Coronavirus may survive in the air for three hours and on surfaces for up to three days

Coronavirus could survive in the air for up to three hours, suggests a study published on Tuesday in a top medical journal.

The research, published in the New England Medical Journal, emphasises how important it is for people to isolate themselves to slow the spread of the virus.

If the findings are confirmed, people’s risk of infection rises beyond that of being coughed or sneezed on, or touching contaminated surfaces and transferring the virus to their mouth, nose or eyes.

This would be a greater risk for medical staff at the frontline of the pandemic.

The study found that the virus, when suspended in droplets of five micrometers or less (aerosols), could stay in the air for up to three hours (the length of the experiment), before dropping on to surfaces.

The scientists also found that plastic and steel surfaces were likely to have longer contamination of the virus than cardboard, though it may survive on cardboard packages for up to 24 hours.

They found it could survive for up to three days on plastic and up to two days on steel, which is why cleaning and disinfecting surfaces regularly is a priority. Virus contamination on copper surfaces lasted for up to four hours.

On all surfaces the amount of “viable virus” fell fast with time.

Scientists from the US's National Institutes of Health (NIH) “attempted to mimic virus being deposited from an infected person on to everyday surfaces in a household or hospital setting, such as through coughing or touching objects”, the NIH said in a press release.

The research team compared the coronavirus, known as Sars-CoV-2, to Sars-CoV-1 (the original Sars virus).

“We found that the stability of Sars-CoV-2 was similar to that of Sars-CoV-1 under the experimental circumstances tested.”

Why, then, is Sars-CoV-2 resulting in more cases?

“Emerging evidence suggests that people infected with Sars-CoV-2 might be spreading the virus without recognising, or prior to recognising, symptoms," said the NIH.

“This would make disease control measures that were effective against Sars-CoV-1 less effective against its successor.”

Sars infected more than 8,000 people in 2002 and 2003, and was “eradicated by extensive contact tracing and case isolation measures”, the NIH reported. No cases have been reported since 2004.

“In contrast to Sars-CoV-1, most secondary cases of virus transmission of Sars-CoV-2 appear to be occurring in community settings rather than in health-care settings,” it said.