In this multistate analysis of hospitalizations for COVID-19–like illness among adults aged 18 years or older during January–September 2021 whose previous infection or vaccination occurred 90–179 days earlier, the adjusted odds of laboratory-confirmed COVID-19 were higher among unvaccinated and previously infected patients than among those who were fully vaccinated with 2 doses of an mRNA COVID-19 vaccine without previous documentation of a SARS-CoV-2 infection.
Study participants were over 5 times more likely to have COVID-19 if they were unvaccinated and had a prior infection
New research published today reinforces vaccination as the best protection against COVID-19. In a new MMWR study examining more than 7,000 people across 9 states who were hospitalized with COVID-like illness, researchers found that those who were unvaccinated and had a recent infection were 5 times more likely to have COVID-19 than those who were recently fully vaccinated and did not have a prior infection.
The data demonstrate that vaccination can provide a higher, more robust, and more consistent level of immunity to protect people from hospitalization for COVID-19 than infection alone for at least 6 months.
“We now have additional evidence that reaffirms the importance of COVID-19 vaccines, even if you have had prior infection. This study adds more to the body of knowledge demonstrating the protection of vaccines against severe disease from COVID-19. 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,” said CDC Director Dr. Rochelle P. Walensky.
The study looked at data from the VISION Network that showed among adults hospitalized with symptoms similar to COVID-19, unvaccinated people with prior infection within 3-6 months were 5.49 times more likely to have laboratory-confirmed COVID-19 than those who were fully vaccinated within 3-6 months with mRNA (Pfizer or Moderna) COVID-19 vaccines. The study was conducted across 187 hospitals.
Funded by CDC, the VISION network includes Columbia University Irving Medical Center (New York), HealthPartners (Minnesota and Wisconsin), Intermountain Healthcare (Utah), Kaiser Permanente Northern California (California), Kaiser Permanente Northwest (Oregon and Washington), Regenstrief Institute (Indiana), and University of Colorado (Colorado).
CDC continues to recommend everyone 12 and older get vaccinated against COVID-19.
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. Mobility and Mortality Weekly Report (MMWR), 29 October 2021 Early Release.
- Reduced Risk of Reinfection with SARS-CoV-2 After COVID-19 Vaccination — Kentucky, May–June 2021 CDC MMWR
- COVID-19 natural immunity versus vaccination Nebraska Med
- Why COVID-19 Vaccines Offer Better Protection Than Infection Johns Hopkins Bloomberg School of Public of Public Health