For Immediate Release March 12, 2021


Michael Schwartzberg:

UM School of Medicine Researchers Find Biggest Risk Factor Is Having Known Exposure to Someone Who Tested Positive in Household or Community

Healthcare personnel who were infected with COVID-19 had stronger risk factors outside the workplace than in their hospital or healthcare setting. That is the finding of a new study published today in JAMA Network Open conducted by University of Maryland School of Medicine (UMSOM) researchers, colleagues at the Centers for Disease Control and Prevention (CDC) and three other universities.

The study examined survey data from nearly 25,000 healthcare providers in Baltimore, Atlanta, and Chicago including at University of Maryland Medical System (UMMS) hospitals. They found that having a known exposure to someone who tested positive for COVID-19 in the community was the strongest risk factor for testing positive for COVID-19. Living in a zip code with a high COVID-19 cumulative incidence was also a strong risk factor.

"The news is reassuring in that it shows the measures taken are working to prevent infections from spreading in healthcare facilities," said study co-author Anthony Harris, MD, MPH, Professor of Epidemiology & Public Health at UMSOM. "Vaccination for healthcare workers, however, should remain a priority because of continual exposures in the workplace. There is also an urgent need to keep healthcare providers healthy so they can care for sick patients and reduce the risk of transmitting the virus to vulnerable patients."

Researchers from Emory University School of Medicine and Rollins School of Public Health in Atlanta, Rush University Medical Center in Chicago, and Johns Hopkins University School of Medicine also participated in this study. UMSOM faculty Robert Christenson, PhD, Brent King, MD, Surbhi Leekha, MBBS, Lyndsay O'Hara, PhD, Peter Rock, MD, MBA, and Gregory Schrank, MD, were co-authors on this study. The study was funded by CDC's Prevention Epicenters Program.

"Factors presumed to contribute most to infection risk among healthcare providers, including caring for COVID-19 patients, were not associated with increased risk in this study," said study co-author Sujan Reddy MD, an infectious disease specialist at the CDC. "The highest risks to healthcare workers may be from exposures in the community."

The study did, however, have some important caveats. Since infection control practices were not standardized across the various healthcare sites, the study could not determine the level of effectiveness of personal protective equipment (N95 respirator, surgical mask, gowns, face shields). Nor could the study determine whether certain infection control practices, such as frequent disinfection of surfaces in exam rooms, were better than others in preventing infection spread.

Confirming evidence from other studies, this study found that Black Americans who were healthcare personnel were more likely to test positive for COVID-19 infections than their white counterparts. This may be due to existing disparities in community exposure rather than from healthcare-associated exposures.

"We're proud of this very important collaborative clinical work with our research colleagues," said Mohan Suntha, MD, MBA, President and CEO of UMMS. "We have made the safety of our team members a top priority throughout this pandemic, and it is incredibly gratifying to see that our efforts to prevent the spread of COVID-19 in hospitals have worked. This is also another example of the importance of the partnership between our academic-focused health care System and the groundbreaking discovery-based medicine work happening every day at the UM School of Medicine."

"As front-line and support staff at hospitals and health systems continue to tirelessly battle COVID-19, they can draw reassurance in this important research finding that the infection control measures in place protected themselves and their families," said E. Albert Reece, MD, PhD, MBA, Executive Vice President for Medical Affairs, UM Baltimore, and the John Z. and Akiko K. Bowers Distinguished Professor and Dean, University of Maryland School of Medicine. "We need to know that we are doing all we can to protect our healthcare heroes, from providing them with adequate protective gear to giving them early access to vaccines."


About the University of Maryland School of Medicine

Now in its third century, the University of Maryland School of Medicine was chartered in 1807 as the first public medical school in the United States. It continues today as one of the fastest growing, top-tier biomedical research enterprises in the world -- with 45 academic departments, centers, institutes, and programs; and a faculty of more than 3,000 physicians, scientists, and allied health professionals, including members of the National Academy of Medicine and the National Academy of Sciences, and a distinguished two-time winner of the Albert E. Lasker Award in Medical Research. With an operating budget of more than $1.2 billion, the School of Medicine works closely in partnership with the University of Maryland Medical Center and Medical System to provide research-intensive, academic and clinically based care for nearly 2 million patients each year. The School of Medicine has more than $563 million in extramural funding, with most of its academic departments highly ranked among all medical schools in the nation in research funding. As one of the seven professional schools that make up the University of Maryland, Baltimore campus, the School of Medicine has a total population of nearly 9,000 faculty and staff, including 2,500 student trainees, residents, and fellows. The combined School of Medicine and Medical System ("University of Maryland Medicine") has an annual budget of nearly $6 billion and an economic impact more than $15 billion on the state and local community. The School of Medicine, which ranks as the 8th highest among public medical schools in research productivity, is an innovator in translational medicine, with 600 active patents and 24 start-up companies. The School of Medicine works locally, nationally, and globally, with research and treatment facilities in 36 countries around the world. Visit

About the University of Maryland Medical System

The University of Maryland Medical System (UMMS) is a university-based regional health care system focused on serving the health care needs of Maryland, bringing innovation, discovery and research to the care we provide and educating the state's future physician and health care professionals through our partnership with the University of Maryland School of Medicine and the UM Schools of Nursing, Pharmacy, Social Work and Dentistry in Baltimore. As one of the largest private employers in the State, the health system's 28,000 employees and 4,000 affiliated physicians provide primary and specialty care in more than 150 locations and at 13 hospitals. UMMS' flagship academic campus, the University of Maryland Medical Center in Baltimore is partnered with the University of Maryland School of Medicine and is recognized regionally and nationally for excellence and innovation in specialized care. Our acute care and specialty rehabilitation hospitals serve urban, suburban and rural communities and are located in 13 counties across the State. For more information, visit