Nov. 1, 2021 -- Unvaccinated people who had a recent infection were five times more likely to be reinfected with the coronavirus compared to those who were fully vaccinated and didn’t have a prior infection, according to a new study published Friday in the CDC’s Morbidity and Mortality Weekly Report.

The research team concluded that vaccination can provide a higher, stronger, and more consistent level of immunity against COVID-19 hospitalization than infection alone for at least six months.

“We now have additional evidence that reaffirms the importance of COVID-19 vaccines, even if you have had prior infection,” Rochelle Walensky, MD, director of the CDC, said in a statement.

“This study adds more to the body of knowledge demonstrating the protection of vaccines against severe disease from COVID-19,” she said. “The best way to stop COVID-19, including the emergence of variants, is with widespread COVID-19 vaccination and with disease prevention actions such as mask wearing, washing hands often, physical distancing and staying home when sick.”

Researchers looked at data from the VISION Network, which included more than 201,000 hospitalizations for COVID-like illness at 187 hospitals across nine states between Jan. 1 to Sept. 2. Among those, more than 94,000 had rapid testing for the coronavirus, and 7,300 had a lab-confirmed test for COVID-19.

The research team found that unvaccinated people with a prior infection within 3 to 6 months were about 5-1/2 times more likely to have laboratory-confirmed COVID-19 than those who were fully vaccinated within 3 to 6 months with the Pfizer or Moderna shots. They found similar results when looking at the months that the Delta variant was the dominant strain of the coronavirus.

Importantly, the research team noted, these estimates may change over time as immunity wanes. Future studies should consider infection-induced and vaccine-induced immunity as time passes during the pandemic, they wrote.

Additional research is also needed for the Johnson & Johnson vaccine, they wrote. Those who have received the Johnson & Johnson vaccine are currently recommended to receive a booster shot at least two months after the first shot.

Overall, “all eligible persons should be vaccinated against COVID-19 as soon as possible, including unvaccinated persons previously infected,” the research team concluded.

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CDC: “Morbidity and Mortality Weekly Report: Laboratory-Confirmed COVID-19 Among Adults Hospitalized with COVID-19-Like Illness with Infection-Induced or mRNA Vaccine-Induced SARS-CoV-2 Immunity — Nine States, January-September 2021.” “New CDC Study: Vaccination Offers Higher Protection than Previous COVID-19 Infection.”

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