Nurses and other bedside caregivers are far less likely to catch COVID-19 after risky exposures to patients than in interactions at home or in the community, new data show. And caregivers are twice as likely to be diagnosed with COVID after exposures to a co-worker in a break room than after patient exposures.
Those are some key takeaways from an analysis of more than 5,000 higher-risk health care worker exposures between March and July in Minnesota, which was published Thursday.
The study also found that higher-risk exposures in congregate care settings, like nursing homes and group homes, remain riskier than hospitals, though the incidence and risk have each fallen since July.
Public health officials said Thursday that trends in the data show the effectiveness of ubiquitous use of personal protective equipment (PPE) in hospitals and many nursing homes, including medical-grade face masks and eye protection.
"If they have proper PPE, and they use it correctly, they can dramatically reduce their risk to a level probably not much different from an average member of the community," said Ryan Demmer, associate professor of epidemiology and community health at the University of Minnesota.
Such protections are not typically observed at home or in the community, which is a key reason for the higher risk of getting the virus from a community exposure.
Interactions with contagious family members also tends to be more intimate and longer in duration, which increases risks.
State infectious disease director Kris Ehresmann said all residents need to recognize that high level of community transmission has a direct effect on health care facilities, underscoring the importance of basic steps like masking and distancing in public.
"I think the message for health care personnel is that, while you know you have a high risk of potential for exposure in the workplace ... you need to recognize that your risk is actually higher in the community at this point," Ehresmann said.
The data were derived from contact tracing by the Minnesota Department of Health after it was notified of an exposure by the health care providers' employers. The analysis found variability in risk across different kinds of providers.
In general, exposures in congregate care settings were more risky for health care workers than in hospitals.
Contact tracing found that those who work in nursing homes and other congregate settings were less likely to have worn masks or eye protection and more likely to develop COVID after higher-risk exposures.
Amanda Beaudoin, an epidemiologist with the state Health Department, said some congregate care facilities had significant shortages of PPE and chronic understaffing during the early months of the pandemic in Minnesota.
But PPE availability has improved since July, and the number of higher-risk exposures in congregate settings has fallen. In April, the Health Department identified 780 higher-risk exposures to outbreaks or positive residents. In September, that number had fallen to 69.
"This is because we are preventing these higher-risk exposures in long-term care through having improved availability of PPE, [diagnostic] testing, and training. And there is a higher awareness of transmission. So that is good news," Beaudoin said.
The Minnesota Nurses Association, whose members work in hospitals, said Thursday that some workers are still being exposed in health care facilities because of inadequate protective equipment.
The nurses union also said exposures are driven by human resource policies at hospitals, including some that force workers to return to work before their quarantine period ends, and others that penalize nurses by withholding regular pay while they're out of work for testing or quarantine.
The March-to-July data show that for higher-risk exposures to COVID-positive patients in the hospital, 1.3% are followed by positive diagnosis for COVID in the health care worker within 14 days, according to contact tracing.
In contrast, 3.8% of higher-risk exposures to COVID-positive co-workers on the job led to a positive case in the exposed worker.
And 12.5% of documented higher-risk exposures in the community or at home led to a positive diagnosis in the health care workers. Cases in which health care workers infect each other outside of work, like at a wedding, are included in the community-transmission statistic.
"That says to me that the personal protective equipment that has been chosen is working," Sylvia Garcia-Houchins, director of infection prevention and control at Illinois-based hospital accreditation group Joint Commission, said Thursday.
PPE also helps explain the higher rate of worker-to-worker transmission, vs. infections spread by patients.
Dr. Laura Breeher, medical director of occupational health at Mayo Clinic, said in a press call earlier this week that transmission among health care workers typically happens because of a lapse in protective equipment, often in a break room or dining area.
"It might be a situation where two individuals have lunch together, and think they are socially distant more than 6 feet, when they are not," she said. "So whereas they may have thought they had no risk of exposure, they actually had a high-risk exposure." In nursing homes and long-term care facilities, 7.3% of confirmed exposures to positive patients tracked by MDH were followed by the worker developing COVID.
Contact with outbreaks at those centers were even more risky. Defined as situations where the worker is exposed to at least four cases in the same facility at the same time, the worker got COVID after 10.9% of these incidents.
Labor officials said the study demonstrates the need for wider distribution of PPE at hospitals, among other things.
"We call on the [Minnesota Department of Health and Minnesota Hospital Association] to increase the supplies of PPE to all health care workers.
"No single percentage point, no single infection is acceptable when we can protect all health care workers," the Minnesota Nurses Association said in a statement.