Discussion

The proportion of HCP with COVID-19 was highest in the ED and lowest among those working remotely. COVID-19 and non–COVID-19 units had similar proportions of HCP with COVID-19. Cases decreased across all work locations following COVID-19 vaccination.

In our hospital, the proportion of HCP with COVID-19 was highest in the ED. Although this association has not been well established, these results are similar to data published in New York City and Iran. ^{Reference Sabetian, Moghadami and Hashemizadeh Fard Haghighi2,Reference Purswani, Bucciarelli and Tiburcio4} HCP in the ED may have been exposed to patients during the peak of their infectious period. Emergent aerosol-generating procedures, such as cardiopulmonary resuscitation, without proper PPE might have contributed to higher rates. During the study period, our policy was to isolate any patient who presented to the ED with respiratory symptoms to a designated area upon screening. However, a previous study demonstrated that SARS-CoV-2 transmission from asymptomatic individuals accounted for ∼60% of all transmissions. ^{Reference Johansson, Quandelacy and Kada5} Stricter infection control measures, such as increased air exchanges and universal N95 use, should be considered for HCP in the ED during periods of high community transmission. ^{Reference Dau, Peled, Lau, Lyou and Skinner6,Reference Allen and Ibrahim7}

Whether working on COVID-19 units is associated with an increased risk of acquiring COVID-19 remains a controversial topic; data have been inconsistent. ^{Reference Akinbami, Chan and Vuong8–Reference Nygren, Noren, De Marinis, Holmberg, Fraenkel and Rasmussen10} COVID-19 units and non–COVID-19 units had similar proportions of HCP with COVID-19 at UIHC. This finding might suggest that infection control practices reduced the risk of SARS-CoV-2 acquisition from patients with known or suspected COVID-19. All rooms in the COVID-19 units had high air exchange rates and negative pressure. Patients admitted for COVID-19–related reasons may have had a lower viral load by the time they were admitted. Transmission risk may be higher from patients on non–COVID-19 units who were not suspected to have COVID-19. Ensuring the availability of appropriate PPE, keeping safety measures and guidelines updated, and monitoring compliance of infection control measures are essential to reduce the risk of acquiring COVID-19 for frontline HCP in non–COVID-19 units.

The proportion of HCP with COVID-19 was second lowest among those working in perioperative locations such as preoperative or recovery areas. All patients underwent preprocedure testing during the study period, which may have contributed to a smaller proportion of HCP acquiring COVID-19. The job title of medical assistant was associated with the highest case proportion. These HCP perform a variety of tasks involving close patient contact, which may put them at increased risk.

This study had several limitations. HCP without dedicated work locations were not included. COVID-19 data obtained from UEHC included self-reported history and some HCP may have been diagnosed with COVID-19 outside our institution but did not report to UEHC. In addition, information on whether HCP with SARS-CoV-2 were symptomatic was not available. COVID-19 vaccine information for individual HCP was protected by UEHC and was not used in this study. However, vaccine uptake among HCP at UIHC was >90% by September 1, 2021. We did not ascertain whether HCP acquired COVID-19 at work or in the community. Some studies have shown that COVID-19 incidence among HCP is primarily influenced by community incidence and household exposures rather than the workplace. ^{Reference Szajek, Fleisch and Hutter11} We did not include whether an HCP had had patient contact. We did not obtain race data and did not evaluate the COVID-19 incidence among HCP by race.

In conclusion, special infection control strategies including increased air exchanges and stricter PPE and vaccination policies may be needed for HCP in the ED, for those with higher risk job titles, and in areas with low vaccine uptake. COVID-19 among HCP by location became comparable following the availability of COVID-19 vaccines.