COVID-19 in healthcare workers in three hospitals in the South of the Netherlands, March 2020 (preprint)

Background: Ten days after the first reported case of SARS-CoV-2 infection in the Netherlands, 3.9% of healthcare workers (HCWs) in nine hospitals located in the South of the Netherlands tested positive for SARS-CoV-2 RNA. The extent of nosocomial transmission that contributed to the HCW infections was unknown. Methods: We combined epidemiological data, collected by means of structured interviews of HCWs, with whole genome sequencing (WGS) of SARS-CoV-2 in clinical samples from HCWs and patients in three of nine hospitals that participated in the HCW screening, to perform an in-depth analysis of sources and modes of transmission of SARS -CoV-2 in HCWs and patients. Results: A total of 1,796 out of 12,022 HCWs (15%) of the three participating hospitals were screened, based on clinical symptoms, of whom 96 (5%) tested positive for SARS-CoV-2. We obtained complete genome sequences of 50 HCWs and 18 patients. Most sequences grouped in 3 clusters, with 2 clusters displaying local circulation within the region. The observed patterns are most consistent with multiple introductions into the hospitals through community acquired infections, and local amplification in the community. Conclusions: Although direct transmission in the hospitals cannot be ruled out, the data does not support widespread nosocomial transmission as source of infection in patients or healthcare workers.

SARS-CoV-2 infection in 86 healthcare workers in two Dutch hospitals in March 2020 (preprint)

Background On February 27, 2020, the first patient with COVID-19 was reported in the Netherlands. During the following weeks, nine healthcare workers (HCWs) were diagnosed with COVID-19 in two Dutch teaching hospitals, eight of whom had no history of travel to China or Northern-Italy. A low-threshold screening regimen was implemented to determine the prevalence and clinical presentation of COVID-19 among HCWs in these two hospitals. Methods HCWs who suffered from fever or respiratory symptoms were voluntarily tested for SARS-CoV-2 by real-time reverse-transcriptase PCR on oropharyngeal samples. Structured interviews were conducted to document symptoms for all HCWs with confirmed COVID-19. Findings Thirteen-hundred fifty-three (14%) of 9,705 HCWs employed were tested, 86 (6%) of whom were infected with SARS-CoV-2. Most HCWs suffered from relatively mild disease and only 46 (53%) reported fever. Seventy-nine (92%) HCWs met a case definition of fever and/or coughing and/or shortness of breath. None of the HCWs identified through the screening reported a travel history to China or Northern Italy, and 3 (3%) reported to have been exposed to an inpatient known with COVID-19 prior to the onset of symptoms. Interpretation Within two weeks after the first Dutch case was detected, a substantial proportion of HCWs with fever or respiratory symptoms were infected with SARS-CoV-2, probably caused by acquisition of the virus in the community during the early phase of local spread. The high prevalence of mild clinical presentations, frequently not including fever, asks for less stringent use of the currently recommended case-definition for suspected COVID-19.