SARS-CoV-2 virus and antibodies in front-line Health Care Workers in an acute hospital in London: preliminary results from a longitudinal study


Catherine Houlihan, Nina Vora, Thomas Byrne, Dan Lewer, Judith Heaney, David A Moore, Rebecca Matthews, Sajida Adam, Louise Enfield, Abigail Severn, Angela McBride, Moira Jane Spyer, Rupert Beale, Peter Cherepanov, Kathleen Gaertner, Maryam Shahmanesh, – The SAFER Field Study Team, Kevin Ng, Georgina Cornish, Naomi Walker, Susan Michie, Ed Manley, Fabiana Lorencatto, – The Crick-COVID-Consortium, Richard Gilson, Sonia Gandhi, Steve Gamblin, George Kassiotis, Laura McCoy, Charles Swanton, Andrew Hayward, Eleni Nastouli


SARS-CoV-2 infection in Healthcare Workers (HCWs) is a public health concern during the pandemic. Little description has been made of their antibody response over time in the presence or absence detectable SARS-CoV-2 RNA and of symptoms. We followed a cohort of patient-facing HCWs at an acute hospital in London to measure seroconversion and RNA detection at the peak of the pandemic in London.


We enrolled 200 front-line HCWs between 26 March and 8 April 2020 and collected twice-weekly self-administered nose and throat swabs and monthly blood samples. Baseline and regular symptom data were also collected. Swabs were tested for SARS-CoV-2 RNA by polymerase chain reaction, and serum for IgM, IgA and IgG antibodies to the virus spike protein by enzyme-linked immunosorbent assay and flow cytometry.


We enrolled HCWs with a variety of roles who worked in areas where COVID-19 patients were admitted and cared for. During the first month of observation, 42/200 (21%) HCWs were PCR positive in at least one nose and throat swab. Only 8/42 HCW (19%) who were PCR positive during the study period had symptoms that met the current case definition. Of 181 HCWs who provided enrollment and follow-up blood samples, 82/181 (45.3%) were seropositive; 36/181 (19.9%) seroconverted during the study and 46/181 (25.4%) were seropositive at both time points. In 33 HCWs who had positive serology at baseline but were PCR negative, 32 remained PCR negative throughout follow-up. One HCW had a PCR positive swab six days after enrollment, likely representing a waning infection.


The extremely high seropositivity and RNA detection in this cohort of front-line HCWs who worked during the peak of the pandemic brings policies to protect staff and patients in the hospital environment into acute focus. Our findings have implications for planning for the expected second wave and for future vaccination roll out campaigns in similar settings. The further evidence of asymptomatic SARS-CoV-2 infection indicates that asymptomatic surveillance of HCWs is essential while our study sets the foundations to answer pertinent questions around the duration of protective immune response and the risk of re-infection.

Overview of SARS-COV-2 studies seroprevalence in context of the worldwide  COVID-19 pandemie. You can register a study here: Contribute
@serohub on Twitter
hzi-braunschweig/serohub on GitHub