Risk for Acquiring Coronavirus Disease Illness among Emergency Medical Service Personnel Exposed to Aerosol-Generating Procedures

Abstract

We investigated the risk of coronavirus disease (COVID-19)- patients transmitting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to emergency medical service (EMS) providers, stratified by aerosol-generating procedures (AGP), in King County, Washington, USA, during February 16-July 31, 2020. We conducted a retrospective cohort investigation using a statewide COVID-19 registry and identified 1,115 encounters, 182 with ≥1 AGP. Overall, COVID-19 incidence among EMS personnel was 0.57 infections/10,000 person-days. Incidence per 10,000 person-days did not differ whether or not infection was attributed to a COVID-19 patient encounter (0.28 vs. 0.59; p>0.05). The 1 case attributed to a COVID-19 patient encounter occurred within an at-risk period and involved an AGP. We observed a very low risk for COVID-19 infection attributable to patient encounters among EMS first responders, supporting clinical strategies that maintain established practices for treating patients in emergency conditions.

Keywords: COVID-19; SARS-COV-2; aerosol transmission; aerosol-generating procedures; cardiac arrest; coronavirus disease; emergency medical services; emergency treatment; health occupations; medical first responders; public health; public health readiness; respiratory infections; severe acute respiratory syndrome coronavirus 2; viruses; zoonoses.

Figure 1

Examples of classification of EMS provider person-days at risk within 2–14 d after COVID-19 patient encounters, King County, Washington, February 16–July 31, 2020. The boxes correspond to the number of person-days an emergency medical services provider contributes to each mutually exclusive risk group. The first row (provider A) demonstrates a COVID-19 patient encounter without an AGP. The provider is classified at risk for COVID-19 transmission because of a patient treated without AGP within 2–14 d after encounter. After the incubation window ends, the EMS provider transitions back to person-days classification of COVID-19 patient outside the incubation period (cohort 3). The second row (provider B) demonstrates classification of person-days from COVID-19 patient without AGP and then with AGP. Person-days transitions from COVID-19 patient encounter without AGP (cohort 2) to patient encounter with AGP (cohort 1). The example illustrates the classification hierarchy that classified the patient into the AGP incubation period when a provider had overlap of person-days following distinct encounters caring for COVID-19 patients without an AGP and then with an AGP. After the incubation window, the EMS provider will transition back to person-days classification of COVID-19 patient outside the incubation period (group 3). AGP, aerosol-generating procedure; COVID-19, coronavirus disease; EMS, emergency medical service.

Figure 2

Flow diagram of emergency medical service provider encounters with COVID-19 patients and person-days at risk for transmission, King County, Washington, February 16–July 31, 2020. Individual provider’s person-days may transition among cohorts 1–3. AGP, aerosol generating procedure; COVID-19, coronavirus disease; EMS, emergency medical services.