People who received both doses of Pfizer-BioNTech's messenger RNA vaccine and had no symptoms had an 80 percent lower risk of testing positive for COVID-19 compared to those who were unvaccinated, according to research published March 10 in Clinical Infectious Diseases.
Researchers from Rochester, Minn.-based Mayo Clinic reviewed molecular screening tests for SARS-CoV-2 performed in adult patients across several of the health system's locations between Dec. 17, 2020, and Feb. 8, 2021. Overall, 48,333 pre-procedural screenings tests were conducted for 39,156 patients during the study period.
Out of 3,006 pre-procedural screening tests performed on patients without COVID-19 symptoms and who had previously received at least one dose of mRNA vaccine, 42 tested positive for the virus. Among 45,327 screenings performed on unvaccinated patients without symptoms, 1,436 tested positive for COVID-19.
"We found that those patients without symptoms receiving at least one dose of the first authorized mRNA COVID-19 vaccine, Pfizer-BioNTech, 10 days or more prior to screening were 72 percent less likely to test positive," said Aaron Tande, MD, infectious diseases specialist at Mayo Clinic and study co-author. "Those receiving two doses were 73 percent less likely, compared to the unvaccinated group."
For patients who had received both doses, researchers observed an 80 percent reduced risk of testing positive for COVID-19 after adjusting for other factors.
To view the full study, click here.
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