Environmental contamination risk from asymptomatic SARS-CoV-2 infection

There is emerging evidence that contaminated surfaces play a role in the transmission of the SARS-CoV-2 virus that causes COVID-19.

This is in line with the diverse transmission routes of other respiratory viruses such as SARS-CoV-1 and influenza. One of the key features of SARS-CoV-2 is the documented spread from people with asymptomatic and pre-symptomatic infection. A new study has identified contamination with SARS-CoV-2 surrounding patients with asymptomatic infection.

Environmental sampling was performed around 13 patients with laboratory confirmed SARS-CoV-2 infection. 11 patients had mild symptoms, two patients had no symptoms at all. A total of 44 of 112 (39.3%) surface samples were positive for SARS-CoV-2 by RT-PCR, and air samples were negative. Importantly, four surfaces in the room of a patient without symptoms were found to be contaminated with SARS-CoV-2 RNA. The research team did not attempt to culture SARS-CoV-2 from the surfaces, so it is not clear whether the RNA is from viable virus.

This small but important study illustrates the risk of surface contamination from patients with mild and asymptomatic SARS-CoV-2 infection. It also seems likely that staff with asymptomatic infection will also be contaminating their environment, which creates the risk of contact transmission to patients and other staff. These findings reinforce the need for enhanced cleaning and disinfection during the of the COVID-19 pandemic.