The impact of national income and vaccine hesitancy on country-level COVID-19 vaccine uptake

Abstract

Background: The rapid development and rollout of COVID-19 vaccines helped reduce the pandemic's mortality burden. The vaccine rollout, however, has been uneven; it is well known that vaccination rates tend to be lower in lower income countries. Vaccine uptake, however, ultimately depends on the willingness of individuals to get vaccinated. If vaccine confidence is low, then uptake will be low, regardless of country income level. We investigated the impact on country-level COVID-19 vaccination rates of both national income and vaccine hesitancy.

Methods: We estimated a linear regression model of COVID-19 vaccine uptake across 145 countries; this cross-sectional model was estimated at each of four time points: 6, 12, 18, and 24 months after the onset of global vaccine distribution. Vaccine uptake reflects the percentage of the population that had completed their primary vaccination series at the time point. Covariates include per capita GDP, an estimate of the percentage of country residents who strongly disagreed that vaccines are safe, and a variety of control variables. Next, we estimated these models of vaccine uptake by country income (countries below, and above the international median per capita GDP) to examine whether the impact of vaccine hesitancy varies by country income.

Results: We find that GDP per capita has a pronounced impact on vaccine uptake at 6 months after global rollout. After controlling for other factors, there was a 22 percentage point difference in vaccination rates between the top 20% and the bottom 20% of countries ranked by per capita GDP; this difference grew to 38% by 12 months. The deleterious impact of distrust of vaccine safety on vaccine uptake became apparent by 12 months and then increased over time. At 24 months, there was a 17% difference in vaccination rates between the top 20% and the bottom 20% of countries ranked by distrust. The income stratified models reveal that the deleterious impact of vaccine distrust on vaccine uptake at 12 and 24 months is particularly evident in lower income countries.

Conclusions: Our study highlights the important role of both national income and vaccine hesitancy in determining COVID-19 vaccine uptake globally. There is a need to increase the supply and distribution of pandemic vaccines to lower-income countries, and to take measures to improve vaccine confidence in these countries.

Fig 1. Vaccine uptake at December 31, 2022, by % of population that strongly disagrees that vaccines are safe.

Note: Each panel highlights observations on countries in a different income quintile and fits a spline curve to these observations. Countries in which more than 7% of the population strongly disagrees that vaccines are safe are labelled. FRA = France, HRV = Croatia, SRB = Serbia, UKR = Ukraine, ARM = Armenia, AZE = Azerbaijan, BIH = Bosnia and Herzegovina, KAZ = Kazakhstan, MKD = North Macedonia, TGO = Togo.

Fig 2. Estimated parameters and 95% confidence intervals from regression model of percentage of population that completed primary COVID-19 vaccinations as of June 30, 2021, Dec. 31, 2021, June 30, 2022, Dec. 31, 2022, respectively.

Fig 3. Estimated parameters and 95% confidence intervals from regression model of percentage of population that completed primary COVID-19 vaccinations as of June 30, 2021, Dec. 31, 2021, June 30, 2022, Dec. 31, 2022, respectively.

Population size, mean years of schooling, and the elderly share of the population covariates removed from model.

Fig 4. Estimated parameters and 95% confidence intervals from regression model of percentage of population that completed primary COVID-19 vaccinations as of June 30, 2021, Dec. 31, 2021, June 30, 2022, Dec. 31, 2022, respectively.

Population size, mean years of schooling, and the elderly share of the population covariates removed from model. Expected years of schooling included in model.

Fig 5. Estimated parameters and 95% confidence intervals from regression model of percentage of population that completed primary COVID-19 vaccinations as of Dec. 31, 2021, and Dec. 31, 2022, respectively.

Estimates provided separately for countries in the bottom and top 50% of countries by GDP per capita. The parameters for the log of per capita GDP, vaccine confidence, and expected years of schooling covariates reflect the impact of a one percent (proportional) increase in the covariate on the vaccinated share of the population.