When the COVID-19 pandemic first began, many strange but now familiar scenes began to play out in public: People touching elbows instead of shaking hands, commuters avoiding train handles on their way to work, and office workers wiping down their desks each morning name just a few. But are these actually effective coronavirus protection measures to take? And just how long does the virus survive on surfaces?
Surface-Level Fears
Like several respiratory viruses such as the flu, COVID-19 typically spreads through tiny droplets released from an infected person's coughing, sneezing, and even talking. Just one cough can release 3000 droplets. Once out in the air, the larger particles can land on other people and the surfaces around them, while the smaller ones can linger in the air.
The Imperial College London published a study that showed viral DNA left on an isolated hospital bed rail had managed to spread to 18 other surfaces in the span of only ten hours. These surfaces included waiting room chairs, children's toys in the play area, and door handles. While this research focused on a virus that infects plants instead of COVID-19, it elucidated just how far a virus can spread.
So, How Long Does the Coronavirus Survive on Surfaces?
While the aforementioned research may make you feel a need to panic, the Centers for Disease Control and Prevention (CDC) stated that touching a COVID-contaminated surface and then touching your own face "is not thought to be the main way the virus spreads." The CDC later updated this guidance to state that COVID-19 does spread "very easily" through contaminated aerosol droplets.
Still, the CDC, the World Health Organization, and other health officials have emphasized that sanitizing your hands and frequently touched surfaces are essential to preventing COVID-19's spread. In the case of school, restaurant, and public place reopenings, the CDC does still emphasize that intensified sanitizing of surfaces is still needed. Essentially, while it's not exactly clear how many COVID-19 cases are due to transmission through contaminated surfaces, experts still advise that we exercise caution.
Coronaviruses are known to be resilient in terms of where they can survive. A National Institutes of Health (NIH) study found that the coronavirus can survive on plastic and metal for up to two or three days without proper disinfection. A more recent study by microbiologists in Beijing found that it can survive and remain infectious on steel, glass, latex, and ceramics for up to seven days. In low temperatures, another study found that it can even linger for as long as 28 days.
How To Clean the Coronavirus off of Surfaces
The NIH researchers did find that copper surfaces tend to kill the virus in approximately four hours. If you want to learn more about why copper works so well against the coronavirus, check out this article. While impressive, four hours is still quite long. Luckily, there's a faster option.
Research shows that disinfecting surfaces with 62 to 71% alcohol, 0.5% hydrogen peroxide bleach, or household bleach with 0.1% sodium hypochlorite can inactivate coronaviruses within 60 seconds. Humidity and high temperatures also seem to help in causing the virus to die quicker. The US Environmental Protection Agency (EPA) has published a list of disinfectants that work well against the coronavirus, which you can see here.
Beyond these measures, ultraviolet light is also considered a valid way to disinfect surfaces. But it's not recommended for use on human skin.
Air is a Much More Valid Concern
Perhaps more importantly than their findings on surfaces, the NIH study did also discover that coronavirus droplets can survive for as long as three hours after being coughed out into the air. And the smaller the droplet, the longer they can linger — aerosols between one to five micrometers in size can stay active for several hours.
Surface studies have caused many people to become paranoid and even exaggerate the risk of COVID-19 transmission through this medium. Emmanuel Goldman, a professor of microbiology, molecular genetics, and biochemistry at the New Jersey Medical School of Rutgers University, had this to say in a response published in The Lancet Infectious Diseases:
"In my opinion, the chance of transmission through inanimate surfaces is very small, and only in instances where an infected person coughs or sneezes on the surface, and someone else touches that surface soon after the cough or sneeze (within 1-2 hours)."
Essentially, it would take the perfect combination of events to occur for a person to become infected with COVID-19 via surfaces. It's also worth noting that the majority of surface studies have focused on how long the coronavirus stays active on surfaces, not if you can catch it from them.
With all this said, it's still better to be safe than sorry. Practice caution when you are out in public. Make sure to wear a face mask or 2-ply neck gaiter. And continue to sanitize your hands and commonly touched surfaces regularly.