A meta-analysis presented at this year's ESCMID Conference on Coronavirus Diseases (ECCVID) shows that 40% of healthcare workers (HCW) who tested positive for COVID-19 were asymptomatic, raising the risk of silent transmission in healthcare settings.
The authors systematically reviewed preprint and peer-reviewed published articles reporting the prevalence of COVID-19 and evaluating the risk factors, clinical characteristics, and clinical outcomes among HCW.
A total of 97 studies, including 230,398 HCW across 24 countries, met the inclusion criteria. From the screened HCW using PCR testing and the presence of antibodies, the estimated prevalence of SARS-CoV-2 infection was 11% and 7%, respectively.
Almost half (48%) of those testing positive for COVID-19 were nurses, followed by physicians (25%) and other HCW (23%).
Most of the affected HCW were working in regular/non-surgical/non-COVID wards during screening (43%), followed by 24% in the operating room, 16% in the emergency room and 9% in ICU, with 29% reporting 'other' locations.
"Loss of taste and smell (anosmia), fever and muscle pain were identified as the only symptoms significantly associated with SARS-CoV-2 positivity among HCW," explained study co-author Dr Taulant Muka, University Of Bern, Switzerland.
Pooled data from 15 studies showed, that among RT-PCR positive HCW, 40% did not show symptoms at time of diagnosis.
One in 20 (5%) of the COVID-19-positive HCW developed severe clinical complications, and one in 200 (0.5%) died.
"Because we might miss a large proportion of COVID-19 cases if screening targets only symptomatic HCW, universal screening for all exposed HCW regardless of symptoms should be the standard strategy. While more research is needed to understand specific interventions that can help reducing SARS-CoV-2 infection among healthcare personnel, it is clear that providing healthcare workers with adequate personal protective equipment and training is essential," said study co-author Prof Oscar H Franco.
The study is being published in The American Journal of Epidemiology.