Prevalence of SARS-CoV-2 infection in previously undiagnosed health care workers in New Jersey, at the onset of the U.S. COVID-19 pandemic

BMC Infect Dis. 2020 Nov 16;20(1):853. doi: 10.1186/s12879-020-05587-2.


Background: Healthcare workers (HCW) are presumed to be at increased risk of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection due to occupational exposure to infected patients. However, there has been little epidemiological research to assess these risks.

Methods: We conducted a prospective cohort study of HCW (n = 546) and non-healthcare workers (NHCW; n = 283) with no known prior SARS-CoV-2 infection who were recruited from a large U.S. university and two affiliated university hospitals. In this cross-sectional analysis of data collected at baseline, we examined SARS-CoV-2 infection status (as determined by presence of SARS-CoV-2 RNA in oropharyngeal swabs) by healthcare worker status and role.

Results: At baseline, 41 (5.0%) of the participants tested positive for SARS-CoV-2 infection, of whom 14 (34.2%) reported symptoms. The prevalence of SARS-CoV-2 infection was higher among HCW (7.3%) than in NHCW (0.4%), representing a 7.0% greater absolute risk (95% confidence interval for risk difference 4.7, 9.3%). The majority of infected HCW (62.5%) were nurses. Positive tests increased across the two weeks of cohort recruitment in line with rising confirmed cases in the hospitals and surrounding counties.

Conclusions: Overall, our results demonstrate that HCW had a higher prevalence of SARS-CoV-2 infection than NHCW. Continued follow-up of this cohort will enable us to monitor infection rates and examine risk factors for transmission.

Keywords: COVID-19; Healthcare workers; SARS-CoV-2.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Betacoronavirus*
  • COVID-19
  • Cohort Studies
  • Coronavirus Infections / epidemiology*
  • Cross-Sectional Studies
  • Female
  • Health Personnel*
  • Humans
  • Male
  • Middle Aged
  • New Jersey / epidemiology
  • Occupational Diseases / epidemiology*
  • Occupational Diseases / virology
  • Occupational Exposure* / adverse effects
  • Pandemics
  • Pneumonia, Viral / epidemiology*
  • Prevalence
  • Prospective Studies
  • Risk Factors
  • SARS-CoV-2
  • Time Factors
  • Young Adult