In a prospective cohort study of high-risk front-line health care workers (HCWs) in a UK hospital, 44% showed evidence of SARS-CoV-2 infection either by reverse transcription polymerase chain reaction (RT-PCR) or serology, according to results published in The Lancet.
Researchers enrolled 200 patient-facing staff between 26 March 2020 and 8 April 2020 for the SARS-CoV-2 Acquisition in Frontline Healthcare Workers—Evaluation to inform Response study in an acute NHS hospital trust in London.
They collected nasopharyngeal swabs for RT-PCR twice per week, symptom data and blood samples monthly for high-sensitivity serology assays (enzyme-linked immunosorbent assay and flow cytometry for spike glycoprotein).
Total 87 (44%) of the 200 HCWs had evidence of SARS-CoV-2 infection at any time point, detected either by serology or RT-PCR.
Of the 200, 181 gave a valid blood sample at two time points, and 82 (45%) were seropositive after one month: 36/181 (20%) seroconverted during the study and 46/181 (25%) were already seropositive at study entry.
Meanwhile, 42 (21%) of 200 HCWs tested positive for SARS-CoV-2 by RT-PCR in at least one swab. Twenty (48%) reported symptoms within seven days of the positive test, which were consistent with Public Health England's COVID-19 case definition, and 16 (38%) did not report any symptoms in the same time frame.
The median age of study participants was 34 (interquartile range, 29-44) years. There was a trend towards a higher infection rate in participants under 30 years (31 [55%] of 56 positive) compared with those older than 50 years (10 [33%] of 30 positive), with a reduction in log odds of positivity by 0.035 per year (P=.0199).
The mean duration of detection of SARS-CoV-2 RNA by RT-PCR was 12.9 days (first positive to last positive swab; 95% CI, 9.4-17.3). The longest observed duration of SARS-CoV-2 detection was 29 days.
The findings highlight the "urgent need" for better strategies to protect HCWs and patients from nosocomial transmission of COVID-19, the authors said.
Houlihan CF, Vora N, Byrne T, Lewer D, Kelly G, Heaney J, Gandhi S, Spyer MJ, Beale R, Cherepanov P, Moore D, Gilson R, Gamblin S, Kassiotis G, McCoy LE, Swanton C, Hayward A, Nastouli E; SAFER Investigators. Pandemic peak SARS-CoV-2 infection and seroconversion rates in London frontline health-care workers. Lancet. 2020 Jul 9 [Epub ahead of print]. doi: 10.1016/S0140-6736(20)31484-7. PMID: 32653078. Full text.
This article originally appeared on Univadis, part of the Medscape Professional Network.
