Health

How long does coronavirus stay on surfaces and can they infect you?

The coronavirus can persist for days on surfaces, but you’re more likely to become infected from another person

SeongJoon Cho/Bloomberg via Getty Images

As global cases of covid-19 continue to soar and people with symptoms are expected to be isolated from others, it is no surprise that a growing number of us flinch when we hear someone cough, even if they are 2 metres away – the minimum separation that health officials advise.

Research conducted on the new coronavirus and others similar to it, such as SARS, suggest the virus can spread through particles in the air and via contaminated surfaces. How does this happen? Moreover, how long can the virus survive on surfaces and what can we do to protect ourselves?

Covid-19 is a respiratory illness and is largely spread via droplets in the air, says John Lednicky, a virologist who studies coronaviruses at the University of Florida. These are typically expelled when an infected person coughs or sneezes.

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But speaking also releases droplets. The heavier of these will fall to the ground, but smaller, lighter particles can travel further and linger in the air, and are more likely to infect other people, says Lednicky. “You can inhale those, but they can also come into contact with your eyes,” he says.

Even if you keep your distance, there’s a chance of coming into contact with a virus as you walk through a cloud of expelled particles, says Lednicky. It isn’t clear if this is the case with the new coronavirus, but other, similar viruses can spread this way, he says.

There are other, even less pleasant, ways virus-laden particles can get into the air. The symptoms of the coronavirus can vary, but some people experience diarrhoea. “If you use a flush toilet, you create an aerosol full of infection,” says Lednicky.

This effect is more pronounced than usual with diarrhoea, which can contaminate more of a toilet’s surface. The released aerosols can travel along plumbing and ventilation systems and end up moving through buildings and apartment blocks.

This is how SARS spread through a housing block in Hong Kong in 2003. A 33-year-old man with diarrhoea is thought to have passed the infection to hundreds of other residents of the Amoy Gardens site as a result of “defective U-traps in bathrooms, an amplifying effect of bathroom exhaust fans, a cracked sewer vent pipe… and an aerodynamic effect in a light well to which bathroom windows opened”, the World Health Organization reported at the time.

The new coronavirus has also been found to persist for days on surfaces. Last week, a team led by Vincent Munster at the US National Institute of Allergy and Infectious Diseases in Montana published research suggesting the virus can survive on plastic and stainless steel surfaces for up to 72 hours.

But other research suggests that SARS and MERS, which are similar coronaviruses, can persist on metal, glass and plastic surfaces for up to nine days. And on Monday, the US Centers for Disease Control published a report suggesting traces of the new coronavirus could be present on surfaces for even longer – RNA from the virus was detected on surfaces in the cabins of people who had vacated the Diamond Princess cruise ship 17 days earlier, including those passengers who hadn’t shown symptoms.

This doesn’t necessarily mean these virus particles could still infect other people, says Lednicky. On the one hand, virus particles coughed or sneezed out may be covered in a protective layer of mucus that helps them survive. But plenty of other factors also come into play. Ultraviolet light can destroy the ability of some viruses to reinfect people, for example. And heat and humidity can also inactivate viruses.

So, is it worth trying to disinfect your online shopping when it arrives at your home? Lednicky doesn’t think so. Most household cleaning products won’t kill coronaviruses, he says. And even if you use a product that does, you’re unlikely to be able to clean every nook and cranny of, for example, a bunch of grapes. It is more practical to practise social distancing and good personal hygiene, he says.

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