The report in the New England Journal of Medicine points out that recipients of mRNA COVID-19 vaccines have a 91% lower risk of contracting the infection compared with the unvaccinated. The study was funded by federal health agencies.
University of Utah–led researchers also emphasize that, even in the rare case that a breakthrough infection occurs, vaccination significantly reduces severity and duration of COVID-19 symptoms.
“One of the unique things about this study is that it measured the secondary benefits of the vaccine,” explained coauthor Sarang Yoon, DO, assistant professor at the University of Utah Rocky Mountain Center for Occupational and Environmental Health (RMCOEH). Dr. Yoon is also the principal investigator of the RECOVER (Research on the Epidemiology of SARS-CoV-2 in Essential Response Personnel) study in Utah.
The study, which was designed to measure infection risks for those on the front lines of the pandemic, analyzed preliminary data released by the CDC in March.
The authors said they embarked on the study because Information has been limited on the effectiveness of the two-dose messenger RNA (mRNA) vaccines BNT162b2 (Pfizer–BioNTech) and mRNA-1273 (Moderna) “in preventing infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and in attenuating coronavirus disease 2019 (Covid-19) when administered in real-world conditions.”
Their prospective cohort study involved 3,975 healthcare personnel, first responders, and other essential and frontline workers from December 14, 2020, to April 10, 2021. Participants had weekly SARS-CoV-2 PCR testing, with the virus detected in 204 participants (5%), of whom 5 were fully vaccinated (≥14 days after dose 2), 11 partially vaccinated (≥14 days after dose 1 and <14 days after dose 2), and 156 unvaccinated. Any COVID-19-like symptoms, including fever, shortness of breath, and loss of taste and smell, also were reported.
Results indicated that mRNA COVID-19 vaccines were:
• 91% effective in reducing risk for infection once participants were “fully” vaccinated, 2 weeks after the second dose.
• 81% effective in reducing risk for infection after “partial” vaccination, 2 weeks after the first dose but before the second dose was given.
The study also found that, among participants with SARS-CoV-2 infection, the mean viral RNA load was 40% lower (95% CI, 16 to 57) in partially or fully vaccinated participants than in unvaccinated participants. The study also determined that:
• Presence of fever was reduced 58% among those vaccinated with a breakthrough infection.
• Days spent sick in bed were reduced by 60% among those who developed a breakthrough infection.
• Detection of the virus was reduced by 70% among those with breakthrough infections, from 8.9 days to 2.7 days.
• The only three participants who were hospitalized were not immunized.
“Authorized mRNA vaccines were highly effective among working-age adults in preventing SARS-CoV-2 infection when administered in real-world conditions, and the vaccines attenuated the viral RNA load, risk of febrile symptoms, and duration of illness among those who had breakthrough infection despite vaccination,” the researchers concluded.
“We gave these vaccines to some of the highest risk groups in this country—doctors, nurses, and first responders,” Dr. Yoon explained. “These are the people who are getting exposure to the virus day in and day out, and the vaccine protected them against getting the disease. Those who unfortunately got COVID-19 despite being vaccinated were still better off than those who didn’t.”
The HEROES-RECOVER network recruited 3,975 participants at eight sites—Salt Lake City, Utah; Miami, Florida; Temple, Texas; Portland, Oregon; Duluth, Minnesota; and Phoenix and Tucson, Arizona.
The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.