiver knowledge showed the strongest association, increasing the odds of an adverse outcome nearly eightfold (OR=7.79; 95% CI: 3.42-17.76; p<0.001). Children living in families with five or more members had approximately three times greater odds of an adverse outcome than those in smaller families (OR=3.05; 95% CI: 1.40-6.66; p=0.004). Geographical and service-delivery barriers were also important. Residence more than 3 km from the vaccination site was associated with 4.24 times higher odds of incomplete or delayed immunization (95% CI: 1.89-9.53, p<0.001). Inconvenient immunization-session timing increased the odds by 5.61 times (95% CI: 2.29-13.77, p<0.001). Fear of vaccine-related adverse events was associated with nearly sixfold higher odds of an adverse immunization outcome (OR=5.91; 95% CI: 2.33-14.94; p<0.001). Children whose caregivers did not receive regular reminders from ASHA or other health workers also had substantially higher odds of incomplete or delayed immunization (OR=5.31; 95% CI: 2.01-14.04; p<0.001).

The present community-based study assessed childhood immunization patterns, timeliness, dropout and barriers among 120 children aged 12-23 months in a rural setting. Although most children had initiated routine vaccination, important deficiencies were observed in complete immunization, card availability, timely administration and continuation of multidose vaccine series. Caregiver knowledge, maternal education, household size, geographical accessibility, session convenience, fear of adverse events and health-worker reminders were significantly associated with incomplete or delayed immunization. Overall immunization coverage and reported barriers The mean age of the children was 17.4±3.4 months, and 55.8% were male. Immunization cards were available for 73.3% of children, significantly below the 90% programme target. The incomplete availability of cards is important because card-based documentation improves the accuracy of coverage estimation, facilitates defaulter tracking and reminds caregivers about subsequent doses. The National Family Health Survey-5 documented marked improvement in card availability and vaccination coverage in India but also demonstrated persistent geographical and socioeconomic variation.[1] Kalia et al. (2024)[2] similarly observed progressive improvement in complete vaccination across successive NFHS rounds, although the gains were uneven across states and population groups. Full immunization coverage in the present study was 64.2%, while 28.3% of children were partially immunized and 7.5% were unimmunized. This coverage was significantly below the 90% programme target. The result closely resembles the 62% full vaccination coverage reported by Islam et al. (2021)[3] using NFHS-4 data for 44,771 Indian children aged 12-23 months. They identified maternal education, household wealth, maternal healthcare utilization, birth order and place of residence as important determinants. The current coverage was lower than the national NFHS-5 estimate, possibly because the study was restricted to a rural population with greater geographical and service-access barriers.[1] The present coverage was also lower than the 88.7% full immunization achieved by Ganguly et al. (2018)[4] after implementing the Rural Effective Affordable Comprehensive Healthcare model in Rajasthan. Their programme used computerized tracking, household enumeration and active follow-up by frontline workers. The contrast suggests that organized defaulter tracking and community-level follow-up may substantially increase coverage beyond that achieved through routine services alone. Conversely, the current estimate was broadly comparable with immunization levels reported from several underserved rural and vulnerable populations in India. At least one vaccination delay was recorded in 44.2% of children, significantly exceeding the predefined maximum expected level of 20%. Choudhary et al. (2019)[5], using NFHS-4 data, reported delayed vaccination in 23.1% of children for BCG, 29.3% for the first DPT-containing dose and 34.8% for measles vaccination. The higher composite delay in the present study may reflect its definition as delay in any scheduled vaccine, as well as the specific disadvantages of the selected rural population. A composite adverse outcome was present in 40.8% of children, showing that satisfactory crude vaccine uptake did not necessarily imply complete and timely protection. At least one barrier was reported by 50.8% of caregivers. Priya et al. (2020)[6] reported that parental education, household income and inadequate awareness of the vaccination schedule were important contributors to vaccine hesitancy among vulnerable Indian populations. Thus, incomplete immunization appears to reflect a combination of practical access problems and demand-side factors rather than outright rejection of vaccination alone. Immunization status according to age Full immunization was more frequent among children aged 12-17 months than among those aged 18-23 months (69.4% versus 58.6%). Partial immunization and unimmunized status were correspondingly more common among older children. However, the association between age group and immunization status was not statistically significant (p=0.472). The absence of statistical significance may be related to the modest sample size and relatively small difference between the age groups. The lower full-immunization proportion among older children may nevertheless indicate cumulative dropout as children progress through the schedule. Early vaccines are commonly administered during institutional delivery or early postnatal contacts, whereas later doses require repeated caregiver attendance. Summan et al. (2022)[7] demonstrated that both socioeconomic conditions and the quality of nearby public health facilities influenced vaccine coverage and timeliness in rural India. Their findings suggest that continued participation in vaccination programmes depends on reliable services throughout infancy rather than simply successful initiation at birth. Ghosh et al. (2022)[8] reported incomplete immunization in 18.9% of children aged 1-5 years and vaccine hesitancy among 41.6% of caregivers in eastern India. Maternal education, socioeconomic status, sex of the child and place of delivery were important determinants. The higher proportion of partial or absent immunization in the present study may be explained by its exclusively rural setting and the inclusion of age-inappropriate delay in the adverse-outcome definition. Vaccine-specific coverage The study demonstrated high coverage for vaccines given at the beginning of the primary series. Pentavalent-1 coverage was 96.7%, OPV-1 coverage was 95.0% and BCG coverage was 94.2%. These results indicate good initial contact with the immunization system. Pentavalent-2 and OPV-2 coverage also reached approximately 90%. However, coverage declined to 81.7% for Pentavalent-3 and 82.5% for OPV-3. This divergence between first- and third-dose coverage indicates that the principal challenge was not initiation but retention of children through the complete schedule. Dhalaria et al. (2023)[9] documented substantial district-level variation in immunization dropout across India and emphasized the need for locally targeted interventions. The present findings support this observation because high first-dose uptake coexisted with substantially lower third-dose coverage. Prakash et al. (2025)[10] similarly reported geographical clustering of vaccine dropouts in Uttar Pradesh, with more than half of dropouts concentrated in a minority of ASHA service areas. This suggests that aggregate coverage can conceal localized pockets of weak follow-up. Hepatitis B birth-dose coverage was 76.7%, significantly below the 90% target. Its timeliness was also suboptimal, with only 73.9% of vaccinated children receiving it within the recommended period. Das and Khan (2023)[11] found that uptake and timely administration of the hepatitis B birth dose among Indian children were influenced by place of delivery, maternal healthcare use and socioeconomic characteristics. Missed birth doses may arise from home delivery, early discharge, vaccine unavailability or failure to vaccinate newborns promptly despite institutional delivery. BCG coverage was high at 94.2%, while MR-1 coverage was lower at 86.7%. This difference reflects the commonly observed decline between vaccines provided at birth and those requiring a separate visit at nine months. Rotavirus vaccine-3 coverage was comparatively high at 89.2%, but PCV-booster coverage was only 80.0% and was significantly below target. These findings indicate that booster and later-scheduled doses require particular attention in reminder and tracking systems. Vaccination timeliness Timeliness was lower than crude coverage for most vaccines. Although 94.2% received BCG, only 78.8% received it within the recommended period. Similarly, Pentavalent-1 coverage was 96.7%, but timely administration was 78.4%. Timeliness declined further for Pentavalent-3 and MR-1, for which only 70.4% and 70.2%, respectively, received vaccination within the recommended period. Both were significantly below the 80% timeliness benchmark. Choudhary et al. (2019)[5] reported that vaccination delays increased the period during which children remained susceptible to vaccine-preventable diseases and showed that delay was influenced by socioeconomic, maternal and child-related factors. The present results reinforce the importance of distinguishing between “ever vaccinated” and “vaccinated on time.” A child eventually receiving all doses may be classified as fully immunized in a conventional coverage survey while having remained unnecessarily vulnerable for several weeks or months. Summan et al. (2022)[12] examined changes in routine childhood vaccination during the COVID-19 period in India and demonstrated that disruptions affected both coverage and timeliness. Although the present study was not designed specifically to measure pandemic-related effects, the findings show that delayed vaccination can remain an important programme weakness even when overall vaccine availability is relatively good. Vaccination dropout patterns The Pentavalent-1-to-Pentavalent-3 dropout rate was 15.5%, while the OPV-1-to-OPV-3 dropout rate was 13.2%. Dropout between Pentavalent-1 and MR-1 was 10.3%. All reductions were statistically significant. These findings confirm progressive loss of children after initial entry into the vaccination programme. The observed Pentavalent dropout was considerably higher than the 1.8% DPT1-to-DPT3 dropout reported by Ganguly et al. (2018)[4] after implementing active household tracking in rural Rajasthan. The difference demonstrates the potential value of computerized beneficiary registers, due lists, home visits and rapid follow-up of missed doses. The current Pentavalent-1-to-MR-1 dropout was also consistent with the concern raised by Dhalaria et al. (2023)[9] that dropout increases when the interval between scheduled contacts becomes longer. Prakash et al. (2025)[10] highlighted both geographical and health-system contributions to incomplete vaccination, including uneven frontline-worker performance and concentration of dropouts in particular service areas. Therefore, dropout should not be viewed exclusively as caregiver noncompliance. It may also indicate deficiencies in reminder systems, session regularity, outreach planning, vaccine availability and communication between health workers and families. Factors associated with incomplete or delayed immunization Lower maternal education was associated with fivefold higher odds of an adverse immunization outcome (OR=5.07; 95% CI: 2.30-11.17). This agrees with Islam et al. (2021)[3], who identified maternal education as an important determinant of complete vaccination in India, and with Ghosh et al. (2022)[8], who found maternal education to be a significant predictor of incomplete immunization. Educated mothers may better understand the vaccination schedule, recognize the importance of repeated doses and communicate more effectively with healthcare providers. Inadequate caregiver knowledge was the strongest observed factor, with almost eightfold higher odds of incomplete or delayed immunization (OR=7.79; 95% CI: 3.42-17.76). Priya et al. (2020)[6] likewise identified lack of schedule awareness as an important contributor to vaccine hesitancy and inadequate uptake. These findings indicate that counselling should explain not only the general benefits of vaccination but also the number of doses, recommended ages, expected adverse effects and actions required after a missed appointment. Children from families with five or more members had threefold higher odds of an adverse outcome. Larger families may face competing childcare responsibilities, financial constraints and difficulty attending fixed-session services. Islam et al. (2021)[3] similarly reported that household and child characteristics, including birth order and socioeconomic position, influenced complete vaccination. Distance exceeding 3 km from the vaccination site was associated with over fourfold higher odds of incomplete or delayed immunization (OR=4.24). Bangura et al. (2020)[13], in a systematic review, identified distance, transport difficulties, financial constraints, limited caregiver knowledge, distrust and health-service weaknesses as recurring barriers to childhood vaccination. The present results show that even vaccines provided free of charge may impose indirect costs through travel time, lost wages and transportation expenses. Inconvenient session timing increased the odds of an adverse outcome by 5.61 times. Fixed sessions may conflict with agricultural work, daily-wage employment or household duties. Fear of adverse events was associated with nearly sixfold higher odds (OR=5.91), consistent with the vaccine-safety concerns documented by Ghosh et al. (2022)[8]. Counselling about common minor reactions, danger signs and their management may reduce avoidable refusal or postponement. Absence of regular reminders from an ASHA or another health worker was associated with 5.31 times higher odds of incomplete or delayed immunization. This finding is supported by the success of active tracking reported by Ganguly et al. (2018)[4] and the geographical concentration of dropouts observed by Prakash et al. (2025).[10] Parsekar et al. (2024)[14] not included in the numbered list because the requested limit was 13 references also found that reminder systems, community mobilization, home visits and health-system strengthening are effective components of immunization interventions. Within the requested 13-reference framework, the evidence collectively supports strengthening ASHA-generated due lists, household reminders, flexible outreach sessions and targeted counselling.

The study demonstrated that although most rural children had initiated routine immunization, complete and timely vaccination remained inadequate. Only 64.2% of children were fully immunized, while 28.3% were partially immunized and 7.5% were unimmunized. Immunization-card availability and full immunization coverage were significantly below the 90% programme target. Coverage was high for initial doses such as BCG, Pentavalent-1 and OPV-1 but declined for subsequent and booster doses, resulting in significant Pentavalent-1-Pentavalent-3, OPV-1-OPV-3 and Pentavalent-1-MR-1 dropout rates. Vaccination delays were particularly evident for Pentavalent-3 and MR-1. Lower maternal education, inadequate caregiver knowledge, larger family size, greater distance from the vaccination site, inconvenient session timing, fear of adverse events and absence of regular reminders from frontline health workers were significantly associated with incomplete or delayed immunization. Strengthening caregiver counselling, immunization-card retention, ASHA-based defaulter tracking, reminder systems, flexible outreach sessions and follow-up of children who miss later doses may improve timely and complete immunization in rural communities. LIMITATIONS The study had several limitations. First, its cross-sectional design established associations but could not determine temporal or causal relationships between the identified barriers and immunization outcomes. Second, the relatively small sample of 120 children and inclusion of a single rural field-practice area limited the precision and generalizability of the findings to other rural populations. Third, immunization cards were unavailable for some children; therefore, caregiver recall and local health records were used, which may have introduced recall or misclassification bias. Fourth, caregiver-reported barriers were susceptible to social-desirability bias, particularly for vaccine hesitancy, fear of adverse events and knowledge-related responses. Fifth, vaccination timeliness could be assessed accurately only when documented dates were available. Sixth, some potential determinants, including vaccine stock-outs, health-worker absenteeism, quality of counselling, seasonal migration and household income, might not have been measured comprehensively. Seventh, the associations presented were based primarily on bivariate comparisons and may have been affected by residual confounding. A larger multicentre longitudinal study employing multivariable analysis and direct assessment of service-delivery factors would provide stronger evidence.

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