How Health Care Workers in Minnesota Were Exposed to COVID-19, March–July 2020

Health care personnel (HCP) face a higher risk of COVID-19 from exposure to patients and community contacts. After Minnesota's first confirmed case on March 6, 2020, the Minnesota Department of Health (MDH) required health care facilities to report staff exposures to people with confirmed COVID-19, so each could be risk-assessed and workers with higher-risk exposures could be quarantined and monitored.

How the program worked

Facilities first assessed each exposure. A higher-risk exposure meant close, prolonged contact with a confirmed case — or with their secretions or excretions — without recommended protective equipment, or close, prolonged contact with a case at home or in the community; the report's summary describes it as within 6 feet, for 15 minutes or more, or during an aerosol-generating procedure. MDH staff did 20-minute phone interviews with workers whose risk was higher or unclear, asking how the exposure happened, what protective equipment they wore and whether it failed.

Workers with higher-risk exposures were advised to quarantine voluntarily — staying away from work and the community — with daily MDH health monitoring by emailed survey for 14 days after their last exposure, and to get tested if symptoms developed. Where facilities faced critical staff shortages, workers without symptoms could return to work during quarantine if they wore appropriate protective equipment.

What they found

From March 6 to July 11, 2020, MDH and 1,217 facilities assessed 17,330 workers for 21,406 exposures. The exposures came from acute or ambulatory care patients (21%), residents of congregate living or long-term care (24%), coworkers (25%), outbreaks in congregate settings (25%) and household or social contacts (5%).

5,374 (25%) were higher-risk. Of these, 597 (11%) involved workers who cared for patients at more than one facility. Where known, the workers' mean age was 39 (range 16–80), and the most common roles were nursing assistants or patient care aides (40%), nurses (30%), administration (5%), medical providers (5%) and environmental services (3%).

Two-thirds (66%) of higher-risk exposures came from direct patient care and 34% from contact outside it — coworkers, family and friends. One COVID-19 case in long-term care exposed a median of three workers, against one in acute or ambulatory care; an infected worker exposed a median of two coworkers.

Protective equipment

Symptoms and monitoring

By July 11, 3,580 (67%) of workers with higher-risk exposures had enrolled in monitoring. Of 3,399 who completed it, 1,060 (31%) reported COVID-19–like symptoms, a median of 7 days after exposure. Group-home workers had the highest positivity during monitoring (16%).

Compared with acute care workers, those in congregate living or long-term care more often worked after a higher-risk exposure (57% versus 37%), worked while symptomatic (4.8% versus 1.3%) and tested positive during monitoring (9.6% versus 3%).

What it means

• Long-term care needs targeted protection. Its workers wore protective equipment less, worked sick more and were infected more — and can bring the virus into facilities where residents and coworkers are at high risk. Such facilities often face equipment and staffing shortages, and staff often lack formal infection-control training.
• Exposure outside patient care matters. About a third of higher-risk exposures came from coworkers and home or social contacts, and household and social exposures had the highest positivity. Breakrooms, nursing stations and other gathering spots are places where staff may drop distancing and masks. Minnesota sequencing found genetically diverse virus in some nursing-home workers, pointing to community and household infection.
• What helps: better infection prevention and control, consistent protective equipment, flexible sick leave and access to testing. Proper equipment use could also mean fewer workers quarantined and less strain on staffing.

Limits

Facilities did the first risk assessments, so some exposures may have been misclassified; not every facility reported, and MDH could not reach or enroll every worker; and some infections during monitoring may have come from unrecognized community exposure.

Sources

Based on Fell A, Beaudoin A, D'Heilly P, et al., "SARS-CoV-2 Exposure and Infection Among Health Care Personnel — Minnesota, March 6–July 11, 2020," MMWR Vol. 69, No. 43, CDC; a work of the United States government in the public domain. The report's introduction says 52% of symptomatic workers in monitoring tested positive, while its table shows 51.6% of them were tested; neither figure is given here. Its social-media graphic is not reproduced.