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June 9, 2021/News Releases

Cleveland Clinic Statement on Previous COVID-19 Infection Research

Updated August 16, 2021

Medical Series–injection

Cleveland Clinic recommends those who are eligible receive the COVID-19 vaccine.

In June, we shared research that provided insight into how the immune system protects the body after a confirmed COVID-19 infection. The study followed Cleveland Clinic caregivers over five months as the vaccination process was beginning. The data showed that the vaccine was extremely effective in preventing COVID-19 infection. In addition, during the study, none of the employees who had confirmed positive PCR tests and remained unvaccinated were re-infected. It’s important to note that this study was conducted in late 2020 and early 2021, before the emergence of the Delta variant.

More research is needed. We do not know how long the immune system will protect itself against re-infection after COVID-19, as our study only looked at individuals over a five-month period, or how well-protected previously infected individuals are against variants. It is also important to keep in mind that this study was conducted in a population that was younger and healthier than the general population.

It is safe to receive the COVID-19 vaccine even if you have previously tested positive, and we recommend all those who are eligible receive it.

About Cleveland Clinic

Cleveland Clinic is a nonprofit multispecialty academic medical center that integrates clinical and hospital care with research and education. Located in Cleveland, Ohio, it was founded in 1921 by four renowned physicians with a vision of providing outstanding patient care based upon the principles of cooperation, compassion and innovation. Cleveland Clinic has pioneered many medical breakthroughs, including coronary artery bypass surgery and the first face transplant in the United States. Cleveland Clinic is consistently recognized in the U.S. and throughout the world for its expertise and care. Among Cleveland Clinic’s 82,600 employees worldwide are more than 5,786 salaried physicians and researchers, and 20,700 registered nurses and advanced practice providers, representing 140 medical specialties and subspecialties. Cleveland Clinic is a 6,728-bed health system that includes a 173-acre main campus near downtown Cleveland, 23 hospitals, 280 outpatient facilities, including locations in northeast Ohio; Florida; Las Vegas, Nevada; Toronto, Canada; Abu Dhabi, UAE; and London, England. In 2024, there were 15.7 million outpatient encounters, 333,000 hospital admissions and observations, and 320,000 surgeries and procedures throughout Cleveland Clinic’s health system. Patients came for treatment from every state and 112 countries. Visit us at clevelandclinic.org. Follow us at x.com/CleClinicNews. News and resources are available at newsroom.clevelandclinic.org.

Editor’s Note: Cleveland Clinic News Service is available to provide broadcast-quality interviews and B-roll upon request. 

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