Thanks to vaccinations against SARS-CoV-2 in the period 2020-2024 2.533 million deaths were prevented at global level, one death was avoided for every 5,400 doses of vaccine administered. The 82% of the lives saved by vaccines involved people vaccinated before encountering the virus, 57% during the Omicron period, and 90% involved people aged 60 years and older. In all, vaccines have saved 14.8 million years of life (one year of life saved for 900 doses of vaccine administered).
These are some of the data released in an unprecedented study published in the journal Jama Health Forum and coordinated by Prof. Stefania Boccia, Stefania Boccia, Professor of General and Applied Hygiene at Università Cattolica, with contributions from Dr. Angelo Maria Pezzullo, Researcher in General and Applied Hygiene, and Dr. Antonio Cristiano, a medical resident in Hygiene and Preventive Medicine. The two researchers spent a period at Stanford University, collaborating directly with the group of Professor John P.A. Ioannidis, director of the Meta-Research Innovation Center (METRICS), in the context of the project "European network staff eXchange for integrAting precision health in the health Care sysTems- ExACT" funded by the European Research Excellence Programme RISE project-Marie Slodowska Curie and coordinated by Professor Stefania Boccia.
Professor Boccia and Dr. Pezzullo explain: "Before ours, several studies tried to estimate lives saved by vaccines with different models and in different periods or parts of the world, but this one is the most comprehensive because it is based on worldwide data, it also covers the Omicron period, it also calculates the number of years of life that was saved, and it is based on fewer assumptions about the pandemic trend."
THE STUDY
The experts studied worldwide population data, applying a series of statistical methods to figure out who among the people who became ill with COVID did either before or after getting vaccinated, before or after Omicron period, and how many of them died (and at what age). 'We compared this data with the estimated data modeled in the absence of COVID vaccination and were then able to calculate the numbers of people who were saved by COVID vaccines and the years of life gained as a result of them,' Dr Pezzullo explains.
It also turned out that most of the saved years of life (76%) involved people over 60 years of age, but residents in long-term care facilities contributed only with 2% of the total number. Children and adolescents (0.01% of lives saved and 0.1% of life years saved) and young adults aged 20-29 (0.07% of lives saved and 0.3% of life years saved) contributed very little to the total benefit.
Professor Boccia concludes: 'These estimates are substantially more conservative than previous calculations that focused mainly on the first year of vaccination, but clearly demonstrate an important overall benefit from COVID-19 vaccination over the period 2020-2024. Most of the benefits, in terms of lives and life-years saved, have been secured for a portion of the global population who is typically more fragile, the elderly'.
