Risk of SARS-CoV-2 transmission by fomites: a clinical observational study in highly infectious COVID-19 patients

BackgroundThe contribution of droplet-contaminated surfaces for virus transmission has been discussed controversially in the context of the current Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) pandemic. Importantly, the risk of fomite-based transmission has not been systematically addressed.MethodsWe initiated this single-center observational study to evaluate whether hospitalized COVID-19 patients can contaminate stainless steel carriers by coughing or intensive moistening with saliva and to assess the risk of SARS-CoV-2 transmission upon detection of viral loads and infectious virus in cell culture. Fifteen hospitalized patients with a high baseline viral load (CT value ≤ 25) shortly after admission were included. We documented clinical and laboratory parameters and used patient samples to perform virus culture, quantitative PCR and virus sequencing.ResultsNasopharyngeal and oropharyngeal swabs of all patients were positive for viral RNA on the day of the study. Infectious SARS-CoV-2 could be isolated from 6 patient swabs (46.2 %). While after coughing, no infectious virus could be recovered, intensive moistening with saliva resulted in successful viral recovery from steel carriers of 5 patients (38.5 %).ConclusionsTransmission of infectious SARS-CoV-2 via fomites is possible upon extensive moistening, but unlikely to occur in real-life scenarios and from droplet-contaminated fomites.