Screening of healthcare workers for SARS-CoV-2 highlights the role of asymptomatic carriage in COVID-19 transmission

Rivett, L.; Sridhar, S.; Sparkes, D.; Routledge, M.; Jones, N. K.; Forrest, S.; Young, J.; Pereira-Dias, J.; Hamilton, W. L.; Ferris, M.; Torok, E.; Meredith, L.; Bioresource Collaboration, T. C.-N. C.; Curran, M.; Fuller, S.; Chaudhry, A.; Shaw, A.; Samsworth, R. J.; Bradley, J. R.; Dougan, G.; Smith, K. G. C.; Lehner, P. J.; Matheson, N. J.; Wright, G.; Goodfellow, I.; Baker, S.; Weekes, M. P.

Significant differences exist in the availability of healthcare worker (HCW) SARS-CoV-2 testing between countries, and existing programmes focus on screening symptomatic rather than asymptomatic staff. Over a 3-week period (April 2020), 1,032 asymptomatic HCWs were screened for SARS-CoV-2 in a large UK teaching hospital. Symptomatic staff and symptomatic household contacts were additionally tested. Real-time RT-PCR was used to detect viral RNA from a throat+nose self-swab. 3% of HCWs in the asymptomatic screening group tested positive for SARS-CoV-2. 17/30 (57%) were truly asymptomatic/pauci-symptomatic. 12/30 (40%) had experienced symptoms compatible with coronavirus disease 2019 (COVID-19) >7 days prior to testing, most self-isolating, returning well. Clusters of HCW infection were discovered on two independent wards. Viral genome sequencing showed that the majority of HCWs had the dominant lineage B{middle dot}1. Our data demonstrates the utility of comprehensive screening of HCWs with minimal or no symptoms. This approach will be critical for protecting patients and hospital staff.