Hours of direct contact and percent facemask use were summarized as monthly averages, and then each week was categorized as above or below the corresponding monthly average. 6, 7 As rotating questions in weekly surveys, participants reported hours in the past 7 days of direct contact (within 3 ft.) and associated percentage facemask use with people at work, in the community, or in any setting who may have COVID-19. Active surveillance is conducted with weekly participant or medical record reports for COVID-19-like illness (CLI) defined as ≥1 symptom of fever, chills, cough, shortness of breath, sore throat, diarrhea, muscle aches, or change in smell or taste. The HEROES-RECOVER Network includes Arizona Healthcare, Emergency Response, and Other Essential Workers Surveillance Study (HEROES) conducted in Phoenix, Tucson, and other noncentrally located areas in Arizona and Research on the Epidemiology of SARS-CoV-2 in Essential Response Personnel (RECOVER) conducted in Miami, Florida, Duluth, Minnesota, Portland, Oregon, Temple, Texas, and Salt Lake City, Utah. Here, we demonstrate that COVID-19 vaccines dramatically reduced the risk of any SARS-CoV-2 infection among vaccinated adults at high occupational risk of exposure, and substantial protection continues to be evident despite the high prevalence of the Delta variant during recent months. Using data from the CDC HEROES-RECOVER Network, a prospective frontline worker cohort, we examined changes in the monthly incidence of COVID-19 by vaccination status, as well as the association of additional factors of occupation, demographics, physical distancing, and mask use with risk of infection. Particularly at increased risk of SARS-CoV-2 infection are frontline workers, including healthcare personnel, first responders, and essential and other frontline workers who provide direct care and services to the public. 1- 5 Changes in COVID-19 VE estimates associated with changes in predominating variant virus circulation over time may have important implications for infection risk in work and community settings. Our data demonstrate the added protective benefit of facemask use among both unvaccinated and vaccinated frontline workers.ĬOVID-19 vaccines have shown >90% effectiveness in preventing SARS-CoV-2 infection, but estimates of vaccine effectiveness (VE) declined to 66% during B.1.617.2 (Delta) predominance. ConclusionsĬOVID-19 vaccination was significantly associated with a lower risk of SARS-CoV-2 infection despite Delta variant predominance. Below average facemask use was associated with a higher risk of infection for unvaccinated participants during exposure to persons who may have COVID-19 and vaccinated participants during hours in the community. In contrast, there was no reportable incidence among fully vaccinated participants at the end of January 2021, and incidence remained low until September 2021 when it rose modestly to 4.1 (95% CI 1.9–3.8) per 1000. By September 2021, when the Delta variant predominated, incidence had once again risen to 13.6 (95% CI 7.8–19.4) per 1000 person-weeks. ResultsĪmong 1018 unvaccinated and 3531 fully vaccinated workers, the monthly incidence of laboratory-confirmed SARS-CoV-2 infection in January 2021 was 13.9 (95% confidence interval : 10.4–17.4), declining to 0.5 (95% CI -0.4-1.4) per 1000 person-weeks in June. ![]() ![]() Participants completed baseline and quarterly surveys, and each week self-collected mid-turbinate nasal swabs and reported symptoms. We analyzed data from a prospective frontline worker cohort to estimate the incidence of COVID-19 by month as well as the association of COVID-19 vaccination, occupation, demographics, physical distancing, and mask use with infection risk. ![]() We sought to evaluate the impact of changes in estimates of COVID-19 vaccine effectiveness on the incidence of laboratory-confirmed infection among frontline workers at high risk for SARS-CoV-2.
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