This is how long COVID-19 can live airborne

Three months into the Covid-19 pandemic, researchers have identified another key element of the virus’s pathology.

It was previously determined that transmission most reliably occurs between an infected individual six feet or less away from a subject through infectious droplets produced by a sneeze or a cough.

Early Tuesday morning, scientists from the National Institute of Allergy and Infectious Diseases lengthened our data set by determining the approximate length of time that the novel coronavirus remains viable while airborne and atop surfaces.

“A novel human coronavirus that is now named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, China, in late 2019 and is now causing a pandemic. We analyzed the aerosol and surface stability of SARS-CoV-2 and compared it with SARS-CoV-1, the most closely related human coronavirus,” the authors write in the new paper.

Covid-19 fomites remain infectious for at least three hours in aerosols and can remain active on plastic and stainless steel surfaces for roughly three days. On cardboard, the virus remains viable for up to 24 hours. On copper, it takes roughly four hours for the virus to become deactivated. Covid-19 can live on smartphone screens, (assuming they’re composed of glass material) for up to 96 hours or just about four days. 

It should be noted that the pathogen does not retain its full potency for the entire duration of these projected windows. Sixty-six minutes after activated material leaves its host, half of the virus’s fomites lose function while airborne. Another hour and six minutes later, 75% of viral material becomes inactive. 

“The amount of viable virus at the end of the third hour will be down to 12.5%,” explains researcher Neeltje van Doremalen of the NIAID’s Montana facility at Rocky Mountain Laboratories.

All of the findings indexed above are further influenced by two important variables, namely temperature and intervention methods. Room temperature facilitates active fomites the most effectively, and disinfectant products made with at least 60% alcohol deactivates viral agents the quickest. 

“Our results indicate that aerosol and fomite transmission of SARS-CoV-2 is plausible since the virus can remain viable and infectious in aerosols for hours and on surfaces up to days (depending on the inoculum shed). These findings echo those with SARS-CoV-1, in which these forms of transmission were associated with the nosocomial spread and super-spreading events, and they provide information for pandemic mitigation efforts,” the authors conclude in the report.

Be sure to read the full analysis in The New England Journal of Medicine.