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

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.

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.

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.

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.

Authors: Reina S Sikkema, Suzan Pas, David F. Nieuwenhuijse, Aine O'Toole, Jaco Verweij, Anne van der Linden, Irina Chestakova, Claudia Schapendonk, Mark R Pronk, Pascal Lexmond, Theo Bestebroer, Ronald J Overmars, Stefan van Nieuwkoop, Wouter van den Bijllaardt, Robbert G. Bentvelsen, Miranda M.L. van Rijen, Anton G.M. Buiting, Anne J.G. van Oudheusden, Bram M. Diederen, Anneke M.C. Bergmans, Annemiek van der Eijk, Richard Molenkamp, Andrew Rambaut, Aura Timen, Jan A.J.W. Kluytmans, Bas B. Oude Munnink, Marjolein Kluytmans, Marion P.G. Koopmans