Global COVID-19 Vaccine Acceptance Rate: Systematic Review and Meta-Analysis

Abstract

Background: A vaccine against COVID-19 is a vital tool in managing the current pandemic. It is becoming evident that an effective vaccine would be required to control COVID-19. Effective use of vaccines is important in reducing the pandemic and paving the way for an acceptable exit strategy. Therefore, the current review aimed to determine the global acceptance rate of the COVID-19 vaccine that is necessary for better management of the COVID-19 pandemic.

Methods: This review was conducted under the Preferred Reporting Items for Systematic Reviews and Meta-Analysis protocol and considered the studies conducted on the acceptance and / or hesitancy of the COVID-19 vaccine around the world, and written in English language. Articles were searched using electronic databases including PubMed / MEDLINE, Scopus /Science Direct, Web of Science, Embase, CINAHL, and Google Scholars from February to March 2021 (for articles conducted in 2020) and May to June 2022 (for articles conducted in 2021). The quality of the study was assessed using the Joanna Briggs Institute Critical Assessment tool for prevalence studies to determine the relevance of each included article to the study.

Results: A total of 6021 articles were searched through electronic databases, of which 68 articles were included in the systematic review and meta-analysis. The global pooled acceptance rate of the COVID-19 vaccine was found to be 64.9% [95% CI of 60.5 to 69.0%]. Based on the subgroup analysis of the acceptance rate of the COVID-19 vaccine by WHO region, the countries where the study was conducted, occupation, and survey period was 60.8% [95% CI: 56.3, 65.2%], 61.9% [95% CI: 61.3, 62.4%], 81.6% [95% CI: 79.7, 83, 2%] and 64.5% [95% CI: 60.3, 68.5%], respectively.

Conclusions: This review found the variation in the level of COVID-19 vaccine acceptance rate across the world. The study found that the overall prevalence of COVID-19 vaccine acceptance was 64.9%. This finding indicated that even if the COVID-19 vaccine is developed, the issue of accepting or taking the developed vaccine and managing the pandemic may be difficult.

1. Introduction

The Corona virus disease 2019 (COVID-19) has spread drastically throughout the world, since the first case of COVID-19 disease was reported in Wuhan, China [1], and has rapidly become a major public health concern [2]. Vaccination has played a fundamental role in global public health, leading to increased life expectancy[3] and is one of the most cost-effective ways of avoiding the disease and currently prevents between two and three million deaths per year [4]. It is becoming evident that an effective vaccine would be required to control COVID-19 [7]. Effective use of vaccines is necessary to reduce the social and economic burden and to prepare the way for an acceptable exit strategy from the COVID-19 pandemic[8]. Vaccination hesitancy and anti-vaccination movements are increasing and need critical attention [9-11]. Similarly, a vaccine against COVID-19 is a vital tool in the management of the COVID-19 pandemic [5, 6]. 

Currently, vaccination rates have fallen and public confidence in vaccines has been inconsistent [6, 13] and various studies reported a declining level of willingness to accept the COVID-19 vaccine[14]. Globally, the intention of being vaccinated against the COVID-19 pandemic is declining from time to time [8]. According to the World Health Organization (WHO), vaccine hesitancy has become an emerging global issue and has been identified as one of the top ten threats to global health in 2019 [12]. 

Although vaccines are developed against COVID-19, many factors compromise the acceptance of the vaccine against COVID-19 and become a public concern [13, 15]. Furthermore, transparent and effective communication efforts are essential to reduce misinformation and vaccine hesitancy and build trust to ensure adequate vaccination coverage will be achieved [8].

Previously, several studies have been conducted and many literatures have been published to capture and address many issues regarding the COVID-19 pandemic. However, to our knowledge, no adequate studies have investigated that provide the global pooled acceptance or hesitancy rate of the COVID-19 vaccine. Thus, the current review aimed to determine the acceptance rate of the COVID-19 vaccine across the world, which is necessary to understand the acceptance or hesitancy of the vaccine in different contexts and can be input for others pandemics also.

2. Materials And Methods

This systematic review was conducted under the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines [16].

2.1 Eligibility criteria

Studies that met the following inclusion criteria were included in the systematic review and meta-analysis. The inclusion criteria considered in this review include: -

• Study Population: All populations regardless of their age, occupation, ethnicity, gender, etc.
• Outcomes: articles aimed to determine the hesitancy and/or acceptance of COVID-19 vaccines that provided a quantitative outcome. 
• Language: Studies written in English.
• Types of articles:   Peer-reviewed full text, original, and published articles.
• Publication year: Studies published since after the emergency of COVID-19 to the study period (March 2020 to June 2022).
• Study regions / locations: Not specified (no limitation).

However, articles not freely available, not peer reviewed manuscripts or preprints; editorial papers; reports; short communications; review articles; the article did not provide outcome of the interest (COVID-19 acceptance rate or prevalence).

2.2 Information sources and search strategy

Article searches were performed using key terms of review; COVID-19, vaccine hesitancy, vaccine acceptance and intention to vaccine, and Medical Subject Headings (MeSH) in combination with Boolean logic operators (“AND”, “OR”, and “NOT”) through various electronic databases from PubMed/Medline, Scopus or Science direct, Web of Science, Embase, CINAHL, and Google scholars. Furthermore, the articles were searched directly from Google. References within eligible papers were screened for additional articles. There was no specific date for the search of the articles for each database. For example, the articles were searched from the first February to March 29, 2021 and May to June 2022 on PubMed, Scopus, Embase, and Google Scholars, while the search on Web of Science, CINAHL, and Google was made from 15 February to 31 March 2021.

The Embase search strategy was made as follows: (1) COVID 19 ' OR ‘COVID 19’/exp OR Coronavirus OR coronavirus/exp OR ‘2019 nCOV’ OR ‘2019 nCOV’/exp OR ‘severe acute respiratory syndrome coronavirus 2' / exp OR 'SARS-COV-2' OR 'SARS-COV 2/exp; (2) Vaccine OR *vaccine/exp* OR *Vaccination* OR *Vaccination/exp OR Immunization OR Immunization/exp; (3) acceptance OR acceptance /exp; OR ‘hesitance’ OR ‘hesitance/exp’ OR ‘refusal OR ‘refusal/exp’;(4) 1 AND 2 AND 3. 

The PubMed search strategy was performed as follows: (1) 'Corona virus' [MeSH Terms] OR 'Corona virus' [All Fields] OR 'Corona virus' [All Fields] OR 'COVID-19' [All Fields] OR 'SARS-2' [All Fields] OR 'Severe acute respiratory syndrome corona virus 2' [All Fields] OR '2019 nCOV' [All Fields] OR 'SARS COV-2' [All Fields] OR 'Corona virus' [All Fields] AND; (2) 'Vaccines' [MeSH Terms] OR 'Vaccine' [All Fields] OR 'Vaccinations' [All Fields] OR 'Vaccines' [All Fields] OR 'Vaccines' [All Fields]; (3) “acceptance” [MeSH Terms] OR “hesitancy” [All Fields] OR “refusal” [All Fields] OR “accepted” [All Fields] OR “willingness to accept” [All Fields]; (4) 1 AND 2 AND 3.

The Scopus and Web of Science search strategy was made using a combination of keywords and Boolean functions: (1) (*COVID-19 * OR *Corona virus* OR *nCOV * OR *SARS COV-2*; (2) Vaccines *OR *Vaccination *OR *vaccinates*); (3) (*acceptance*OR *hesitancy* OR *refusal* OR accepted *OR *willingness to accept*; (4) 1 AND 2 AND 3) or 1 AND (2 OR 3) 

The search strategy from Google Scholars and Google was done using keywords such as (Corona virus, nCOV, SARS, COV-2, COVID-19) AND (Vaccines OR Vaccination OR Vaccinates); (3) (acceptance OR hesitancy OR refusal OR accepted OR willingness to accept; (4) 1 AND 2 AND 3.

Articles published from March 2021 to June 2022 were searched from the included electronic databases according to their own searching strategies. The search was carried out from the first February 2021 to the last March 2021 and from May to June 2022. 

2.3 Study Selection

The study selection process was performed using the PRISMA flow chart, indicating the number of articles included in the review and articles excluded from the study with the reasons. Following the search for articles through selected electronic databases, duplicate studies were removed using the ENDNOTE software version X5 (Thomson Reuters, USA). After removing duplicate articles, the authors (DAM, YAA, and YMD) independently selected the articles based on the titles and abstracts applying the inclusion criteria. 

Furthermore, the full text of the relevant articles further read in detail and the inclusion criteria independently evaluated by the authors. Any disagreements made with respect to the inclusion of studies were resolved by consensus after discussion. Finally, studies that met the criteria were included in the systematic review and meta-analysis.

1. Data Extraction 

The data were extracted by the authors (DAM, YAA, and YMD) independently. Predetermined tabular format consisting of study characteristics including publication year, survey period, country where the study was conducted, number of respondents, and outcome (COVID-19 vaccine acceptance/hesitancy rate using Microsoft Excel, 2016). Any disagreement made between the authors was resolved through discussion after the same procedures were repeated.

1. Data Quality Assessment/Management

The selected articles were subjected to a rigorous independent assessment using a standardized critical assessment tool, Joanna Briggs Institute (JBI) Critical Assessment Tools for prevalence studies [17]. The evaluation tools have the following nine evaluation criteria/ parameters; (1) appropriate sampling frame; (2) proper sampling technique; (3) adequate sample size; (4) description of the study subject and setting description; (5) sufficient data analysis; (6) use of valid methods for identifying conditions; (7) valid measurement for all participants; (8) use of appropriate statistical analysis and (9) adequate response rate.

The authors ((DAM, YAA, and YMD)) assessed the quality of the included studies. Based on the items in the above appraisal tool, the articles were classified as high quality (80% and above), moderate (60-80% score), and low quality (<60% score). Articles with a score >60% were included in the review, while those with low quality were excluded from the study Finally, the disagreements made among the authors were resolved by discussion and repeating the same procedures. 

2.5 Outcome Measures

The term 'vaccine hesitancy' refers to 'delay in acceptance or refusal of vaccines despite the availability of vaccine services [6, 18, 19]'.   In this review, for articles that did not provide general acceptance of the vaccine among study participants, the prevalence of vaccine acceptance was calculated based on the response of the participants. The participant responded strongly agree, agree, completely agree, accept, all, accept, some accept, and yes to the questions were considered as accepted. Finally, the prevalence was calculated based on the frequency of responses and the total number of respondents. The same principle was applied to the studies that reported the results based on the Likert scale and others (Figure 1). 

2.6 Statistical Procedures and Data Analysis

The pooled prevalence / acceptance rate of the COVID-19 vaccine was performed using Comprehensive Meta-Analysis (CMA) version 3.0 statistical software. Forest plots and random-effects models were used to determine and visualize the pooled acceptance rate of the COVID-19 vaccine. The Cochran Q test (Q) and I Squared test (I² statistics) were used to evaluate the heterogeneity between the included articles.  Then, heterogeneity was classified into low (I² index < 25%), medium (I² index ranging from 25–75%), and high heterogeneity (I² index > 75%). The random-effects model was used to analyze the data.  Furthermore, subgroup analysis was performed based on the year of publication, survey period (when the study was conducted), and study area. Publication bias between the included studies was evaluated using funnel plots (Figure 2). 

A p-value of < 0.05 was considered as evidence of publication bias. Sensitivity analysis was employed to determine differences in pooled effects by dropping studies that were found to influence the summary estimates, including extreme sample size and outcomes.

3. Results

3.1 Study Selection

A total of 6021 short communications, and editorial articles were searched through electronic databases from PubMed/MEDLINE, Scopus/Science direct, Web of Science, Embase, CINAHL, and Google scholars. The search for the articles was done from February to March 2021 (For articles conducted in 2020) and May to June 2022 (for articles conducted in 2021). After the search for the articles, 1310 duplicate articles were excluded. Furthermore, 2201 articles were excluded after initial selection based on abstracts and titles. Furthermore, 599 articles were excluded after eligibility for full text articles (n = 601). Finally, a total of 68 articles were included in the systematic review and meta-analysis (Figure 3).

3.2 Characteristics of the included articles

In this review, a total of 143,111 study participants were included in 68 original full-text articles throughout the world and published from 2020 to 2022. The included articles were conducted in 38 countries of the world (Figure 3).

Additionally, three articles were conducted in each Malaysia [44-46] and Kuwait [28, 47]. Two articles conducted in each Qatar[48, 49],  Italy[15, 50],  Jordan [28, 51], Bangladesh [52, 53], Ethiopia [54, 55], Taiwan [56, 57] and Germany [58, 59]. However, only one article was conducted in each of the following countries;  Republic of Congo [60], Japan [61], Poland [10], Cameroon[7], Israel [62], Mexico [63], Malta[64], Scotland[6], Indonesia [65], England [66], South Korea [67], Iran [68], Nigeria [69], Tunisia [70], Netherlands [71], Thailand  [72], Vietnam [73], United Arab Emirates  [74], Botswana [75], Sudan [76], Czechia [77], Uganda [78], France [79], and in Egypt  [80].

The included studies were cross-sectional studies with a sample size ranging from 123 [64] to 23,582 [32] study participants. In general, the overall global acceptance rate of the COVID-19 vaccine, regardless of occupation, was 63.4% and ranged from 15.4% [7] to 95.6% [23] (Table 1).

Table 1: Overall characteristics of the articles included in the systematic review and meta-analysis, 2022.

Keys: HCWs: Healthcare Workers

3.3 COVID-19 Vaccine Acceptance

The meta-analysis was performed using Comprehensive Meta-Analysis (CMA) Version 3 statistical software determine the global pooled prevalence / acceptance rate and the hesitancy rate of the COVID-19 vaccine.

3.3.1 The Overall Pooled Prevalence /Rate of COVID-19 Vaccine Acceptance

The pooled prevalence rate for the acceptance of the COVID-19 vaccine was found to be 64.9% [95% CI of 60.5 to 69.0%]; I² = 99.57% with a p-value of <0.001 (Figure 4). 

3.3.2 Subgroup analysis of the pooled prevalence rate of COVID-19 vaccine acceptance 

Based on the subgroup analysis that was employed based on the World Health Organization Region, the overall pooled prevalence rate of acceptance of the COVID-19 vaccine was 60.8% [95% CI: 56.3, 65.2%]. The lowest prevalence of acceptance rate was reported in the Eastern Mediterranean Region accounting for 60.8% [95% CI: 43.4, 57.2%], whereas the highest prevalence was reported in South East Asian Region which accounted for 81.0% [95% CI: 59.9, 92.4%] (Figure 5).

Based on the countries where the study was conducted, the lowest prevalence of COVID-19 vaccine acceptance rate was reported in Cameroon [15.4% (95% CI: 14.0, 16.9] followed by the highest prevalence [95.6% (95% CI: 93.8, 96.9%] of COVID-19 vaccine acceptance was reported in Thailand followed by Indonesia [93.3% (95% CI: 91.8, 94.5%] (Figure 6). 

Based on the study participants, the highest COVID-19 vaccine acceptance rate was reported among the healthcare workers prevalence [71.4% (95% CI: 59.9, 80.7%] followed by students 64.7% (95% CI: 32.6, 89.2%]. The lowest prevalence of COVID-19 vaccine acceptance rate was reported among patients [51.8% (95% CI: 36.8, 66.6%] (Table 7)

Based on the survey period, the pooled prevalence of the COVID-19 vaccine acceptance rate was 64.5% [95% CI: 60.3, 68.5%]. Relatively, the lowest prevalence [57.9% (95% CI: 49.2, 66.2%] of vaccine acceptance was reported from September to November 2020, followed by [60.1% (95% CI: 40.5, 76.9%], whereas the highest prevalence [81.0% (95% CI: 57.3, 93.1%] was reported between September to November 2021 (Figure 8).

3.4 Publication bias

3.4.1 Sensitivity analysis

Sensitivity analysis was performed by removing low outcome, high outcome, and small sample size. However, the sensitivity analysis did not show a substantial change in the prevalence of COVID- 19 acceptance compared to the pooled prevalence without sensitivity analysis [61.1% (95% CI 53.8 to 67.9%)] (Table 2).

Table 2: Results of sensitivity analysis for COVID-19 vaccine acceptance rate, 2022.

4 Discussion

We conducted a systematic review and meta-analysis of data from 68 studies that included 143,111 study participants and found a pooled prevalence of vaccine acceptance of 64.9% [95% CI of 60.5 to 69.0%]. Some articles were conducted by the same authors across various countries. Because of high heterogeneity, the sensitivity analysis was used to assess the cause of high heterogeneity and found no substantial change in the prevalence of COVID-19 vaccine acceptance.

The utility of the vaccine to control COVID-19 pandemics depends on the acceptance of the vaccine [82]. Currently, vaccine hesitancy represents a serious threat to global health. Similarly, the current review found that the worldwide pooled prevalence of COVID-19 vaccine acceptance was 64.9% [95% CI of 60.5 to 69.0%], which was lower than the finding of the global survey reported 71.5% COVID-19 acceptance rate [83]. The possible reason for the disparity in the prevalence estimate could be variation in the population studied or the survey period. The former study mainly conducted in the specific study period, whereas the present study finding depends on the study conducted in the emergency of COVID-19 in this study period. 

 The lowest prevalence of COVID-19 vaccine acceptance rate was reported in the Cameroon [15.4% (95% CI: 14.0, 16.9] while the highest prevalence [95.6% (95% CI: 93.8, 96.9%] of COVID-19 vaccine acceptance was reported in Thailand followed by Indonesia [93.3% (95% CI: 91.8, 94.5%]. The variation may be as a result of variation in sources of information and types of study participants. Because, the study conducted in Thailand involved healthcare workers, whereas the study conducted in Cameroon involved the general population as the study participants. 

Furthermore, the review found a slight difference in the pooled prevalence of COVID-19 vaccine acceptance rate among the studies conducted in United State [60.4% (95% CI 56.6, 64.1%)], the United Arab Emirates [58.0% (95% CI 53.7, 62.2%)], and Taiwan [64.6% (95% CI 41.0, 82.7%)], and Qatar [60.6% (95% CI 59.6, 61.7%)]. 

Similarly, there was slightly different in the prevalence of COVID-19 acceptance rate among the studies conducted in United Kingdom [71% (95% CI: 51.3, 85.1%)], in South Korea [70.8% (95% CI: 67.3, 74.0%)], Netherland [69.6% (95% CI: 62.0,76.2%)] , Italy [69.2% (95% CI: 30.3, 92.1%)], Iran [69.0% (95% CI: 67.6, 70.3%)], France [71.3% (95% CI: 65.2, 76.7%)]and in Czechia [70.2% (95% CI: 65.3, 74.7%)]. However, in some countries there was a lower prevalence, such as Cameroon and Jordan reported 15.4 and 32%, respectively. In general, the variation in the estimate of the vaccine acceptance rate may be due to the difference in the information and sociodemographic characteristics of the study participants (Figure 9). 

Based on World Health Organization Region, the overall pooled prevalence rate of acceptance of the COVID-19 vaccine was 60.8% [95% CI: 56.3, 65.2%] that was slightly lower than the finding without subgroup analysis. The lowest COVID-19 vaccine acceptance rate was reported in the Eastern Mediterranean Region accounting for 60.8% [95% CI: 43.4, 57.2%], followed by Western pacific [74.7% CI: 65.2, 82.3%] and American region (66.4%: CI: 59.4, 82.3%). However, the highest prevalence was reported in South East Asian Region which accounted for 81.0% [95% CI: 59.9, 92.4%]. The variation in vaccine acceptance rate may be related to the level of risk perception, study participants involved, and access to information (Figure 10). 

Based on the survey period, the COVID-19 acceptance rate was 76.5%, 60.1%, 57.9%, 61.9%, 72.6%, 68.5% and 81.0% for the articles conducted from March to May 2020, June to August 2020, September to November 2020, December 2020 to February 20211, March to May 2021, June to August 2021 and September to November 2021, respectively. This indicates that there is a decline in COVID-19 vaccine acceptance rate from March to November 2020. The current study is supported by various studies (country or region specific) that reported a decline in willingness to accept the COVID-19 vaccine [6, 13, 14]. Similarly, this finding was in line with the finding of another study that reported a decrease in the acceptance rate of the COVID-19 vaccine from more than 70.0% in March to less than 50% in October [84]. However, there was an increasing in COVID-19 vaccine acceptance rate from December 2020 to November 2021. The increasing in COVID-19 vaccine acceptance rate could be related to the increasing in awareness, change in risk perception, and the round of vaccines given across the world. The variation in the vaccine acceptance rate based on the survey period is indicated in the figure below (Figure 11).

Limitations

There was an unequal distribution of the studies conducted across the world. Furthermore, the acceptance rates of the COVID-19 vaccine in many countries of the world were not included because of the lack of studies that met the eligibility criteria. Similarly, as the result of variation in the unit of measurements/statistical analysis employed for data analysis, we could not able to determine the factors associated to COVID-19 acceptance rate. Furthermore, cross-sectional studies were included and causal relationships between the acceptance rate of the COVID-19 vaccine and the determinant factors cannot be established.

Conclusion

This review found a decline in the acceptance rate of the COVID-19 vaccine in 2020 and relatively increasing I acceptance in 2021. The maximum of 8 in 10 people accepted COVID-19 vaccine that needs critical attention to manage the COVID-19 pandemic. This finding indicated that even if the COVID-19 vaccine is developed, the issue of accepting or taking the developed vaccine and managing the pandemic will be difficult unless appropriate measures are taken when it is necessary. Furthermore, we recommend further studies, particularly on the determinants or factors that lead to hesitancy.

Abbreviations

CMA: Comprehensive Meta-Analysis; COVID-19: Coronavirus disease, 2019; JBI: Joanna Briggs Institute; Preferred Reporting Items for Systematic Review and Meta-Analysis; WHO: World Health Organization; MeSH: Medical Subject Heading.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Data Availability

All data are included in this study.

Competing Interests

The authors declare that there is no competing interest in this work.

Funding

Not applicable.

Authors’ Contributions

DA. Mengistu conceived the idea and had a major role in the review, extraction, and analysis of the data, writing, drafting and editing of the manuscript. YMD and YAA. Demmu has contributed to data extraction, analysis, and editing. Finally, the authors (DAM, YAA, and YMD) read and approved the final version of the manuscript to be published and agreed on all aspects of this work.

Acknowledgments 

The authors extend their deepest thanks to Haramaya University, Department of Environmental Health staff, for providing their constructive support. 

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