Coronavirus Thrives On Hard Flat Surfaces – How long can the new coronavirus live on a surface, like say, a door handle, after someone infected touches it with dirty fingers? A study out this week finds that the virus can survive on hard surfaces such as plastic and stainless steel for up to 72 hours, and on cardboard for up to 24 hours.
“This virus has the capability for remaining viable for days,” says study author, James Lloyd-Smith, an assistant professor of ecology and evolutionary biology at the University of California, Los Angeles, who studies how pathogens emerge.
Although the World Health Organization had previously estimated the survival time on surfaces to be a “few hours to a few days” based on research on other coronaviruses, this is the first study by scientists at a federal laboratory to test the actual virus causing the current pandemic, SARS-CoV-2.
The study is out in preprint form and expected to be published.
Interestingly, some surfaces are less hospitable to SARS-CoV-2. For instance, the virus remained viable on copper for only about four hours.
It’s useful to know how long it can stay alive of course, since the virus can contaminate surfaces when an infected person sneezes or coughs. Virus-laden respiratory droplets can land on doorknobs, elevator buttons, handrails or countertops — and spread the virus to anyone who touches these surfaces subsequently.
To test the survival time of the virus, scientists at the Rocky Mountain Laboratories in Montana, part of the National Institutes of Health, conducted a series of experiments comparing the novel coronavirus with the SARS virus (a similar coronavirus that led to an outbreak back in 2003).
In the lab, “they’d pick up the virus from the surfaces that had been contaminated and then put [the virus] into cell cultures,” he explains. Then the researchers documented whether the virus could infect those cells in the dish. They did this multiple times, for both the viruses, at various time points.
“Big picture, the [two viruses] look very similar to each other in terms of their stability in these environments,” Lloyd-Smith says.
Lloyd-Smith says these findings establish a good ballpark estimate for the survivability of the virus on these surfaces. “In a laboratory experiment the conditions are pretty carefully controlled and constant,” he says. By comparison, “In the real world, conditions fluctuate.” Conditions like temperature, humidity and light vary. So the survivability may vary, too.
For instance, say the virus contaminates a sunny window sill or counter-top — it may not last as long.
“Ultraviolet light can be a really powerful disinfectant and we get a lot of UVA light from the sun” says Daniel Kuritzkes an infectious disease expert at Brigham and Women’s Hospital. “Direct sunlight can help rapidly diminish infectivity of viruses on surfaces,” he says. He was not involved in the new research.
Much is still unknown about the virus’s survivability on other types of surfaces like clothing, or carpeting. Kuritzkes says, based on prior research, it seems that “flat surfaces and hard surfaces are more friendly to viruses than cloth or rough surfaces.”
And how about food? “Food is probably not a major risk factor here,” Kuritzkes says. That’s because most infection from the new coronavirus starts with the respiratory system, not the digestive tract. So infection comes from getting the virus on your hands and then touching your own eyes, nose and mouth.
“Of more concern would be utensils, and plates and cups that might be handled by a large number of people in a cafeteria setting, for example,” he says.
So, what can you do to protect yourself? Well, you’ve likely already heard this. Wash your hands. And, wipe down shared surfaces.