COVID vaccines reduced the potential global death toll during the pandemic by almost two-thirds in their first year, saving an estimated 19.8 million lives, according to a mathematical modeling study yesterday in The Lancet Infectious Diseases.
An additional 600,000 lives could have been spared if a World Health Organization (WHO) goal of vaccinating 40% of the population of every country by the end of 2021 had been met, the authors of the study say.
Vaccination cut deaths an estimated 63%
To estimate the impact of vaccination worldwide, researchers from Imperial College London used a proven model of COVID-19 spread using country-level data for official COVID deaths that occurred from Dec 8, 2020—when vaccines were first rolled out—to Dec 8, 2021. They conducted a separate analysis of expected excess deaths to account for under-reporting of COVID-19 deaths during the study period.
They then compared the two analyses with a scenario that didn't include vaccination to arrive at their estimates. The data spanned 185 countries and territories.
The model accounted for variation in vaccination rates between countries, as well as differences in vaccine efficacy in each country based on efficacy data for various vaccines. They excluded China from their analysis because its strict lockdowns and large population would have skewed the results.
The scientists estimated that 18.1 million deaths would have occurred during the study period without vaccination. Of those, the model estimated that vaccination prevented 14.4 million deaths, or 79%. When they accounted for under-reporting, however, they found that COVID vaccination prevented an estimated 19.8 million deaths out of a total of 31.4 million potential deaths that would have occurred without vaccination—a reduction of 63%.
Of those prevented deaths, they estimated that 15.5 million (78.2%) were due to direct vaccine effects. The remainder were due to indirect vaccine affects through reduced disease transmission and lower burden on healthcare systems.
The authors found that high- and upper-middle-income countries accounted for the greatest number of prevented deaths (12.2 million), highlighting inequalities in vaccine access. And they estimated that an additional 599,300 deaths could have been averted if the WHO's target of vaccinating 40% of the population in every country by the end of 2021 had been met.