Up to 11% of health care workers globally might be infected from SARS-CoV-2

14.09.2020 – Health care workers (HCW) are at the frontline response to the new coronavirus disease 2019 (COVID-19), exposing themselves to a higher risk of acquiring the disease, and subsequently, exposing patients and colleagues. Characterizing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 infection) within health-care workers is critical for designing effective preventive measures to limit the transmission of the virus within a hospital, and from hospitals to the community, and thus achieving optimal control of the pandemic.

An international team of researchers from Bern, Switzerland and Bucaramanga, Colombia conducted a review and meta-analysis of observational studies quantifying SARS-CoV-2 infection in terms of prevalence, risk factors, and prognosis among healthcare workers. The researchers identified ninety-seven studies performed across 24 countries, and including 230,398 participants, that met criteria for inclusion in the analysis. This article is currently in press at the American Journal of Epidemiology.

Among HCW, the global pooled prevalence of SARS-CoV-2 infection based on RT-PCR was 11%, while the pooled prevalence of antibody presence was 7%. Almost half of infected HCW workers (48%) were nurses, followed by physicians (25%) and other HCW. Most of the SARS-CoV-2 positive personnel were working in hospitalization/non-emergency wards during the screenings (43 %), followed by the operating rooms and surgery services (24%).

Authors also found that 40% HCW were asymptomatic at the time of SARS-CoV-2 diagnosis by RT-PCR. While as expected, symptomatic HCW were more likely to test positive than non-symptomatic HCW (19% vs. 7%). Among symptomatic HCW, the most common reported symptoms were fever, cough, myalgia, headache and malaise, but presence of anosmia and fever were identified as the only factors significantly associated with SARS-CoV-2 infection among HCW. Five percent of the COVID-19 positive HCW developed severe disease, and 0.5% died.

Dr Sergio Alejandro Gómez-Ochoa, researcher in the Cardiovascular Foundation of Colombia, Colombia, and first author on the paper, said: “Nurses accounted for the largest number of HCW positive for SARS-CoV-2 infection. This may be explained by the larger time staff nurses usually spend with direct patient care involving tasks performed at the bedside, drug administration, and being the first line of response in case of any patient complications”.

The researchers say that high SARS-CoV-2 infection observed among HCW in hospitalization/non-emergency wards in the current study may suggest a difference in Personal Protective Equipment (PPE) use across settings, which might lead to a higher compliance to this measures in the emergency departments and intensive care units compared to non-COVID-19 wards. Implementation of adequate PPE and training on how to use them among HCW could be critical to reduce transmission of SARS-CoV-2 in a clinical setting.

Dr Taulant Muka, preventive medicine researcher at the Institute of Social and Preventive Medicine (ISPM) University of Bern, Switzerland, and senior author on the paper, said: “HCW protect us, it's time we do our best to protect them from SARS-CoV-2 infection. They represent a population with a very high risk of being infected with SARS-CoV-2, with 5% of infected HCW developing clinical complications. Forty percent of the infected HCW are asymptomatic at the time of diagnosis. This might favour silent transmission to colleagues, patients, family members and their communities if the preventive measures are not implemented. While screening for Covid-19 specific symptoms could be useful in low- and middle-income countries with limited testing capacity, universal screening for all exposed HCW regardless of symptoms should be the standard strategy. We will miss a large proportion of COVID-19 cases if screening targets only symptomatic HCW.

Professor Oscar Franco from the University of Bern, Switzerland, co-author of the paper, said: “Our findings have important implications for policy makers and hospital administrators in better planning of resources to reduce SARS-CoV-2 transmission in hospitals. Yet, further rigorous studies are needed to determine specific interventions that can help reducing SARS-CoV-2 infection among healthcare personnel. This is a key vulnerable population that deserve receiving the best protection equipment, adequate work conditions and training. Policy makers and society should recognise this segment of the population as priority, without their health and wellbeing we won’t able to control this pandemic


Gómez-Ochoa, SA et al. COVID-19 in Healthcare Workers: A Living Systematic Review and Meta-analysis of Prevalence, Risk Factors, Clinical Characteristics, and Outcomes. American Journal of Epidemiology; in Press.

Contact details

Taulant Muka, MD, MPH, PhD
Institute of Social and Preventive Medicine
Tel: +41 31 684 31 44
Mob: +41 (0)787403111
Email: taulant.muka@ispm.unibe.ch