How the population worldwide is reacting to the COVID-19 vaccines: a systematic review on hesitancy

Background High rates of vaccination are worldwide required to establish a herd immunity stopping the current COVID-19 pandemic evolution. Vaccine hesitancy is a major barrier in achieving herd immunity across different populations. This study sought to conduct a systematic review of the current literature regarding attitudes and hesitancy to receiving COVID-19 vaccination worldwide. Methods A systematic literature search was performed in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Multiple databases were searched, namely PubMed and Web of Science, on February 24th, 2021 using a set of developed keywords. Inclusion criteria included the study to be 1) conducted in English; 2) investigated attitudes, hesitancy, and/or barriers to COVID-19 vaccine acceptability among a given population; 3) utilized validated measurements techniques; 4) have the full text paper available and 5) be peer-reviewed prior to final publication. The Newcastle Ottawa (NOS) scale for cross sectional studies was used to assess the quality of the studies. Results 73 studies were included in qualitative synthesis. Overall, vaccine acceptance rates ranged from 23.6% in Kuwait to 94.3% in Malaysia and Nepal. A variety of different factors contributed to increased hesitancy, some of which included having negative perception of vaccine efficacy, safety, convenience and price. Some of the consistent socio-demographic groups that were identified to be associated with increased hesitancy included: women, younger participants, less educated, with lower income, with no insurance, living in the rural area and self-identified as a racial/ethnic minority. Conclusions Vaccine hesitancy rates against COVID-19 vaccine ranged widely among across different populations. Identifying the factors that interplay and result in high hesitancy rates among a population can allow formulating a directed intervention to increase their vaccination uptake rates. Key messages It is necessary to understand the factors that contribute to the COVID-19 vaccine hesitancy. It is important to inform policy-makers and formulate direct intervention measures that will successfully handle the pandemic.