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

Abstract

Background 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. Methods 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. Findings 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. Interpretation 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.

Seroprevalence and seroconversion rates to SARS-CoV-2 in interns, residents, and medical doctors in a University Hospital in Bogotá, Colombia

“…The levels of seroprevalence for CLA IgG (2.28%) at the beginning of the study and of seroconversion to this antibody (5.98%) are comparable to those reported in other studies and, overall, higher than those observed in the general population [1][2][3][4][5][6]. In a comparable study in England that followed 200 front line HCW for two weeks, they found that 20% of them seroconverted during the study, but 25% were already seropositive at the beginning of the study [1]. Most likely, the higher numbers in the English study compared with our study are due to the differences in the populations studied (front line workers vs a mixed population of medical doctors).…”

“…During the SARS-CoV-2 pandemic healthcare workers (HCW) have been shown to have an increased risk of infection [1][2][3][4][5][6]. Studies in this population in many parts of the world have shown seroprevalences of between 2.4% and 45%, and in general above that of the general population and varing according to multiple factors [1][2][3][4][5][6]. In asymptomatic HCW, at the peak of the pandemic in England, a global seroprevalence rate of 24.4% was found [7].…”

“…Although retrospective reporting of symptoms may have evocation bias, these findings indicates that, in the context of COVID-19 a relationship can be established between retrospectively reported symptoms and seroprevalence. Seroconversion rates in HCW have been reported in fewer studies and varied between 20-44% in short term followup during high circulation of SARS-CoV-2 [1,8].…”

Clustering and superspreading potential of SARS-CoV-2 infections in Hong Kong

“…For this study we collected information on 1,038 cases identified in Hong Kong up to 28 April. The majority (51.3%, 533/1,038) of SARS-CoV-2 infections confirmed during the study period (23)(24)(25)(26)(27)(28) were associated with at least 1 of 137 clusters. Cases were linked to clusters (≥2 confirmed cases) based on the reported contact histories between cases (Methods).…”

Chest drain aerosol generation in COVID-19 and emission reduction using a simple anti-viral filter

“…Despite implementation of WHO guidance designed to reduce in-hospital spread, 1 nosocomial and HCW infection have remained prominent features of the current COVID-19 pandemic, with 43.5% of UK HCWs becoming seropositive over a 1-month period in one recent study. 2 Better understanding of in-hospital infection sources is therefore urgently needed. Pleural procedures are not currently considered aerosol-generating by the WHO, 1 and special precautions to mitigate against viral transmission and/or to protect HCWs are not currently recommended.…”