Researchers from the National Institute of Health recently released preliminary data on a study to determine how long SARS-CoV-2 (the virus that causes COVID-19) can live on different types of surfaces. Here is a summary of their findings, and what it means for you at home and at work:
SARS-CoV-2 viability in the air and on surfaces
The NIH experiment only measured SARS-CoV-2 in aerosols (a suspension of particles in the atmosphere) for the duration of the 3-hour experiment. In the laboratory conditions SARS-CoV-2 remained aerosolized. However, the current theory on real-world transmission doesn’t point towards aerosolization as an exposure risk, but rather respiratory droplets are the most likely risk for transmission
The same NIH experiment also reported viable virus particles were found on plastic and stainless steel for up to 72 hours after exposure. On copper, SARS-CoV-2 was detectable for up to 4 hours, and on cardboard for up to 24 hours.
What this NIH study did not examine, however, is if SAR-CoV-2 is actually aerosolized in real-world environments. Right now, we only know of another recent study about researchers who went into patients’ rooms and measured where the virus particles were found. They checked surfaces in the room as well as the air. Even though many surface samples were positive (door handles, toilet bowls, sinks), none of the air samples taken were positive for SAR-CoV-2. This study was small (only three patients’ rooms were examined), and it was not possible to sample the entire air volume of the room, however it continues to support the existing belief that SARS-CoV-2 is transmitted mostly through respiratory droplets, not aerosols.
Respiratory droplets are larger particles that do not remain suspended in the air, but instead fall to the air with gravity. You can get infected with respiratory droplets when someone nearby, generally within 6 feet, coughs or sneezes.
What this means for us is that the virus can infect people through the air as respiratory droplets, but we still do not have any evidence that SAR-CoV-2 lingers in the air for long periods of time in an aerosolized form in public. This, of course, may change, as we continue to rapidly study this virus.
Healthcare providers still critically need PPE
There are some invasive medical procedures, such as endotracheal intubation, where aerosolized particles may be created, which further increases the need for our frontline healthcare providers to have adequate access to personal protective equipment (PPE), such as N95 masks and face shields.
Protecting against virus transmission
The potential durability of SAR-CoV-2 highlights the importance of social distancing and for members of the public to stay home as much as possible even more; the respiratory droplets from a person with COVID-19 can remain on surfaces for hours to days.
The best way for non-responders to avoid exposure to COVID-19 is to stay away from public spaces as much as possible: areas where potentially contagious people have been present. You can reduce your time in public by ordering groceries online for curbside pick-up or contact-free delivery to your home, and doing the same with essential medications from the pharmacy. Cancel other public outings, and limit your physical social contact to the people in your home, or a few close friends nearby. Public safety departments should continue to advocate for their communities to stay home and practice social distancing through social media campaigns and public announcements.
Clean the high touch surfaces in your house daily. Countertops, doorknobs, handles, desks, faucets, sinks (and don’t forget your computer, keyboard, and mouse, as many of us work from home!). Any household cleaning product or disinfectant will do the job. Wash your hands regularly and avoid touching your face. Sneeze or cough into a tissue and dispose of it immediately, then wash your hands again. When in doubt, wash your hands. A little soap and water goes a long way.
References:
- N van Doremalen, et al. Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1. The New England Journal of Medicine. DOI: 10.1056/NEJMc2004973 (2020).
