Illness is significantly milder in rare ‘breakthrough’ cases of the disease
People who receive mRNA COVID-19 vaccines are up to 91 percent less likely to develop the disease than those who are unvaccinated, according to a new nationwide study of eight sites, 包括盐湖城. For those few vaccinated people who do still get an infection, 或者“突破性”案例, the study suggests that vaccines reduce the severity of COVID-19 symptoms and shorten its duration.
研究ers say these results are among the first to show that mRNA vaccination benefits even those individuals who experience breakthrough infections.
“One of the unique things about this study is that it measured the secondary benefits of the vaccine,” Sarang Yoon， D.O., 研究的合著者, assistant professor at the University of Utah Rocky Mountain Center for Occupational and Environmental Health (RMCOEH), and principal investigator of the 恢复 (研究 on the Epidemiology of SARS-CoV-2 in Essential Response Personnel) study in Utah.
这项研究中, published online in the 新英格兰医学杂志, builds on preliminary data released by the Centers for Disease Control and Prevention (CDC) 3月.
的 study was designed to measure the risks and rates of infection among those on the front lines of the pandemic.
“We gave these vaccines to some of the highest risk groups in this country—doctors, 护士, 急救人员,Yoon说. “的se 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.”
的 study found that mRNA COVID-19 vaccines were:
- 91% effective in reducing risk for infection once participants were “fully” vaccinated, 第二次注射后两周.
- 81% effective in reducing risk for infection after “partial” vaccination, two weeks after the first dose but before the second dose was given.
的 HEROES-恢复 network recruited 3,975 participants at eight sites. 除了盐湖城, 地点包括迈阿密, Florida; Temple, Texas; Portland, Oregon; Duluth, Minnesota; and Phoenix and Tucson, as well as other areas in Arizona. Participants submitted samples for COVID-19 testing on a weekly basis for 17 weeks between Dec. 2020年4月13日和2021年4月10日. Participants also reported weekly whether they had COVID-19-like symptoms, 包括发烧, 呼吸急促（气促）, 失去味觉和嗅觉.
Only 204 (5%) of the participants eventually tested positive for SARS-CoV-2, 导致COVID-19的病毒. 这些, 156人未接种疫苗, 32 had an indeterminate vaccine status, and 16 were fully or partially vaccinated. 的 fully or partially vaccinated participants who developed breakthrough had milder symptoms than those who were unvaccinated:
- Presence of fever was reduced 58% percent 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% percent among those with breakthrough infections, from 8.9天至2天.7天.
- 的 three people who were hospitalized were not immunized, meaning that no one who developed a breakthrough infection was hospitalized.
的se findings also suggest that fully or partially vaccinated individuals who get COVID-19 might be less likely to spread the virus to others. 的 researchers found that infected study participants who had been fully or partially vaccinated when infected had 40% less detectable virus in the nose and did so for six fewer days compared to those who were unvaccinated.
整体, the researchers conclude the study’s findings support the CDC’s recommendation to get fully vaccinated as soon as possible.
“I hope these findings reassure the public that mRNA COVID-19 vaccines are safe and protect us from this severe disease,Yoon说.
的 恢复 研究正在进行中, and results from future phases will help determine how long COVID-19 vaccines protect against infection and the real-world effectiveness of newer vaccines. A new study will test the same questions in children 12 and older who are now eligible to receive the COVID-19 vaccination. 的 research will also investigate how well COVID-19 vaccines protect against new variants now circulating in the U.S., including the highly transmissible Delta variant of SARS-CoV-2.
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这项研究中, “Prevention and Attenuation of Covid-19 with the BNT162b2 and mRNA-1273 Vaccines,” 出现在 新英格兰医学杂志.
除了博士. 尹, 库尔特·海格曼，m.s.D., 中心主任； 马修·塞塞博士.D., 副教授、 安德鲁·菲利普斯，m.m.D., assistant professor of RMCOEH, were co-investigators on the Utah portion of the study.