CLEVELAND – A study by Cleveland Clinic staff found that those previously infected with COVID-19 were unlikely to be re-infected even if they were not vaccinated.
Research like this can help countries that have not yet received a large supply of vaccines to prioritize who gets shot first. In the United States, vaccines are easy to access and free of charge.
Like all research, the study was limited in scope, but its authors nonetheless made broad claims.
Subjects previously infected with SARS-CoV-2 are unlikely to receive COVID-1
“Our study examined rates of SARS-CoV-2 infection in vaccinated and non-vaccinated individuals and showed that those previously infected who did not receive the vaccine did not have higher SARS-CoV-2 infection than those previously infected who received that which provided direct evidence that vaccination does not add protection to those previously infected. “
The survey was conducted on 52,238 employees at the Cleveland Clinic. A positive RT-PCR test was defined as a COVID-19 infection. Among those in the study, 2,579 were previously infected, and 54% of this group remained unvaccinated. None of these 2,759 employees were reinfected.
When asked to comment on the study, the Cleveland Clinic issued this statement.
The Cleveland Clinic recommends that those eligible receive the COVID-19 vaccine.
We recently shared research that provides insight into how the immune system protects the body after a confirmed COVID-19 infection. The study followed Cleveland Clinic nurses for five months as the vaccination process began. The data showed that the vaccine was extremely effective in preventing COVID-19 infection. In addition, we found that none of the previously infected employees who remained unvaccinated were re-infected during the course of the study. This information can help guide vaccination efforts if there is a lack of vaccine supply and in countries where vaccine supply is limited.
This is still a new virus and more research is needed. It is important to keep in mind that this study was conducted in a population that was younger and healthier than the general population. In addition, we do not know how long the immune system will protect itself against reinfection after COVID-19. It is safe to receive the COVID-19 vaccine even if you have tested positive in the past and we recommend that all those who are eligible receive it.
Limitations of the study
The authors acknowledged an obvious limitation in their work. Because there was no policy of asymptomatic screening of employees, “previously infected individuals who remained asymptomatic could possibly have been pre-classified as previously uninfected. Given this limitation, one should be careful to draw conclusions about the protective effect of previous asymptomatic SARS-CoV-2 infection. “
In addition, 12% of caregivers classified as previously infected had no symptom date recorded, suggesting that at least some who were classified as previously infected may have had asymptomatic infections.
The authors said the duration of the five-month study was short, but that it was longer than the published mRNA vaccine efficacy studies to date.
The study also did not include children and a few elderly subjects, and the majority of those examined would not have been immunosuppressed.
It is also not known how this study would keep up with newer variants.
Strengths of the study
The study also cited some of its strengths, including the large sample size and length. The follow-up of up to five months gave the researchers a “sufficient degree of confidence in the results.”
Researchers selected staff cohorts at the clinic because of documentation for their COVID-19 vaccination. A hospital is a place where any COVID-19 infection would be detected.
“Given that this was a survey among employees of a healthcare system, and that the healthcare system had policies and procedures to recognize the critical importance of keeping track of the pandemic among its employees, we had an accurate record of who had COVID- 19, when they were diagnosed with COVID-19, who received a COVID-19 vaccine, and when they received it, “the authors wrote.
The results have important implications globally, the authors said. In countries where vaccine supply is limited, it would be best to give the vaccine first to those who are not infected.
The study said that as of May 17, only 17 countries had been able to reach 10% or more of their population with at least the first dose.
Click here to access the full survey.
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