Factors associated with COVID-19 vaccination rates in countries with different income levels: a panel analysis

Vaccines against coronavirus disease (COVID-19) are being developed and supplied at an unprecedented rate. However, disparities in income levels among countries has influenced the supply and vaccination rate. This imbalance poses a potential risk factor, especially if vaccine-resistant variants emerge and the pandemic persists. To effectively combat a global pandemic such as COVID-19, understanding the key factors that influence vaccination rates worldwide is essential. This study utilizes cross-country panel regression to examine the factors associated with vaccination rates in countries at different income levels.

We analyzed weekly vaccination rates in relation to several COVID-related variables, including government suppression policies, vaccination coverage, and search trends from Google Trends. The data consistently spanned from March 2021 to February 2022. Random-effects panel regression models were employed to identify factors linked to weekly vaccination rates by income level. Independent variables included disease status, country characteristics, policy variables, and search trends.

Significant disparities in weekly vaccination rates were observed between income-level groups. High-income countries experienced considerable fluctuations during outbreaks, whereas, low- and lower-middle-income countries demonstrated steady increase over time. The random-effects model, stratified by income level, showed that the vaccination coverage and search trend for "COVID-19 vaccine" were commonly associated with higher vaccination rates across all income groups. However, other factors varied based on income level, and gross domestic product per capita was not significant in the regression based on income level.

Vaccination rate and their associated factors differed across income levels. There is no universal strategy for boosting vaccination rates during a pandemic. Consequently, country specific approaches, including promotional programs to raise awareness and interest in vaccination, are essential for preparing for future pandemics.