COVID vaccines reduced the potential global number of deaths during the pandemic by nearly two-thirds in their first year, saving approximately 19.8 million lives, according to a mathematical modeling study yesterday in The Lancet Infectious Diseases.
An additional 600,000 lives could be saved if the goal of the World Health Organization (WHO) to vaccinate 40% of each country’s population by the end of 2021 was met, the study’s authors say.
Vaccination reduces deaths by about 63%
To assess the impact of vaccination worldwide, researchers at Imperial College London used a proven pattern of COVID-19 prevalence, using country-level data on official COVID deaths since 8 December 2020 – when the vaccines were introduced for for the first time, by December 8, 2021. They conducted a separate analysis of expected over-deaths to account for the under-reporting of COVID-19 deaths during the study period.
They then compared the two analyzes with a non-vaccination scenario to arrive at their assessments. The data cover 185 countries and territories.
The model takes into account variations in vaccination levels between countries, as well as differences in vaccine efficacy in each country based on efficacy data for different vaccines. They excluded China from their analysis because its strict blockades and large populations would skew the results.
The researchers estimated that 18.1 million deaths would occur during the study period without vaccination. Of these, the model estimates that vaccination prevented 14.4 million deaths, or 79%. However, when they reported insufficient reporting, they found that vaccination against COVID prevented approximately 19.8 million deaths out of a total of 31.4 million potential deaths that would have occurred without vaccination, a 63% reduction.
Of these prevented deaths, they estimated that 15.5 million (78.2%) were due to the direct effects of the vaccine. The rest are due to the indirect effects of vaccines through reduced disease transmission and lower burden on health systems.
The authors found that high- and higher-middle-income countries accounted for the highest number of prevented deaths (12.2 million), highlighting inequalities in access to vaccines. And they estimated that an additional 599,300 deaths could have been avoided if the WHO’s goal of vaccinating 40% of the population in each country by the end of 2021 had been met.
The authors conclude: “The results of this analysis still provide a comprehensive and in-depth assessment of the impact of COVID-19 vaccination, revealing the significant impact that vaccines have had and the millions of lives likely to be saved in the first year. could have been saved if vaccines had been distributed more quickly in many parts of the world and if the absorption of vaccines could have been stepped up worldwide. “
“More could have been done”
Lead author Oliver Watson, PhD, said in a statement to the Lancet: “Our findings offer the most complete assessment to date of the remarkable global impact that vaccination has had on the COVID-19 pandemic. Of the nearly 20 million deaths estimated to have been prevented in the first year after the introduction of the vaccines, almost 7.5 million deaths were prevented in the countries covered by the COVID-19 Vaccine Access Initiative (COVAX).
“But more could have been done. If the goals set by the WHO were achieved, we believe approximately 1 in 5 of the life expectancy lost due to COVID-19 in low-income countries could be prevented. “
Co-author Gregory Barnsley, MSc, said: “Quantifying the impact of vaccination worldwide is a challenge as access to vaccines varies from country to country, as does our understanding of which variants of COVID-19 are circulating. with very limited genetic sequence data available for many countries. It is also not possible to directly measure how many deaths would occur without vaccinations. Mathematical modeling offers a useful tool for estimating alternative scenarios that we cannot directly observe in real life. “
Commenting on the study in the same journal, Dr. Chad Wells and Dr. Alison Galvani of the Center for Modeling and Analysis of Infectious Diseases at Yale highlighted various obstacles facing countries in vaccinating their populations.
They noted that the Democratic Republic of the Congo had to return more than 1.3 million donated doses and that more than 114,000 doses had expired due to the inability to maintain refrigerated chain storage. They also highlight the fluctuations in vaccines caused by widespread misinformation in Nigeria and the United States and the low uptake of vaccines due to the violence and unrest in Yemen and Ukraine.
“Saving more than 19 million lives through the unprecedented speed of developing and deploying vaccines against COVID-19 is an outstanding global health feat,” Wales and Galvani wrote.
“However, millions of additional lives could be saved through a fairer distribution of vaccines. The most effective approaches to promoting vaccine coverage worldwide are multifaceted … A sustained collective response is both a pragmatic and an ethical imperative. ”
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