"As an exception during this period of health crisis, some of the publications mentioned are at the time of writing still in pre-publication, undergoing peer review and subject to change. The results of this pre-print study should be interpreted with utmost caution."
Almost one in four asymptomatic health care workers in one hospital trust tested positive for COVID-19 antibodies, a pre-print study published on medRxiv has shown.
Researchers performed a cross-sectional study recruiting 554 health care workers from University Hospitals Birmingham NHS Foundation Trust (UHBFT) who were at work and asymptomatic. Participants were tested for current infection with SARS-CoV-2 by nasopharyngeal swab for real-time polymerase chain reaction and for seroconversion by the measurement of anti-SARS-CoV-2 spike glycoprotein antibodies by enzyme-linked immunosorbent assay. Results were interpreted in the context of previous, self-reported symptoms of illness consistent with COVID-19.
The point prevalence of infection with SARS-CoV-2, determined by the detection of SARS-CoV-2 RNA on nasopharnygeal swab, was 2.39 per cent (n=13/544).
Serum was available on 516 participants. The overall rate of seroconversion in the cohort was 24.4 per cent (n=126/516). Individuals who had previously experienced a symptomatic illness consistent with COVID-19 had significantly greater seroconversion rates than those who had remained asymptomatic (37.5% vs 17.1%; χ2=21.1034; P<0.0001).
In the week preceding peak COVID-19-related mortality at UHBFT, seroconversion rates among those who were reporting symptomatic illnesses peaked at 77.8 per cent.
Prior symptomatic illness generated quantitatively higher antibody responses than asymptomatic seroconversion. Seroconversion rates were highest among those working in housekeeping (34.5%), acute medicine (33.3%) and general internal medicine (30.3%) with lower rates observed in participants working in intensive care (14.8%) and emergency medicine (13.3%).
The identification that the potential for seroconversion in health care workers can associate differentially with certain hospital departments may inform future infection control and occupational health practices, the authors said.
