Regional variation in COVID-19 vaccine uptake and intention in Nigeria: A computer assisted telephone survey

Background

The novel coronavirus disease caused by the SARS-COV-2 virus became a global pandemic with a disease burden that increased rapidly since December 2019, when the first human case was discovered in Wuhan China [1,2]. Globally, the World Health Organization (WHO) reported a total of 772 million confirmed cases and 6.9 million deaths as of November 19, 2023. In the WHO African region, 47 countries had been affected by the COVID-19 disease with over 6.9 million confirmed cases and 175,000 deaths [3,4]. Nigeria was among the first countries in sub-Saharan Africa to identify COVID-19 cases and had recorded a total of 266,675 confirmed cases and 3,567 deaths as of November 30, 2023 [5].

Nigeria was categorized as one of the 13 high-risk African countries with respect to the spread of COVID-19 and among the vulnerable African nations, given the weak state of the healthcare system [6]. To mitigate the spread of COVID-19 globally, various public health preventive measures and non-pharmaceutical intervention (NPIs) were implemented in line with the WHO guidelines. Some of the measures included restriction of movement such as lockdowns, promotion of respiratory hygiene (masking, coughing/sneezing etiquette) and hand hygiene practices [7].

Despite these preventive measures for COVID-19, cases continued to rise in Nigeria and other high-risk nations suggesting community transmission of the disease. One of the important preventive measures to reduce the community spread and curtail adverse effects of infectious diseases without definitive treatment such as COVID-19 is by improving the herd immunity of the community through vaccination. Vaccines are biological preparation that confers immunity or protection to individuals against certain infectious organisms. They also prevent and reduce the spread of infection by improving population level immunity known as herd immunity. This implies that when a large proportion of a population are immunized, they confer protection on the unimmunized in that population thereby breaking the chain of transmission of the infection and hindering further spread of the disease [8–10].

In response to the urgent need to control the spread of the virus, there was a need for prompt and expedited development of the SARS-COV-2 vaccine which was achieved within one year of the onset of the pandemic as against the usual development and commercialization of vaccine which takes at least 5 years [11]. As at December, 2022, over 60 vaccines underwent clinical trial with about 34 available for public use- including Pfizer BioNTech, Moderna, Johnson and Johnson, Astrazeneca, Janssen, Sinopharm, BIBP, Sputnik V, CoronaVac, Novavax, Covaxin etc [12]. As of 4 December 2022, a total of 291 million people in the African Region had completed the primary COVID-19 vaccination series, representing 24.9% of the Region’s population [3].

On March 2, 2021, the Federal Government of Nigeria received 3.92 million doses of the Oxford/AstraZeneca vaccine, shipped via the COVAX Facility, which was a partnership between Coalition for Epidemic Preparedness Innovations (CEPI), GAVI, UNICEF and WHO [13]. The first and second phases of vaccination commenced on March 5, and August 17, 2021 respectively [13,14]. The Federal government of Nigeria started by vaccinating frontline healthcare workers, the highest-priority recipients, followed by strategic leaders and then the general population [15]. However, the intervention was met with hesitancy and resistance by the general Nigerian populace similar to many countries around the world. The accelerated development of the vaccine created a lack of trust in the world health governing body, as well as national governments, as to the effectiveness and safety of the COVID-19 vaccine [10,16,17]. There was also heightened public anxieties as regards to possible side effects of the vaccine which are not yet known to scientists or experienced by anyone [17,18]. Unfortunately, to worsen the hesitancy to vaccine uptake in Nigeria, there had been antecedent history of mistrust in vaccination by citizens. One of the notable occurrences was the rumour surrounding the content of polio vaccines, which led to boycott of routine immunization activities in some parts of the country nearly two decades ago [19,20].

Nigeria is a multi-ethnic, multi-cultural and multi-religious country with profound differences in the regions of the country [21]. Routine vaccination coverage rates differ across the regions and states of the country including urban-rural differentials [22] These disparities have been adduced to different reasons including mistrust, educational level, political and religious differences [22,23]. Most studies conducted in Nigeria on SARS-COV-2 vaccine uptake and willingness have been at the community, state or among specialized group of people [24–27]. Only few studies have attempted to explore the regional differences in the uptake of the new SARS-COV-2 vaccine with already questionable global acceptance [28–30]. This study was therefore conducted to assess SARS-COV-2 vaccine uptake, determinants of uptake and future intention to have the COVID-19 vaccine among adult Nigerians in the six geopolitical regions. The results will help to identify the regional barriers and inform the design of suitable interventions that can facilitate adoption and adherence to vaccination during public health emergencies in Nigeria.

Methods

Nigeria is the most populous country in Africa. Nigeria has 36 states and a Federal Capital Territory (FCT), Abuja and is distributed into six geopolitical zones (North Central, North East, North West, South East, South-South, and South West). There are six states in each geopolitical zone of Nigeria, except for the northwest, which has seven states, and the southeast, which has five states. As of 2023, Nigeria’s estimated population was projected to be 214 million people [31].

The first case of COVID-19 in Nigeria was identified on February 27, 2020, and by June, 27, 2022, a total of 259,377 have been recorded in all zones of the country. The state with the highest number of confirmed cases of COVID-19 in each region was purposively selected to represent the region. However, Gombe state was selected in the North-Eastern region due to reports of insecurity in other states in the zone (which may have hindered vaccination activities). Consequently, the following states with the number of confirmed COVID-19 cases at the time of survey in each zone were included in the study: Lagos (99,340) in South-West, Federal Capital Territory (28,652) in North-Central, Rivers (16,667) in South-South, Kaduna (11,258) in North-West, Gombe (3,307) in the North-East and Imo (2560) in the South-East [32] (Fig 1).

A cross-sectional survey among adult Nigerians was conducted between May and June 2022. The study enrolled persons aged 18 years and above, of both sexes sampled from the six geopolitical zones in the country. Participants were eligible for enrollment if they had lived in their current residence for at least six months while individuals who were unable to participate in the interview due to ill health were excluded from the survey.

A minimum sample size of 1048 was computed using the prevalence of willingness of COVID-19 vaccine uptake of 58.2% from a previous study among adult Nigerians [29]. In each selected state, the sample selection was based on quota sampling stratified by age, sex, and place of residence. The proportional allocation of respondents to each stratum was based on the analysis of the COVID-19 case-data from the Nigerian Centre for Disease Control (NCDC) Microsite as of May, 2022 [33]_, and this guided the distribution of sample to each of the stratum. Using the quotas as stratified in the microsite, a simple random sampling technique was then used to select the eligible respondents through randomization of phone contacts of individuals residing in the states. These phone contacts were obtained from a registered company’s database.

A "Computer-Assisted Telephone Interview (CATI)" was used to collect data using a structured questionnaire. The questionnaire was pretested among 50 randomly selected adult men and women from the database of phone numbers of residents in Ibadan, Oyo State, a State not part of the survey’s target locations. This pretesting process helped identify, correct errors and ambiguities in the questionnaire and determine the average time required for its administration. The questionnaire was initially developed in English and later translated into Nigeria’s three major languages—Hausa, Igbo, and Yoruba. The final questionnare was then programmed in SurveyCTO software in the local languages, incorporating appropriate routing and conditional logic, and uploaded onto handheld mobile tablets. Fifteen data collectors, each with at least a postgraduate qualification in health-related fields, fluency in the local language, and experience in mobile data collection, were trained to conduct the interviews. The telephone interviews lasted between 20 and 30 minutes. Data were simultaneously entered into mobile tablets as the telephone interview was conducted. Respondents who preferred to defer the time of phone interviews because they were temporarily unavailable were rescheduled after obtaining a new appointment schedule. Each day the data collectors did a preliminary check to ensure that data were successfully uploaded to the central server. To maintain quality control, 110 completed questionnaires were randomly selected, and follow-up calls were conducted by members of the research team to verify responses to specific questions in the survey. At the end of data collection exercise, the complete data were downloaded from the server and exported to Stata version 15 for analysis [34].

STATA version 15 was used for all data analyses. Descriptive statistics were provided as means for continuous variables while categorical variables were expressed as frequencies and percentages. Socio-economic status and Ministry of Health (MOH) trust index was generated as additive indices from six and seven manifest variables respectively. The socio-economic status index was based on household ownership of television, computer, sofa set, refrigerator, and cassette/CD/DVD player and access to electricity. The Ministry of Health trust index was composed of questions on whether the MOH was competent, objective, fair, consistent, sincere, faithful and well-resourced with response options on a 5-point Likert scale ranging from strongly disagree to strongly agree. The socio-economic status was divided into tertiles, while MOH trust index was dichotomized based on the blooms cut-off [35]. Vaccination uptake was defined as those who had received at least one dose of the COVID-19 vaccine, while intention to vaccinate among the unvaccinated was assessed by asking the respondents whether they would be willing to receive the SARS-COV-2 vaccine in future. To assess the factors associated with vaccination uptake and intention to vaccinate, two separate multivariable modified Poisson regressions models with robust error variance were used to determine the prevalence ratios and their corresponding 95% confidence intervals. This was done to obtain objective and unbiased inferences, as the binary outcome variables were not rare. Failing to account for the non-rarity of the binary outcome often leads to an overestimation of risk ratios when using conventional logistic regression [36]. In all the models, only variables with p-value < = 0.2 at bivariate levels were included in the final models. Prevalence ratios were the measure of association with variables with significant test conducted at 5%.

Results

Discussion

Vaccination is a cost-effective public health strategy for preventing and controlling the community spread of communicable diseases like COVID-19. However, despite the efforts put into the rapid development of SARS-CoV-2 vaccines, and ensuring equitable access, uptake remains a major challenge in many countries especially those with large population dynamics like Nigeria. This telephone-based survey was conducted to assess the prevalence of SARS-CoV-2 vaccine uptake among adult Nigerians, its determinants and the intention for future vaccine uptake.

Our study found that less than a third of adult Nigerians were fully vaccinated, though about half of all the respondents had received at least one dose of SARS-CoV-2 vaccine. This prevalence was consistent with findings from a national household survey conducted in Nigeria, which investigated Nigerians’ perceptions of SARS-CoV-2 vaccine uptake. This demonstrates the connection between people’s perceptions and their actual practices [37]. In addition, SARS-CoV-2 vaccine uptake was reported to be higher in the southern region as compared with the Northern regions of the country. The geographical difference in our finding is in keeping with literature on routine immunization activities in the country where Northern states have a lower vaccination coverage [38]. The lower uptake of vaccines has been reoccurring in most northern states, where the inhabitants doubt the potency of vaccines and believe they are deleterious to their well-being. These assumptions are based on past experiences that have occurred in the northern part of the country. One of these is the polio saga that occurred in 2003, where the political and religious leaders of some northern states instructed their populace not to allow their children to be immunized against polio myelitis. These leaders argued that the vaccine could be contaminated with anti-fertility agents (estradiol hormone), HIV, and cancerous agents [19]. The lower uptake of SARS-CoV-2 vaccine in the Northern region is however, worrisome, as COVID-19 disease unlike other vaccine preventable diseases, is a public health emergency and is highly communicable. To achieve herd immunity and halt the transmission of diseases like COVID-19 in future pandemics, it is essential to dispel this hoax.

Worthy to note is that Lagos State had the highest uptake of the vaccine, this is unsurprising as Lagos was the epicenter of the pandemic, had a higher number of respondents and was one of the first states to commence vaccination of the populace thus exposure to vaccines was for a longer period as compared to other states.

Top among the reasons for receiving the vaccine were self-protection which was similar across all regions suggesting the belief in the existence of the SARS-CoV-2 virus and the spread of the disease. This is commendable in view of the several rumors and conspiracy theories on COVID-19 which led to misinformation of the general populace. Nevertheless, respondents in the south south region had the highest proportion who took the vaccine because they felt they were at risk while those in the north western region felt they were not at risk. This finding was, however, similar to a national study which used a similar methodology, where respondents living in the north western region had lower odds of being vaccinated [39,40]. The low uptake of vaccination in the north western region could also be linked to insecurity issues in this region which could have hampered the roll out of vaccination campaigns.

Vaccine uptake was higher among the elderly compared to the younger age adults. This is likely due to higher risk perceptions reported by the elderly population. In addition, when vaccination of the populace commenced, the elderly was given priority thereby, creating earlier awareness among this age group. Also, there were deaths reported among some notable and popular elderly individuals in the country, which could have also impacted on the health seeking behaviour of the elderly. Furthermore, female respondents had higher vaccination rate which could be due to a better health seeking behavior among women in Nigeria as documented by previous studies [18].

Vaccination uptake was also higher among urban residents possibly due to availability and access-related factors. The ease of access plays an important role in vaccination uptake; this was demonstrated in a study conducted across several African countries where structural issues such as the availability of vaccines and distance to the nearest vaccination point were frequently reported in rural areas as barriers to receiving the SARS-CoV-2 vaccine. Access may also explain why the unemployed respondents had lower vaccination rates, as they are more likely to be in the low socio-economic class and reside in rural areas, where accessibility to proper health care services is suboptimal. Accessibility may also have contributed to the higher rates of vaccination uptake among the south west (Lagos) and south south (Rivers) states as they were among the first states to commence vaccination thus may have had better infrastructure, more resources allocated to the rollout, and greater public awareness [41].

However, the south eastern region (Imo) had a much lower vaccine uptake compared to other southern states probably due to security challenges, mandatory weekly “sit at home order” by ethnic militants and proclaimed political undertone of the non- existence of COVID-19 in the south east region [42]. This could have also imparted on the lower intention to receive the SARS-CoV-2 vaccine by inhabitants of the state, highlighting how misinformation and a negative social environment can disrupt public health interventions.

In Nigeria, the COVID-19 pandemic was accompanied by widespread counterproductive rumors and conspiracy theories [29]. These were mainly circulated on the social media and internet hence was mainly among the upper socio-economic class and thus could have influenced their perception of being at risk of COVID-19 and the uptake of the SARS-CoV-2 vaccine. Some Christian religious leaders also openly denied the occurrence of COVID-19 and admonished their followers to do same [43]. These may partly explain why those in the higher socio-economic class and Christians had a lower vaccination rate in this study.

Trust in government institutions is an important precursor for adoption of healthy behaviours especially those communicated through public health messaging. Trust and truthfulness in government represents the satisfaction of people with government performance and the perceived credibility of government recommendations such as vaccine uptake [44,45]. Our findings showed that the trust in ministry of health was a key driver in determining the level of vaccine uptake across the country.

A large proportion of the respondents who had not received the vaccine expressed an intention to uptake the vaccine. This was seen to be highest in the North Western region as compared to other states. The study by Eze et al. (2021), conducted across three regions of the country, also corroborated this finding, revealing that respondents from the Hausa ethnic group and those living in the northern region were more willing to receive the COVID-19 vaccination if recommended by health workers [46]. This may be attributed to the perceived high level of trust in the Ministry of Health in the region, as found in our study, which could influence their intention to receive the vaccine in the future. This is buttressed by previous studies which have demonstrated that trust in government health agencies improve willingness of populace to adhere to government recommendations such as adopting preventive behaviors [47,48]. In addition, the intention to receive the SARS-CoV-2 vaccine has been reported by other surveys in Nigeria to be higher in the northern part of the country [31], this could be related to the exposure to social media rumors and conspiracy theories which was widespread among the more educated southern population which could have imparted on their perception towards the safety of the SARS-CoV-2 vaccine [29].

Conclusion

Low prevalence of SARS-CoV-2 vaccine uptake and high level of intention to vaccine uptake was reported among adult Nigerians. The northern region had the lowest vaccine uptake rates. Key factors influencing increased uptake of SARS-CoV-2 vaccine were older age, female gender, urban residence, employment, Muslim religion, and residence in the southwestern and south southern regions of Nigeria. High trust in ministry of health played a significant role in enhancing vaccine uptake. among adult Nigerians. Concerted efforts need to be made to enlighten the public especially in the Northern region on the safety and need to be vaccinated against COVID-19.

Supporting information

Data Availability

The data is available from the Havard Dataverse with the following details. Bamgboye, Eniola, 2024, "Replication Data for Regional Variation in COVID-19 Vaccine Uptake and Intention in Nigeria: A Computer Assisted Telephone Survey", https://doi.org/10.7910/DVN/OOHXVC, Harvard Dataverse, V1, UNF:6:j3R/I+URXsZ5SxHzf7MxMw== [fileUNF].

Funding Statement

This work was supported in whole, by the Bill & Melinda Gates Foundation [Opportunity ID: INV-019313]. The funding ID:INV-019313 was made available to OF, RW, LT, EB, RN, NC, RA, SK, MS, SB, AA and MD The funding provided was used for the study implementation. The views, opinions, and content of this publication are those of the authors and do not necessarily reflect the views, opinions, or policies of the Bill and Melinda Gates Foundation.