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For people who have recovered from a COVID-19 infection, vaccination reduces the risk for reinfection by half, compared with natural immunity alone, according to a new report.
Examining data from more than 18 million people across the world, Italian researchers also found that vaccination halves the risk of developing severe COVID-19 symptoms during a reinfection.
“Our results confirm that, among the recovered, those who have received two or three doses of vaccine have a 50% to 60% lower risk of reinfection than those who are not vaccinated,” study author Lamberto Manzoli, MD, a medical epidemiologist and director of the University of Bologna’s School of Public Health and Hygiene, Bologna, Italy, told Medscape Medical News.
“Considering that the number of people who recovered is now in the hundreds of millions worldwide, these results appear particularly encouraging and provide strategic information for future pandemic control policies,” he said.
The study was published November 9 in Frontiers in Medicine.
Calculating Risk
Manzoli and colleagues analyzed data from 18 studies conducted worldwide through July 2022. The studies included more than 18 million participants and evaluated the risk for COVID-19 reinfection among vaccinated and unvaccinated patients. The research team defined severe disease as requiring hospital admission without need of an intensive care unit and critical disease as requiring hospital admission in an i …