Large, real-world study finds covid-19 vaccination more effective than natural immunity in protecting against all causes of death, hospitalizations


Large, real-world study finds covid-19 vaccination more effective than natural immunity in protecting against all causes of death, hospitalizations

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Reviewed by Emily Henderson, B.Sc.Dec 16 2022

In one of the first large, real-world studies comparing the effectiveness of COVID-19 vaccines versus natural immunity in protecting against death, hospitalizations and emergency department (ED) visits for any cause, including COVID, research-scientists from Regenstrief Institute, Indiana University School of Medicine and Vanderbilt University Medical Center report that people of all age groups benefited significantly more from vaccination than natural immunity acquired from a previous COVID infection. The lower death rate of vaccinated individuals was especially impressive for adults ages 60 years or older.

Significantly, the all-cause death and hospital admission rates for vaccinated individuals were 37 percent lower than the rates for those with natural immunity acquired from previous COVID infection. The rate of ED visits for all causes was 24 percent lower for vaccinated individuals than for the previously infected.

“This large population study of the entire state of Indiana should encourage individuals everywhere to get themselves and their children vaccinated and not rely on natural immunity. While the incidence of COVID infection was higher in vaccine recipients (6.7 percent) than in individuals previously infected (2.9 percent), the vaccine protected against severe disease while natural immunity did not confer the same benefit,” said study corresponding author and Regenstrief Institute Vice President for Data and Analytics Shaun Grannis, M.D. “As vaccinated individuals were more likely to actually get COVID than those with natural immunity, the lower death rate of vaccine recipients who develop COVID appears to be due to vaccination and not to a tendency for risk-averse behaviors, such as mask-wearing, hand sanitizing and social distancing.”

The study concludes, “The significantly lower rates of all-cause ED visits, hospitalization and mortality in the vaccinated highlight the real-world benefits of vaccination. The data raises questions about the wisdom of reliance on natural immunity when safe and effective vaccines are available.”

“SARS-CoV-2 infection, hospitalization and death in vaccinated and infected individuals in Indiana USA, November 2020 – February 2022,” is published in the American Journal of Public Health. In addition to Drs. Grannis and Tu, authors are Pengyue Zhang, PhD, IU School of Medicine; Anna Roberts, M.S. and Katie S. Allen, B.S., Regenstrief Institute; Jennifer Williams, MPH, formerly with Regenstrief Institute; and Peter Embi, former Regenstrief Institute president and CEO, currently at Vanderbilt University Medical Center.


Regenstrief Institute


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