Incidence, Spectrum of Symptoms and Risk Factors for Coronavirus Disease 2019 (COVID-19) among Healthcare Workers - a Prospective Cohort Study

The Coronavirus Disease 2019 (COVID-19) pandemic - caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) - has got significant implications on our daily life, currently dominating the medical agenda of the majority of health-care workers (HCWs). Case fatality rates vary significantly between studies, being alarmingly high in some of those, which probably reflects differences in the susceptibility of affected populations, but also in methods of surveillance, including testing frequency. HCW are at the center of this epidemic, both as care providers to severely-ill patients but also as potentially vulnerable population to acquire the infection due to heavy daily exposure to the virus. The burden of COVID-19 among the HCW population remains largely unknown, although single reports of fatalities have raised concerns among HCW regarding their own safety while caring for COVID-19 patients. In this study, we aim to prospectively assess the incidence of COVID-19, the spectrum of symptoms (including the proportion of oligo- and asymptomatic cases) as well as risk factors for infection among different types of HCW. For this protocol, we define HCW as hospital employees. We will include HCWs from an adult and a pediatric acute care hospital, and HCWs with and without patient contact. Main outcome in these study subjects is COVID-19 seroconversion. Dried blood spots will be collected bi-weekly to document seroconversion during a 4-month observation period; respiratory samples will be taken from symptomatic and non-symptomatic individuals. Data on risk behavior - including adherence to and use of personal protective equipment (PPE) - and on exposures in the hospital and the community will be gathered via an online platform; a daily text message will be sent out asking participants about symptoms compatible with a viral infection. Also, institutional factors such as number of hospitalized COVID-19 patients and availability of PPE will be monitored during the study period. The planned 1000 subjects were fully registered six days after the launch of the study promotion on March 19th and the full baseline sample collection will be completed within 10 days. We expect these findings to help better estimate the burden of SARS-CoV-2 and to better understand risk factors leading to (severe) infection among HCWs. We hypothesize that a significant proportion of seroconverted HCWs does not exhibit any symptoms. Differences in adherence to general hygiene principles, different exposures as well as personal risk factors might explain differences in susceptibility and severity of the disease.