Covid-19 infections among frontline healthcare workers could be going undetected and unrecognized, warns CDC
Frontline healthcare workers not only face a higher risk of exposure to Covid-19, but they can also pass on the infection to patients, coworkers, and others in the community
A high proportion of Covid-19 infections among frontline healthcare workers could be slipping under the radar, according to the Morbidity and Mortality Weekly Report of the US Centers for Disease Control and Prevention (CDC). Face masks and universal screening are crucial to limiting the spread, they added.
Frontline healthcare personnel (HCP) not only face a higher risk of exposure to Covid-19, but they can also pass on the infection to patients, coworkers, and others in the community. But data on the prevalence and the nature of the disease is scarce. "Consistent with persons in the general population with SARS-CoV-2 infection, many frontline HCP with SARS-CoV-2 infection might be asymptomatic or minimally symptomatic during infection, and infection might be unrecognized," the CDC wrote in their report.
The study involved 3,248 participants working on the frontlines at 13 medical centers across the US. Between April 3–June 19, 2020, researchers tested them for the presence of antibodies against the virus. Most Covid-19 patients develop antibodies to SARS-CoV-2 proteins within a week or two of the infection. The healthcare workers provided details on any potential Covid-19 symptoms, previous testing, and their use of personal protective equipment (PPE) in the past week.
Of the 3,248 participants, 194 or 6% had developed antibodies, suggesting a previous infection. And among the 194, 56 or 29% reported no symptoms since February 1, 2020. About 86 or 44% did not believe that they previously had Covid-19, and 133 or 69% did not report a previous diagnosis. "These findings suggest that some SARS-CoV-2 infections among frontline HCP are undetected and unrecognized, possibly because of the minimally symptomatic or subclinical nature of some infections, underreporting of symptoms, or nonsystematic testing of some personnel with symptomatic infections," the CDC said.
The study participants were nurses, physicians, nurse practitioners, or physician assistants, respiratory therapists, and others. And among them, 40% reported working primarily in an ICU while 35% in an ED, and 25% in other locations. The median age of participants was 36 years, and 80% of them had no underlying health conditions. What is more, the prevalence of antibodies was 5.6% in participants who used masks before tending to patients, compared to 9% in their counterparts who did not use face coverings. Since February 1, 2020, 398 or 12% participants reported shortages of PPE.
PPE shortages and no universal face coverings are likely to have contributed to Covid-19 among healthcare personnel. Therefore, the CDC has called for enhanced screening, including frequent testing of frontline HCP, and universal use of face coverings in hospitals, to reduce SARS-CoV-2 transmission. The study has a few limitations, including that they may have underestimated the prevalence of antibodies as some participants may have developed a weak immune response to the infection. Further, the team did not gather information on facility-level infection prevention and control practices and its possible effects on exposure risk. The report could not identify if participants contacted the infection either within the hospital setting or the community.