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COVID Vaccines Five Times More Effective Than Previous Infection In Preventing Hospitalizations


Rachael Funnell

Social Editor and Staff Writer

clockNov 1 2021, 16:21 UTC
covid vaccination hospitalization

Recovering from COVID-19 once doesn't guarantee it won't hospitalize you in the future. Image credit: Terelyuk /

If you have already had COVID, you might be thinking that further immunizations aren’t necessary since your body has already fought the illness. However, a recent study from the Centers for Disease Control and Prevention (CDC) has shown why committing to getting fully vaccinated is crucial even if you’ve already had the disease.

The nationwide study looked at rates of hospitalizations for COVID-19 among patients who were fully vaccinated and those who were unvaccinated with a history of infection with the SARS-CoV-2 virus. Their results showed that people relying on immunity from a previous infection had a five-fold greater likelihood of being hospitalized with COVID-related symptoms from future infection compared to those who kept up to date with their vaccines.


To investigate if a correlation existed, the CDC’s VISION Network collated data from 201,000 hospitalizations in states within the US. They then whittled this sample down to a group of 7,000 people who qualified to be included in the study.

It then compared data from unvaccinated individuals who had tested positive for the disease more than three months before being hospitalized, as well as people who’d received the Moderna or Pfizer vaccines who hadn’t tested positive for the disease. The comparison revealed that unvaccinated patients who had been sick were 5.49 times more likely to be hospitalized with their next infection compared to vaccinated patients being infected for the first time.

“This data provides powerful evidence that vaccinations offer superior protection against COVID-19 than relying on natural immunity alone,” said Shaun Grannis, vice president for data and analytics at Regenstrief Institute and professor of family medicine at Indiana University School of Medicine, in a statement. “Many have been asking if they should get vaccinated if they’ve already been infected – this research shows the answer is yes.”


As a general rule, when our bodies fight infection the immune system learns to recognize the pathogen should it invade the body again which is why some people either don’t get sick, or get much less sick the second time they contract an illness. However, the efficiency of your immune system can vary for a multitude of reasons and so previous infection isn’t a fail-safe approach for preventing severe illness.

“The study findings are consistent with laboratory evidence that mRNA vaccines create high levels of antibodies,” concluded the study authors. “[W]hereas those who recover from COVID-19 have varying levels of antibodies, especially if they experienced mild symptoms or were asymptomatic.”

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