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Demography and determinants of incomplete immunization in children aged 1–5 years and vaccine-hesitancy among caregivers: An Eastern Indian perspective

Open AccessPublished:September 29, 2022DOI:https://doi.org/10.1016/j.cegh.2022.101155

      Abstract

      Background

      World Health Organization (WHO) declared vaccine-hesitancy (VH) as an emerging threat to global health. There are limited studies from developing countries, especially from Eastern India, addressing parental VH's determinants and its impact on childhood immunization. Current study aims to assess the prevalence of incomplete immunization in children and parental VH, explore the socio-demographic determinants, and delineate their interconnections.

      Material and methods

      In this hospital-based, cross-sectional study vaccination cards or parents’ recall method were used to inquire about immunization status and the Likert-vaccine hesitancy scale (VHS) developed by WHO Strategic Advisory Group Experts on Immunization (SAGE) was utilized as an instrument to measure VH. Multivariate analyses were performed to identify the independent predictors.

      Results

      The prevalence of incomplete immunization and VH were 18.9% and 41.6% respectively. Significant predictors of incomplete immunization were maternal education, socioeconomic status, gender, and place of delivery. Most responders believed vaccines are effective (99%), important for child's health (98%) and most vaccines offered by the government are beneficial (95%) but were also concerned about serious adverse effects (41%) and feared about new vaccines carrying more risk than old vaccines (16%). Maternal education and family type were significant determinants of VH. Incomplete immunization was significantly prevalent among children with vaccine-hesitant caregivers, though it was not found to be an independent predictor in multivariate analysis.

      Conclusions

      This study emphasizes the magnitude of the issue of incomplete immunization, VH, and unravels its contributing factors which will help public-health care providers with a roadmap to prioritize resources and focus on preventable measures like health education, ensuring institutional births, and free health-service delivery expansion to increase immunization coverage. Caregivers’ VH is a major roadblock to attaining better immunization coverage which can be tackled through proper counselling to improve their health literacy.

      Keywords

      Abbreviations:

      AEFI (Adverse Events Following Immunization), SAGE (Strategy Advisory Group of Experts), UIP (Universal Immunization Programme), VH (Vaccine Hesitancy), VHPs (Vaccine Hesitant Parents), VHS (Vaccine Hesitancy Scale), VPDs (Vaccine Preventable Diseases), WHO (World Health Organization)

      1. Introduction

      Immunization is a cost-effective way to impede vaccine-preventable diseases (VPDs) thereby reducing infant and childhood mortality globally.
      World Health Organisation (WHO)
      Protecting people from vaccine-preventable diseases.
      Universal Immunization Programme (UIP) was launched by the government of India in 1985 and continues to provide free vaccines against VPDs.
      Ministry of Health and Family Welfare, Government of India
      National Immunization Schedule for Infants.
      ,
      • Paul S.
      • Sahoo J.
      Four new vaccines for routine immunization in India: what about haemophilus influenza B and pneumococcal vaccine?.
      Unfortunately, despite the completion of three decades, only 76.4% of children aged 12–23 months received the complete schedule of UIP vaccines, and outbreaks of VPDs continue to occur in incompletely immunized sub-populations.

      International Institute for Population Sciences (IIPS) and ICF. National Family Health Survey (NFHS-5), 2019-20: India. Mumbai: International Institute for Population Sciences. Available from: http://rchiips.org/nfhs/index.shtml. [Assessed on, 10 27, 2021].

      Several complex challenges like social, economic, cultural, educational, psychological, and behavioural factors including parental hesitancy exist within communities alongside health care facility-related variables like-coverage of the health network, the existence and quality of outreach services, the quality of the cold chain, the liaison of communities with health services, the existence of population movements, and several other factors that are related to the vaccines in use, are also responsible for sub-optimal vaccine uptake.
      • Srivastava S.
      • Fledderjohann J.
      • Upadhyay A.K.
      Explaining socioeconomic inequalities in immunisation coverage in India: new insights from the fourth National Family Health Survey (2015-16).
      It is, therefore, essential to identify and monitor the contributing factors for incomplete immunization regularly at local levels, to develop appropriate strategies to tackle them in susceptible populations.
      Vaccine hesitancy (VH) is an emerging risk factor for incomplete immunization
      • Lane S.
      • MacDonald N.E.
      • Marti M.
      • Dumolard L.
      Vaccine hesitancy around the globe: analysis of three years of WHO/UNICEF joint reporting form data-2015–2017.
      and is perceived as one of the significant threats to Global Health.
      • World Health Organization
      It has been defined by World Health Organization (WHO) as a delay in acceptance or refusal of vaccines despite the availability of vaccine services and threatens to reverse the progress made in tackling VPDs. VH is complex and context-specific, varying across time, place, and vaccines. It is influenced by factors such as complacency, convenience, and confidence.
      • World Health Organization
      It occurs along a continuum of full acceptance to outright refusal of some or all of the vaccines.
      Most of the VH-related research has been conducted in developed countries. Researchers from developing countries have examined the attitudes towards vaccines and their relationship with vaccine uptakes. Studies utilizing standard tools to understand the prevalence of factors related to VH and its impact on childhood immunization are limited. Considering these scarcities, the current study aimed to assess the prevalence of incomplete immunization in children and vaccine hesitancy among their caregivers, explore its socio-demographic determinants, and delineate the interconnections between vaccine hesitancy and immunization status.

      2. Materials and methods

      2.1 Study design, settings, and population

      An institutional-based cross-sectional observational study was carried out in a tertiary care teaching institute from June 2018 to November 2019. This is the only referral hospital in the district and adjoining blocks, serving a huge population from rural areas and nearby cities. Children who were admitted with acute illness requiring inpatient care and attended paediatric outpatient department for minor illnesses or follow-up during the study period, aged 1–5 years, and did not have any contraindication to routine vaccination were enrolled for this study.

      2.2 Sample size determination and sampling technique

      The sample size (N) was estimated through Epi-Info version-7, with the formula, N = Z2pq ÷ e2. Where ‘Z’ is 1.96 for a 95% confidence interval (CI), ‘p’ is the prevalence, ‘q’ is (1-p) and ‘e’ is the relative precision (10% of p). For assessment of vaccination coverage among children and VH among their caregivers, ‘p’ was considered 15.6%
      International Institute for Population Sciences (IIPS) and ICF
      National family health survey (NFHS-4), India, 2015-16: West Bengal.
      and 28.9%
      • Cherian V.
      • Saini N.K.
      • Sharma A.K.
      • Philip J.
      Prevalence and predictors of vaccine hesitancy in an urbanized agglomeration of New Delhi, India [published online ahead of print, 2021 Feb 17].
      and, the estimated sample size was 2078 and 931 respectively. To make it round-off, we included a total of 2100 children of age 1–5 years. By systematic random sampling, every 5th child was selected till the required sample size was met and the 1st sample was selected by simple random technique.

      2.3 Development and validation of questionnaires

      A predesigned, pretested, semi-structured questionnaire was used to assess socio-demographic status. The immunization status was determined by vaccination card and if not available, a recall method was used. Likert vaccine hesitancy scale (VHS) questionnaire developed by WHO Strategic Advisory Group Experts on Immunization (SAGE)
      • World Health Organization
      group was used to assess VH among the caregivers.
      Questionnaires were first developed in English, then translated into Bengali by two different groups of experts independently (first group consists of medical personnel who are experts in the subject matter and the second group consists of non-medical personnel who are experts in language use). Next, these two different sets of Bengali version questionnaires were back-translated into English by another two different groups of experts independently, who were totally unaware of the content of the original English version. Then, an open discussion between these four groups of experts was held to consolidate all four translated versions and all discrepancies were reconciled to prepare the final Bengali version of this questionnaire. The face validity of this Bengali version questionnaire was ensured by a five-membered group of experts in our institute and was found to be satisfactory. To evaluate internal consistency, the questionnaire was then administered among thirty randomly chosen volunteers who fulfilled similar inclusion/exclusion criteria and were not included in the final study sample. Based on their responses Cronbach's alpha was calculated and it was 0.74.

      2.4 Operational definitions

      Fully immunized were defined as those children who received all the recommended doses of vaccines for their age as per the National Immunization Schedule at the time of the study.
      • Arora S.
      National immunization schedule India: a review.
      Partially immunized were defined as those children who defaulted one or more doses of recommended vaccines for their age.
      Unimmunized children were those who did not receive any recommended vaccine.
      Partially- and un-immunized children were merged to express incomplete immunization.

      2.5 Data acquisition

      Primary caregivers of eligible children were face-to-face interviewed using the final version of the questionnaires. Written informed consent was taken from each participant. The caregivers understood that they have to participate in the study voluntarily and due efforts will be made to conceal their identity and responses, but anonymity cannot be guaranteed. Caregivers who dissented were excluded, and the next eligible child was selected. Participants who failed to provide all the necessary information correctly despite repeated explanations of the question/questions in his/her language were also excluded. Interviews included three sections of questionnaires that covered socio-demographic profile, immunization status, and VHS questions of WHO-SAGE Working groups. The immunization status was documented as fully immunized, partially immunized, or unimmunized. The WHO-SAGE Working Groups developed three different types of survey questions for identifying VH. The present study used ten Likert scale questions as shown in Fig. 1. Questions were assessed with 5-points, ranging from strongly agree to strongly disagree. The responses to positively-posed questions L1-L7 and negatively-posed L8-L10 were flipped so that higher responses on the Likert scale were indicative of greater vaccine hesitancy. Subsequently, the sum score was calculated across all the 10 Likert-VHS questions. The responses to each question ranged from 1 to 5, so the total score could range from minimum points of 10 to maximum points of 50. Depending on the distribution of these sum scores, participants were categorized evenly into the tertiles of vaccine hesitancy as bottom third, middle third, and top third. The participants in the top thirds were designated as vaccine-hesitant and the rest were considered non-hesitant in the dataset.
      Fig. 1
      Fig. 1Outline of responses to Vaccine Hesitancy questionnaire developed by World Health Organization (WHO) Strategic Advisory Group Experts on Immunization (SAGE).

      2.6 Statistical analysis

      Data were analyzed by SPSS version-25. All tests were two-sided and a p-value of <0.05 was considered statistically significant. Bivariate and multivariate logistic regression was carried out for each of the outcomes (incomplete immunization and VH) separately, to identify their independent predictors. Variables that were significant in the bivariate logistic regression analysis at p-value of <0.05 were included and retained in the multivariate logistic regression model. Prior to fitting the multivariate model, presence of multicollinearity between the covariates was assessed by measuring the variance inflation factor (VIF), and no significant multicollinearity was detected (VIF<5). The forward LR method was used for multivariate logistic regression fitting in SPSS version-25 and the Hosmer-Lemeshow goodness-of-fit statistic was used to measure the calibration of each of the models (p = 0.186 for incomplete immunization and p = 0.231 for VH). After fitting the models, Nagelkerke's R2 values were 0.346 for the incomplete immunization model and 0.413 for the VH model. Adjusted odds ratios (AORs) with their corresponding 95% CIs were used to report the strength of association between dependent and independent variables.

      2.7 Ethical considerations

      Ethical clearance was obtained from the Institutional Ethics Committee (IEC). All procedures contributing to this research comply with the relevant national ethical guidelines in human experimentation and the principles of the Helsinki declarations with its’ later amendments.

      3. RESULTS

      3.1 Profile of study population

      A total of 2136 eligible children were enrolled. Among them, 1.69% were excluded from the assessment of immunization status (23 parents did not give consent and 13 parents could not provide adequate information). The median age of the included children for assessment of the immunization status (n = 2100) was 41 months (IQR: 20–58 months) with the majority belonging to the age group >47 months (44.9%). About 70% of children were male, 56.2% hailed from rural areas and the rest had urban dwellings. Approximately 52.0% were Muslim, 47.5% were Hindu with majorities from nuclear families (62.1%), and mostly belonged to lower (class-IV) or upper-lower (class-V) socioeconomic status. Most of them (77.4%) were delivered at government hospitals while about 10% were borne at home. Most of the mothers (81%) were aged between 20 and 35 years and 11% of them were below the twenties with the majority being primigravida (45.6%) or second-gravida (35.2%). In this study cohort, the proportion of mothers and fathers educated up to middle school were 39.7% and 36.4% respectively. Most of the fathers (40.7%) were skilled workers or government/private jobholders, whereas the majority of mothers (31.3%) were homemakers (Table 1).
      Table 1Distribution of determinants for Immunization status and Vaccine Hesitancy status.
      INDEPENDENT VARIABLESCATEGORYIMMUNIZATION STATUSVACCINE HESITANCY STATUS
      Total (%) N= 2100FULLY IMMUNIZEDTotal (%) N= 1678VACCINE HESITANT
      No (%) n=397 (18.9)Yes (%) n=1703 (81.1)Yes (%) n=698 (41.6)No (%) n=980 (58.4)
      Age<24 months623 (29.7)73 (11.7)550 (88.3)543 (32.4)225 (41.4)318 (58.6)
      24–47 months534 (25.4)106 (19.8)428 (80.2)413 (24.6)196 (47.5)217 (52.5)
      >47 months943 (44.9)218 (23.4)725 (77.6)722 (43.0)277 (38.4)445 (61.6)
      GenderFemale634 (30.2)153 (24.1)481 (75.9)609 (36.3)255 (41.9)354 (58.1)
      Male1466 (69.8)244 (16.6)1222 (83.4)1069 (63.7)443 (41.4)626 (58.6)
      ResidenceRural1180 (56.2)221 (18.7)959 (81.3)918 (54.7)401 (43.7)517 (56.3)
      Urban920 (43.8)176 (19.1)744 (80.9)760 (45.3)297 (39.1)463 (60.9)
      ReligionMuslim1092 (52.0)202 (18.5)890 (81.5)836 (49.8)357 (42.7)479 (57.3)
      Hindu999 (47.5)192 (19.2)807 (80.8)834 (49.7)338 (40.5)496 (59.5)
      Others9 (0.5)3 (33.3)6 (66.6)8 (0.5)3 (37.5)5 (62.5)
      Family TypeNuclear1304 (62.1)263 (20.2)1041 (79.8)1079 (64.3)601 (55.7)478 (44.3)
      Joint796 (37.9)134 (16.8)662 (83.2)599 (35.7)97 (16.2)502 (83.8)
      Birth Order1958 (45.6)158 (16.5)800 (83.5)723 (43.1)323 (44.7)400 (55.3)
      2739 (35.2)163 (21.9)576 (78.1)653 (38.9)276 (42.2)377 (57.8)
      ≥3403 (19.2)76 (18.8)327 (81.2)302 (18)99 (32.8)203 (67.2)
      Mother's age<20 years231 (11)62 (26.9)169 (73.1)153 (9.1)72 (47.1)81 (52.9)
      20–35 years1701 (81)307 (18.1)1394 (81.9)1388 (82.7)570 (41.4)807 (58.6)
      >35 years168 (8)28 (16.7)140 (83.3)137 (8.2)47 (34.3)90 (65.7)
      Mother's educationIlliterate237 (11.3)107 (44.9)130 (55.1)122 (7.3)78 (64.2)44 (35.8)
      Middle school834 (39.7)155 (18.6)679 (81.4)734 (43.7)404 (55.1)330 (44.9)
      Secondary603 (28.7)90 (14.9)513 (85.1)443 (26.4)105 (23.7)338 (76.3)
      ≥ Higher secondary426 (20.3)45 (10.5)381 (89.5)379 (226)111 (29.3)268 (70.7)
      Mother's occupationHomemaker657 (31.3)134 (20.4)523 (79.6)570 (34.0)204 (35.7)366 (64.3)
      Agriculture312 (14.8)87 (27.8)225 (72.2)221 (13.3)107 (48.4)114 (51.6)
      Unskilled worker302 (14.4)72 (23.9)230 (76.1)262 (15.5)126 (48.1)136 (51.9)
      Job/Skilled worker615 (29.3)86 (14)529 (86)602 (35.8)252 (41.8)350 (58.2)
      Others214 (10.2)18 (8.4)196 (91.6)23 (1.4)9 (39.1)14 (60.9)
      Father's educationIlliterate265(12.6)73 (27.5)192 (72.5)129 (7.8)65 (50.4)64 (49.6)
      Middle school764 (36.4)199 (26.1)565 (73.9)648 (38.5)327 (50.5)321 (49.5)
      Secondary447 (21.3)77 (17.2)370 (82.8)397 (23.7)147 (37.1)250 (62.9)
      ≥ Higher secondary624 (29.7)48 (7.7)576 (92.3)504 (30.0)159 (31.5)345 (68.5)
      Father's occupationUnemployed153 (7.3)34 (22.5)119 (77.5)137 (8.2)81 (59.1)56 (40.9)
      Unskilled worker260 (12.4)87 (33.5)173 (66.5)196 (11.7)97 (49.5)99 (50.5)
      Agriculture399 (19)67 (16.9)332 (83.1)287 (17.1)126 (43.9)161 (56.1)
      Job/Skilled worker855 (40.7)47 (5.5)808 (94.5)704 (41.9)267 (37.9)437 (62.1)
      Others433 (20.6)162 (37.4)271 (62.6)354 (21.1)127 (35.8)227 (64.1)
      SEC
      Socioeconomic class (SEC) was assessed by Modified BG Prasad scale for rural and Modified Kuppuswamy Scale for urban residents.
      Lower (V)878 (41.8)218 (24.8)660 (75.2)651 (38.8)332 (50.9)319 (49.1)
      Upper-Lower (IV)863 (41.1)162 (18.8)701 (81.2)720 (42.9)261 (36.2)459 (63.8)
      ≥Lower-Middle (III)359 (17.1)17 (4.8)342 (95.2)307 (18.3)106 (34.5)201 (65.5)
      Place of birthGovt. Hospital1625 (77.4)172 (10.6)1453 (89.4)1283 (76.5)502 (39.1)781 (60.9)
      Private Hospital265 (12.6)107 (40.3)158 (59.7)239 (14.2)119 (49.8)120 (50.2)
      Home210 (10)118 (56.2)92 (43.8)156 (9.3)77 (49.3)79(50.7)
      Vaccination cardAvailable1917 (91.3)242 (12.6)1675 (87.4)1587 (94.6)655 (41.3)932 (58.7)
      Not-Available183 (8.7)155 (84.9)28 (15.1)91 (5.4)43 (47.2)48 (52.8)
      Vaccine Hesitant (N = 1678)Yes698 (41.6)197 (28.2)501 (77.8)
      No980 (58.4)123 (12.6)857 (87.4)
      a Socioeconomic class (SEC) was assessed by Modified BG Prasad scale for rural and Modified Kuppuswamy Scale for urban residents.

      3.2 Immunization coverage and vaccine-hesitancy status

      During the interview, 91.3% had immunization cards and the recall method of parents was used to assess the immunization status of the rest. The proportion of fully immunized, partially immunized and unimmunized children were 81.1% (n = 1703), 17.2% (n = 361) and 1.7% (n = 36) respectively. Among fully immunized children 83.2% adhered to the recommended schedule for vaccines. Coverage of individual vaccines is depicted in Fig. 2, showing the highest for BCG (98.3%) and lowest for DPT/Pentavalent and Measles 2nd booster dose (85.6% and 81.1% respectively). The most frequently reported Adverse Events Following Immunization (AEFI) were fever, vaccination site swellings, etc. Measles and DPT/Pentavalent vaccines were most commonly implicated vaccines for AEFI.
      Fig. 2
      Fig. 2Individual vaccine coverage of eligible children. (BCG: Bacille Calmette-Guérin; OPV: Oral poliovirus vaccine; Hep-B: Hepatitis-B; DPT: Diphtheria-Tetanus and Pertussis; MCV: Measles-containing-vaccine).
      The proportion of non-responders to the VH survey was about 20%. Among the included participants (n = 1678), mothers were the main respondents (98.4%) followed by fathers and other caregivers in 1.3% and 0.3% of cases. The prevalence of vaccine-hesitant parents (VHPs) was 41.6%. The proportion of complete immunization was 71.8% and 87.4% in children with VHPs and non-VHPs respectively.

      3.3 Response to vaccine-hesitancy survey questionnaire

      The participants' responses to the Likert-VHS questionairre [L1-L10] is depicted in Fig. 1. Almost all responders agreed or strongly agreed that “Childhood vaccines are effective” (99%), “Childhood vaccines are important for my child's health” (98%), and “All childhood vaccines offered by the government program in my community are beneficial” (95%). The majority of VHPs were concerned about serious adverse effects of vaccines (41%), believed some vaccines are not needed for diseases that are not common now (26%) or feared about new vaccines carried more risk than old vaccines (16%).

      3.4 Determinants of incomplete immunization and vaccine-hesitancy

      We have studied different socio-demographic predictors of incomplete immunization and vaccine hesitancy. On multivariate analysis, female gender (AOR = 1.527, 95% CI:1.296–1.938), illiterate mothers (AOR = 8.371, 95% CI: 2.410–29.073), socioeconomic status class-4 (AOR = 4.964, 95% CI: 1.115–22.094) and birth at home (AOR = 5.052, 95% CI: 2.677–9.532) or private hospital (AOR = 15.102, 95% CI: 7.40–30.821) were statistically significant predictors for incomplete immunization. On the other hand, maternal education below the secondary level (Illiterate- AOR = 7.093; 95% CI: 2.172–26.043; Middle school- AOR = 4.185; 95% CI: 1.719–19.307) and those belonging to nuclear families (AOR = 1.901; 95% CI: 1.214–3.796) were found to be significant predictors of VH (Table 2).
      Table 2Logistic Regression Model showing determinants of Incomplete immunization and Vaccine Hesitancy.
      INDEPENDENT VARIABLESCATEGORYINCOMPLETE IMMUNIZATIONVACCINE HESITANCY STATUS
      Bivariate p-valueMultivariate AnalysisBivariate p-valueMultivariate Analysis
      AOR (95% CI)p-valueAOR (95% CI)p-Value
      Age<24 months0.0640.052
      24–47 months0.0590.061
      >47 months (ref)
      GenderFemale<0.0011.527 (1.296–1.938)0.0290.863
      Male (ref)1
      ResidenceRural0.8900.065
      Urban (ref)
      ReligionMuslim0.8910.736
      Hindu0.6570.647
      Others (ref)
      Family typeNuclear0.236<0.0011.901(1.214–3.796)0.041
      Joint (ref)1
      Birth order10.0630.0101.018 (0.574–2.973)0.059
      20.3270.0470.931 (0.247–3.158)0.173
      ≥3 (ref)1
      Mother's age<20 years0.1170.088
      20–35 years0.7210.117
      >35 years (ref)
      Mother's educationIlliterate<0.0018.371 (2.410–29.073)0.001<0.0017.093 (2.172–26.043)<0.001
      Middle school<0.0012.700 (0.847–8.607)0.093<0.0014.185 (1.719–19.307)0.010
      Secondary0.0021.072 (0.323–3.558)0.9090.0341.029 (0.296–4.093)0.061
      ≥ Higher secondary (ref)11
      Mother's occupationHomemaker0.0232.435 (0.529–11.200)0.2530.058
      Agriculture0.0010.776 (0.290–2.080)0.6150.178
      Unskilled worker0.0481.120 (0.408–3.075)0.8250.342
      Job/Skilled worker0.0590.813 (0.336–1.968)0.6460.853
      Others (ref)1
      Father's educationIlliterate<0.0011.114 (0.331–3.758)0.861<0.0011.135 (0.297–2.846)0.195
      Middle school0.0031.966 (0.722–5.359)0.1860.0491.173 (0.358–4.782)0.741
      Secondary0.0291.315 (0.491–3.521)0.5860.7031.019 (0.221–2.979)0.931
      ≥ Higher secondary (ref)11
      Father's occupationUnemployed/Unskilled worker0.0310.501 (0.100–2.512)0.4010.461
      Agriculture0.0141.930 (0.619–6.017)0.2570.098
      Job/Skilled worker0.1431.096 (0.399–3.012)0.8590.294
      Others (ref)1
      SEC
      Socioeconomic class (SEC) was assessed by Modified BG Prasad scale for rural and Modified Kuppuswamy Scale for urban residents.
      Lower (V)<0.0014.964 (1.115–22.094)0.035<0.0012.9 (1.075–18.947)0.071
      Upper-Lower (IV)0.0193.590 (0.933–13.819)0.063<0.0011.017 (0.057–11.942)0.069
      ≥ Lower-Middle (III) (ref)11
      Place of birthPrivate Hospital<0.00115.102 (7.40–30.821)<0.0010.0011.019 (0.437–2.158)0.091
      Home<0.0015.052 (2.677–9.532)<0.0010.0171.163 (0.522–3.351)0.116
      Govt. Hospital (ref)11
      Vaccine CardAvailable0.0690.263
      Not-Available (ref)
      Vaccine HesitantYes0.0391.06 (0.736–1.013)0.056
      No (ref)1
      (Abbreviations: AOR = adjusted odds ratio; CI = confident interval).
      a Socioeconomic class (SEC) was assessed by Modified BG Prasad scale for rural and Modified Kuppuswamy Scale for urban residents.

      4. Discussion

      The present study identified the prevalence of complete immunization among children aged 1–5 years was 81.1%. It is quite satisfactory compared to the average national coverage.

      International Institute for Population Sciences (IIPS) and ICF. National Family Health Survey (NFHS-5), 2019-20: India. Mumbai: International Institute for Population Sciences. Available from: http://rchiips.org/nfhs/index.shtml. [Assessed on, 10 27, 2021].

      The underlying success might be due to optimal utilization of the network of sub-centres, primary health facilities, and community health centres in rural areas to deliver free-of-cost routine vaccines under UIP. In addition, the utilization of systematic outreach vaccination services to increase accessibility to routine immunization coverage where community health workers (e.g., Anganwadi workers) are directly involved in delivering vaccines as well as community mobilization. Public awareness-related programs have also played a significant role in generating demand for vaccine uptake.
      • El Arifeen S.
      • Christou A.
      • Reichenbach L.
      • et al.
      Community-based approaches and partnerships: innovations in health-service delivery in Bangladesh [published correction appears in Lancet.
      Moreover, the information based on the maternal recall method has low specificity and might overestimate immunization coverage.
      • Dansereau E.
      • Brown D.
      • Stashko L.
      • Danovaro-Holliday M.C.
      A systematic review of the agreement of recall, home-based records, facility records, BCG scar, and serology for ascertaining vaccination status in low and middle-income countries.
      In this study, coverage for the BCG vaccine was highest as it is given immediately after birth at healthcare facilities. The gradual decrease in the coverage for measles and DPT/pentavalent booster doses could be due to longer time intervals between these vaccines, leading mothers to forget the subsequent doses. The other reasons could be due to lack of understanding of the need for vaccination, loss of motivation, and previous AEFI like fever, vaccination site swellings, etc.
      • WHO
      Epidemiology of the unimmunized child: findings from the grey literature: IMMUNIZATION basics project.
      The majority of included children were male and the gender of the child was an important determinant of immunization status as in other studies.
      • Feletto M.
      • Sharkey A.
      The influence of gender on immunisation: using an ecological framework to examine intersecting inequities and pathways to change.
      ,
      • Singh A.
      Gender Based Within-Household Inequality in Childhood Immunization in India: changes over time and across regions. [published correction appears in PLoS One.
      This difference might be due to gender discrimination that exists in our society. Studies from different parts of India also found significant differences in terms of outpatient (65% males vs 35% females) and inpatient attendance (84% males vs 16% females), delays in bringing the ill female children to medical attention, shorter duration of admission, and more likelihood of vaccine drop out in girl children.
      • Singh A.
      Gender Based Within-Household Inequality in Childhood Immunization in India: changes over time and across regions. [published correction appears in PLoS One.
      ,
      • Khera R.
      • Jain S.
      • Lodha R.
      • Ramakrishnan S.
      Gender bias in child care and child health: global patterns.
      Home delivery was found to be a significant risk factor for incomplete immunization concurrent with other Indian and global studies.
      • Pandey S.
      • Ranjan A.
      • Singh C.M.
      • Kumar P.
      • Ahmad S.
      • Agrawal N.
      Socio-demographic determinants of childhood immunization coverage in rural population of Bhojpur district of Bihar, India.
      ,
      • Allan S.
      • Adetifa I.M.O.
      • Abbas K.
      Inequities in childhood immunisation coverage associated with socioeconomic, geographic, maternal, child, and place of birth characteristics in Kenya.
      The first dose of vaccination is given just after birth for institutional deliveries and mothers are counselled regarding the importance of immunization and subsequent vaccination. The current study also found that children born at government hospitals were better immunized than those born at private hospitals. Vaccines provided in private hospitals are not free of cost. Neither do they work under any Government mandate nor receive any financial or policy incentive benefit to deliver immunization. Furthermore, researchers also found lack of quality of care and management including vaccine preservation and unsafe injection practices, inadequate knowledge of health workers, and exchange of health information with the public sector.
      • Hagan J.E.
      • Gaonkar N.
      • Doshi V.
      • et al.
      Knowledge, attitudes, and practices of private sector immunization service providers in Gujarat, India.
      This might generate greater odds of being incompletely immunized. These gaps can be addressed through providing training and support to private immunization service providers for capacity-building, ensuring appropriate vaccine handling and storage standards, provision of public-sector vaccines free of cost while receiving a pre-specified amount of operational costs from the public sector, improving record-keeping and reporting, exchange of health information between the public and the private sector, and optimize this collaboration via exploring innovative and mutually beneficial partnerships, as urged by WHO.
      World Health Organization
      Engagement of Private/nongovernmental Providers in Immunization Service Delivery.
      Compared to educated mothers, mothers with no or lesser formal education were more likely to have incompletely immunized children. The capacity of an individual to obtain, process, and understand basic health information and services required to make appropriate health decisions is called health literacy. The positive relation between maternal health literacy and childhood vaccination has been well established in the literature.
      • Johri M.
      • Subramanian S.V.
      • Sylvestre M.P.
      • et al.
      Association between maternal health literacy and child vaccination in India: a cross-sectional study.
      Educated parents have better health-care-seeking behaviour and knowledge to understand the recommended immunization schedule. Furthermore, educated parents who belong to the upper socio-economic class have better access to health and immunization services. Although the immunizations services are provided free of cost at public health facilities, the cost of transportation and loss of daily income might be associated with low demand for vaccination, especially for families with poor socioeconomic status.
      • Srivastava S.
      • Fledderjohann J.
      • Upadhyay A.K.
      Explaining socioeconomic inequalities in immunisation coverage in India: new insights from the fourth National Family Health Survey (2015-16).
      ,
      • Srivastava S.
      • Kumar P.
      • Chauhan S.
      • Banerjee A.
      Household expenditure for immunization among children in India: a two-part model approach.
      Vaccine hesitancy among caregivers, an important risk factor for childhood vaccination, is as old as vaccines themselves, ranging from the delay of one or more vaccines to total refusal to vaccinate. With India's large annual cohort of 26 million infants born every year, there is greater urgency to address the issue of vaccine hesitancy and its influence on population-level immunization coverage.
      In our study, the prevalence of VHPs was 41.6%, concurrent with other study findings.
      • Alsubaie S.S.
      • Gosadi I.M.
      • Alsaadi B.M.
      • et al.
      Vaccine hesitancy among Saudi parents and its determinants. Result from the WHO SAGE working group on vaccine hesitancy survey tool.
      • Dubé E.
      • Gagnon D.
      • Zhou Z.
      • Deceuninck G.
      Parental vaccine hesitancy in quebec (Canada).
      • Forbes T.A.
      • McMinn A.
      • Crawford N.
      • et al.
      Vaccination uptake by vaccine-hesitant parents attending a specialist immunization clinic in Australia.
      However, it was in contrast to a global study from India which found the prevalence to be only 12.5%.
      • Larson H.J.
      • Schulz W.S.
      • Tucker J.D.
      • Smith D.M.
      Measuring vaccine confidence: introducing a global vaccine confidence index.
      This difference could be attributed to the variation in data collection methodology. The global study was conducted with the help of computer-assisted telephone interviews, compared to our study where data was collected in a more personalized nature via face-to-face interviews which led subjects to be more comfortable and forthcoming in their responses. The proportion of incomplete immunization was significantly higher in children with VHPs (28.2%) compared to non-VHPs (12.6%), concurrent with the other studies from developing countries.
      • Cherian V.
      • Saini N.K.
      • Sharma A.K.
      • Philip J.
      Prevalence and predictors of vaccine hesitancy in an urbanized agglomeration of New Delhi, India [published online ahead of print, 2021 Feb 17].
      ,
      • Alsubaie S.S.
      • Gosadi I.M.
      • Alsaadi B.M.
      • et al.
      Vaccine hesitancy among Saudi parents and its determinants. Result from the WHO SAGE working group on vaccine hesitancy survey tool.
      Though VH was not found to be a significant predictor for incomplete immunization in multivariate analysis, a significant relationship was found in other global studies.
      • Masters N.B.
      • Tefera Y.A.
      • Wagner A.L.
      • Boulton M.L.
      Vaccine hesitancy among caregivers and association with childhood vaccination timeliness in Addis Ababa, Ethiopia.
      ,
      • Opel D.J.
      • Taylor J.A.
      • Zhou C.
      • Catz S.
      • Myaing M.
      • Mangione-Smith R.
      The relationship between parent attitudes about childhood vaccines survey scores and future child immunization status: a validation study.
      This might be due to the small sample size, or it could reflect the real scenario in our study population.
      This study found that mothers generally agreed on the benefits of vaccines but expressed concerns about severe adverse effects of vaccines, the safety of new vaccines, the necessity of administering vaccines for diseases that are not common now, and multiple vaccine co-administration during a single visit. Studies from India
      • Dasgupta P.
      • Bhattacherjee S.
      • Mukherjee A.
      • Dasgupta S.
      Vaccine hesitancy for childhood vaccinations in slum areas of Siliguri, India.
      ,
      • Sankaranarayanan S.
      • Jayaraman A.
      • Gopichandran V.
      Assessment of vaccine hesitancy among parents of children between 1 and 5 Years of age at a tertiary care hospital in Chennai.
      China
      • Ren J.
      • Wagner A.L.
      • Zheng A.
      • et al.
      The demographics of vaccine hesitancy in Shanghai, China.
      and Ethiopia
      • Masters N.B.
      • Tefera Y.A.
      • Wagner A.L.
      • Boulton M.L.
      Vaccine hesitancy among caregivers and association with childhood vaccination timeliness in Addis Ababa, Ethiopia.
      found positive attitudes towards vaccines as safe, effective, and important, but similarly expressed negative concerns about the adverse effects and efficacy of new vaccines.
      The reason for increased positive awareness towards vaccines might be due to the widespread use of social media, mass media, community-based mass awareness campaigns, and behaviour change programs.
      • Dubé E.
      • Leask J.
      • Wolff B.
      • et al.
      The WHO tailoring immunization programmes (TIP) approach: review of implementation to date.
      Healthcare professionals play an important role in providing information with a positive impact on the level of knowledge and attitudes towards vaccination among parents and thereby reducing their VH.
      • Bianco A.
      • Della Polla G.
      • Angelillo S.
      • Pelullo C.P.
      • Licata F.
      • Angelillo I.F.
      Parental COVID-19 vaccine hesitancy: a cross-sectional survey in Italy.
      • Della Polla G.
      • Pelullo C.P.
      • Napolitano F.
      • Angelillo I.F.
      HPV vaccine hesitancy among parents in Italy: a cross-sectional study.
      • Greenberg J.
      • Dubé E.
      • Driedger M.
      Vaccine hesitancy: in search of the risk communication comfort zone.
      The quality interaction between healthcare professionals and parents should be a two-way process, where listening to the perceptions of caregivers is as important as providing information to mitigate the negative influences of vaccines and increase vaccine uptake.
      • Shen S.C.
      • Dubey V.
      Addressing vaccine hesitancy: clinical guidance for primary care physicians working with parents.
      Additionally, as seen in this study, those who previously experienced AEFI, were the most common reason for vaccine hesitancy or refusal. Prior counselling about possible adverse effects by healthcare workers will mitigate vaccine hesitancy and improve immunization coverage. The continuous monitoring of AEFI by an active surveillance system is of prime importance in building trust and confidence to increase vaccine acceptance.
      • Scherer L.D.
      • Shaffer V.A.
      • Patel N.
      • Zikmund-Fisher B.J.
      Can the vaccine adverse event reporting system be used to increase vaccine acceptance and trust?.
      VH can vary according to the vaccine involved and a significant proportion of the caregivers in our study were found to be more hesitant to new vaccines, similar to the other study findings.
      • Masters N.B.
      • Tefera Y.A.
      • Wagner A.L.
      • Boulton M.L.
      Vaccine hesitancy among caregivers and association with childhood vaccination timeliness in Addis Ababa, Ethiopia.
      ,
      • Kaarthigeyan K.
      Cervical cancer in India and HPV vaccination.
      Maternal education was a significant predictor of vaccine hesitancy. Educated mothers are more likely to understand the importance of timely vaccination, interact more freely with health workers and develop positive attitudes towards vaccines.
      • Dasgupta P.
      • Bhattacherjee S.
      • Mukherjee A.
      • Dasgupta S.
      Vaccine hesitancy for childhood vaccinations in slum areas of Siliguri, India.
      ,
      • Sankaranarayanan S.
      • Jayaraman A.
      • Gopichandran V.
      Assessment of vaccine hesitancy among parents of children between 1 and 5 Years of age at a tertiary care hospital in Chennai.
      ,
      • Priya P.K.
      • Pathak V.K.
      • Giri A.K.
      Vaccination coverage and vaccine hesitancy among vulnerable population of India.
      However, a study from a developed country found that higher education was associated with access to unfavourable information about vaccines and increased vaccine hesitancy.
      • McNutt L.A.
      • Desemone C.
      • DeNicola E.
      • El Chebib H.
      • Nadeau J.A.
      • Bednarczyk R.A.
      • et al.
      Affluence as a predictor of vaccine refusal and underimmunization in California private kindergartens.
      This study showed that mothers of nuclear families were more VH than those from joint families, concurrent with other study findings from similar settings.
      • Cherian V.
      • Saini N.K.
      • Sharma A.K.
      • Philip J.
      Prevalence and predictors of vaccine hesitancy in an urbanized agglomeration of New Delhi, India [published online ahead of print, 2021 Feb 17].
      ,
      • McNutt L.A.
      • Desemone C.
      • DeNicola E.
      • El Chebib H.
      • Nadeau J.A.
      • Bednarczyk R.A.
      • et al.
      Affluence as a predictor of vaccine refusal and underimmunization in California private kindergartens.
      This could be explained by the fact that nuclear families usually do not have significant guidance from other experienced senior family members in making decisions about a child's health attributed to vaccination insecurity. Often the problem is aggravated if the mother is the only caregiver, is busy due to household or other jobs, is sick, pregnant, or has to take care of other children. It results in unnecessary delay and reluctance to take her child for vaccination.
      • Srividya J.
      • Patel A.E.
      • Sunil Kumar D.R.
      Vaccine hesitancy for childhood vaccinations in urban slums of Bengaluru rural district, Karnataka.
      • Kumar A.
      • Ram F.
      Influence of family structure on child health: evidence from India.
      This diversity indicates that the determinants of vaccine hesitancy vary in countries with different socio-economic and cultural contexts.

      4.1 Strengths and limitations

      This study not only emphasized the magnitude of the issue of incomplete immunization and VH but also unravel its contributing factors which will help public health care providers with a roadmap to prioritize resources and focus on the preventable measures to increase vaccine compliance. The survey utilized the WHO-SAGE Working Group standardized and validated Likert scale questionnaire to determine VH. This provides a standard scale for comparison with other countries globally. Current study has a few limitations. Although the recall method to estimate the vaccination coverage in the absence of record-based data has already been validated in developing countries, it may be prone to recall bias and overestimate the vaccination coverage. Limited data collected on socio-demographic information could have missed other important variables affecting immunization status and VH. We could not test open-ended and closed-ended scale questions of the WHO-SAGE survey tool due to participants’ time constraints, and for the same, relevant information from the non-responders could not be obtained to perform a comparative analysis between the responders and non-responders to quantify the response bias. Being a single-centre, cross-sectional, and interview-based in nature this study could not well establish the temporal relations between the variables, and the possibility of social-desirability bias could not be ruled out. Hence, further multi-centric prospective studies may be deemed necessary before generalizing our findings to a larger population.

      5. Conclusions

      Despite the current study showing satisfactory immunization coverage among children, adherence to recommended schedule was not optimal. The significant predictors of incomplete immunization found in this study like maternal educational level, socio-economic status, gender of the child, and place of delivery can be alleviated through appropriate interventions such as health education, ensuring institutional births, and free health-service delivery expansion. VH among caregivers is a major concern for incomplete immunization coverage. The predictors of vaccine hesitancy in our study were maternal education and family type which can be tackled by involving health workers to improve their counselling and communication skills. Different communities have different determinants of immunization status and VH. There is always a need to identify these local determinants for designing strategies to improve the quality and effectiveness of vaccination programs on a local basis.

      Presentation at a meeting

      None.

      Financial support and sponsorship

      Nil.

      Ethics approval

      The study got permission from the Institutional Ethics Committee (IEC) of Midnapore Medical College with Ref No- MMC/IEC/2018/A-20.

      Authors’ contributions

      This research was carried out in collaboration with all authors. Conceptualization and study design: AG, PKD, PG, and SM. Data acquisition: AG, SA, and SKH. Analysis and interpretation of data: AG, PKD, SM, and PG. Drafting the manuscript: AG, SA, SKH, and SM. Revising the manuscript critically: PKD and PG. All authors read and approved the final manuscript.

      Declaration of competing interest

      There are no conflicts of interest.

      Acknowledgments

      The researchers would like to thank all the participants for their willingness to take part in this study. We are also grateful to Dr. Ripan Saha (M.D. Community Medicine, Senior Resident) and Ms. Meghna Mukherjee (MSc, Statistician cum Tutor), Department of Community Medicine, IPGMER & SSKM Hospital, Kolkata, India for their potential inputs in statistical analysis.

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