STATISTICAL ANALYSIS OF FACTORS INFLUENCING VACCINE ACCEPTANCE AMONG ADULTS IN IBADAN METROPOLIS, NIGERIA

Background to the Study

Why Vaccination Still Matters

Vaccination remains one of the most cost-effective public health interventions ever developed. By training the immune system to recognise and respond to specific pathogens, vaccines have driven the eradication of smallpox, brought the world close to eliminating poliomyelitis, and sharply cut illness and death from measles, tetanus, diphtheria, and hepatitis B. Global immunisation efforts, coordinated in large part through WHO-led programmes, are credited with saving several million lives every year, making immunisation one of the highest-return investments available in global health. Even so, vaccine-preventable diseases persist stubbornly in low- and middle-income countries, where immunisation coverage still lags behind the levels needed for reliable population protection.

The Rise of Vaccine Hesitancy as a Global Concern

At the centre of this shortfall sits vaccine hesitancy: the delay or refusal of vaccination despite vaccines being readily available. The World Health Organization named vaccine hesitancy one of the top ten threats to global health in 2019, placing it alongside antimicrobial resistance, air pollution, and non-communicable disease. The COVID-19 pandemic then thrust the issue into sharper focus. Even after several safe and effective vaccines were developed in record time, meaningful shares of the population in both wealthy and developing countries delayed or declined vaccination, complicating efforts to reach herd immunity thresholds.

The Nigerian and Ibadan Context

Nigeria, home to an estimated 220 million people, continues to report immunisation coverage well below recommended targets, with adult vaccination for illnesses such as influenza, COVID-19, HPV, and meningococcal disease facing particularly steep challenges that vary by geography, demographic group, religion, and income. Readers interested in the underlying national survey data can consult the DHS Program's official Nigeria survey reports for further context. Ibadan Metropolis, the largest city in West Africa by geographical area and the capital of Oyo State, captures these national dynamics in miniature: a large, densely populated, and demographically varied city where educational attainment, religious affiliation, healthcare access, and media habits differ sharply from one neighbourhood to the next.

The WHO's 3C framework — confidence, complacency, and convenience — offers a useful shorthand for understanding what drives hesitancy: confidence reflects trust in vaccine safety and the health system, complacency reflects a low perceived risk of disease, and convenience reflects how easy or difficult vaccination actually is to access. Beyond this framework, the wider research literature points to health literacy, past adverse vaccine reactions, misinformation circulating on social media, religious and cultural beliefs, fear of side effects, and mistrust of pharmaceutical companies and government agencies as additional, often overlapping, contributors. Statistical analysis is what allows a study like this one to pull these overlapping influences apart and estimate which ones matter most, once the others are held constant.

Statement of the Problem

Vaccines work. That much is well established. Yet acceptance levels in Ibadan Metropolis and across Nigeria more broadly remain below what is needed for community-level protection against most vaccine-preventable diseases, with routine coverage falling short of the 80–90% threshold typically required. Recurring measles outbreaks, the persistence of wild poliovirus transmission in parts of the country until recently, and comparatively low COVID-19 vaccine uptake all point toward a genuine acceptance gap — one that cannot be explained away by vaccine supply shortages alone.

The existing Nigerian literature on vaccine acceptance, while expanding, still has notable blind spots. Much of it concentrates on childhood immunisation, leaving adult vaccine-acceptance behaviour comparatively under-examined. Many studies also rely on small, non-probability samples, which limits how confidently their findings can be generalised. Perhaps most importantly, few Nigerian studies apply multivariate statistical techniques capable of isolating which predictors of vaccine acceptance remain significant once other factors are controlled for. This study was designed specifically to close these gaps, using a large probability sample, multivariate logistic regression, and a comprehensive set of predictor variables to produce statistically defensible evidence on what actually drives adult vaccine acceptance in Ibadan. Without such evidence, public health messaging risks being generic, poorly targeted, or culturally mismatched to the audience it is meant to reach.

Aim and Objectives of the Study

The central aim of this study is to statistically analyse the factors that influence vaccine acceptance among adults living in Ibadan Metropolis, Oyo State, Nigeria.

Specific Objectives

•      Determine the prevalence of vaccine acceptance, hesitancy, and refusal among adult residents of Ibadan Metropolis.

•      Assess the sociodemographic characteristics associated with vaccine acceptance status.

•      Examine health belief constructs — perceived severity, susceptibility, benefits, and barriers — in relation to vaccine acceptance.

•      Determine how trust in healthcare providers, social influence, information sources, and religious affiliation shape vaccine acceptance.

•      Identify the independent predictors of vaccine acceptance using binary logistic regression.

•      Assess whether vaccine acceptance scores differ significantly across educational levels and income groups using ANOVA.

Research Questions

•      What is the prevalence of vaccine acceptance, hesitancy, and refusal among adults in Ibadan Metropolis?

•      Is there a statistically significant association between sociodemographic variables — gender, education, religion, income — and vaccine acceptance?

•      Is there a statistically significant association between prior adverse vaccine experience and vaccine acceptance?

•      What are the independent predictors of vaccine acceptance among adults in Ibadan Metropolis?

•      Do vaccine acceptance scores differ significantly across educational levels and income groups?

Significance of the Study

This study adds statistically grounded, locally relevant evidence to the growing body of vaccine hesitancy research in sub-Saharan Africa, applying binary logistic regression alongside ANOVA and chi-square testing to a well-powered sample of 300 adults drawn from a major Nigerian city. That combination of methods raises the methodological bar for vaccine acceptance research conducted in Nigerian urban settings. For students preparing a related public health, epidemiology, or biostatistics project, ScholarNestHub's project writing support is built to help structure exactly this kind of multivariate, survey-based research from chapter one through to the final analysis.

Beyond the classroom, the findings carry direct public health value for agencies such as the Federal Ministry of Health, the National Primary Health Care Development Agency, the Oyo State Ministry of Health, and partner organisations including WHO, UNICEF, and GAVI. Pinpointing which modifiable factors most strongly predict acceptance allows these bodies to target limited resources where they will do the most good. For community health workers in Ibadan specifically, the study highlights the particular belief systems, trust gaps, and information needs that should inform counselling during routine immunisation visits — insight that is especially timely given ongoing efforts to raise COVID-19 booster uptake, roll out HPV vaccination for adolescent girls, and prepare for future pandemic response campaigns.

Scope of the Study

The study is geographically confined to Ibadan Metropolis, Oyo State, Nigeria, and specifically covers three Local Government Areas: Ibadan North, Ibadan South-West, and Ibadan North-East. Its study population consists of adults aged eighteen years and above. The vaccines considered in assessing acceptance behaviour span routine childhood vaccines from a parental perspective, COVID-19 vaccines, HPV vaccines, meningococcal vaccines, and yellow fever vaccines, with data collection carried out between January and March 2025.

As with any cross-sectional survey, some limitations bound how far the findings can be extended. The design can identify associations but cannot establish causality between the factors examined and vaccine acceptance. Because the outcome relies on self-report, responses around vaccine refusal may be shaped by social desirability bias, particularly in communities where refusal carries some social stigma. The three LGAs studied do not extend to rural Oyo State or other Nigerian geopolitical zones, which limits how broadly the results generalise, and the study measures stated acceptance rather than confirmed vaccination behaviour, a well-documented gap in survey-based health research. Finally, because public discourse around specific vaccines — COVID-19 vaccines especially — continues to evolve, some of the attitudes captured here may reflect a particular moment in that broader conversation.

Operational Definition of Terms

Vaccine Acceptance

The willingness of an individual to receive a recommended vaccine when it is offered, treated in this study as a binary outcome — accept versus hesitant/refuse — derived from specific questionnaire items.

Vaccine Hesitancy

A state of delay or conditional refusal of vaccination despite its availability, marked by ambivalence rather than outright rejection. This definition follows the formulation developed by the WHO SAGE Working Group on Vaccine Hesitancy, the internationally recognised reference point for this concept.

Trust in Healthcare Providers

The extent to which an individual believes that healthcare workers and medical institutions act in their best interests and provide accurate, reliable information about vaccines.

Perceived Vaccine Safety

An individual's subjective judgement of how likely a vaccine is to cause adverse effects or long-term harm, independent of the vaccine's actual, clinically established safety profile.

Social Influence

The degree to which a person's vaccination decisions are shaped by the behaviour, opinions, and advice of family members, peers, community leaders, and religious figures.

Health Belief Model

A psychological framework holding that health behaviour is shaped by perceived susceptibility to disease, perceived severity of disease, perceived benefits of a given health action, perceived barriers to that action, cues to action, and self-efficacy. This model, described in detail by the National Institutes of Health's overview of the Health Belief Model, underpins much of the health-belief measurement used in this study's questionnaire.

Conclusion

Vaccine acceptance in Ibadan Metropolis is not the product of any single factor — it emerges from the interplay of trust, perceived safety, education, social norms, and access to credible information. Recognising that complexity is the first step toward designing interventions that actually move the needle, rather than generic messaging that misses the specific concerns of specific communities. If you are developing a related survey-based project in public health, biostatistics, or health communication, you can explore more statistics and public health project topics on ScholarNestHub to see how a similarly rigorous, multivariate approach can be adapted to your own research questions.

Frequently Asked Questions

1. What percentage of adults in Ibadan accept vaccines, according to this study?

The study found that 67.0% of surveyed adults in Ibadan Metropolis accepted vaccines, while 21.3% were hesitant and 11.7% refused vaccination outright.

2. What is the strongest predictor of vaccine acceptance in this study?

Trust in healthcare providers was the strongest independent predictor identified through binary logistic regression, followed by perceived vaccine safety, educational attainment, and social influence.

3. What does 'vaccine hesitancy' actually mean?

Vaccine hesitancy refers to delaying or conditionally refusing vaccination even when vaccines are available, as defined by the WHO SAGE Working Group on Vaccine Hesitancy. It sits on a spectrum between full acceptance and outright refusal, rather than being a fixed, all-or-nothing position.

4. Why does education level affect vaccine acceptance?

Higher educational attainment is generally associated with greater health literacy, better access to accurate information, and stronger critical evaluation of misinformation, all of which this study found to be linked with higher vaccine acceptance.

5. How was vaccine acceptance measured in this study?

Vaccine acceptance was measured using a validated 28-item structured questionnaire covering sociodemographic characteristics, health beliefs, trust in providers, social influence, safety perceptions, and information sources, administered to 300 adults selected through stratified random sampling.

6. What statistical methods were used to analyse the data?

The study applied descriptive statistics, chi-square tests, binary logistic regression, one-way ANOVA, and Pearson correlation to examine relationships between vaccine acceptance and its potential predictors.

7. Does religion influence vaccine acceptance in Ibadan?

Yes. Chi-square analysis found a statistically significant association between religious affiliation and vaccine acceptance, underscoring the need for culturally and religiously sensitive public health messaging.

8. What role does the Health Belief Model play in vaccine research?

The Health Belief Model explains health behaviour through perceived susceptibility, severity, benefits, and barriers, and it provided the theoretical basis for several of the health-belief items used in this study's questionnaire.

9. Can this study's findings be applied outside Ibadan?

The findings are most directly generalisable to large, demographically diverse Nigerian urban centres with similar characteristics, though the specific weight of each predictor may vary in rural areas or other geopolitical zones not covered by this study.

10. Where can I get help designing a similar public health research project?

Students working on survey-based public health, biostatistics, or health communication projects can get structured writing and analysis support through ScholarNestHub's project writing service, or check the frequently asked questions page for more on how the process works.