The coronavirus may survive on surfaces for several days, research suggests.
The circulating strain – named Covid-19 – is making headlines all over the world, but was virtually unheard of at the start of the year.
Although known to spread via coughs and sneezes, little was understood about whether the virus “lurks” in the air or on surfaces.
To learn more, scientists from the National Institutes of Health in the US used a nebuliser device to expel the virus into the air, mimicking a cough or sneeze.
Results suggest the “viable virus” could be detected up to three hours later in the air, and up to three days later on plastic and stainless steel.
The findings are yet to be peer reviewed, but experts have called them “sobering” and “scientifically sound”.
Latest coronavirus news, updates and advice
The coronavirus is thought to have emerged at a seafood and live animal market in the Chinese city of Wuhan at the end of last year.
It has since crossed national borders into more than 140 countries, across every inhabited continent.
Since the outbreak was identified, over 169,000 patients have been confirmed worldwide, of whom more than 77,000 have “recovered”, according to John Hopkins University data.
China was once the epicentre of the outbreak, with more than 81,000 confirmed cases.
It has since been “overtaken” by Europe, which has “more reported cases and deaths than the rest of world combined apart from China”.
More than 37,000 people have been tested in the UK, with 1,395 registering as positive. 35 people have died in the UK.
Globally, the death toll has exceeded 6,500.
Can the coronavirus survive on surfaces?
Covid-19 is one strain of the coronavirus class, of which seven are known to infect humans.
Others include four strains that cause the common cold and severe acute respiratory syndrome (Sars).
Covid-19 is thought to be more genetically similar to Sars than any other coronavirus strain, so much so the International Committee on Taxonomy of Viruses calls it “severe acute respiratory syndrome coronavirus 2” (SARS-CoV-2).
Despite their similarities, Covid-19 is proving to be much more serious.
More than 6,500 deaths have been reported in the ongoing pandemic, considerably more than the 774 fatalities that occurred in Sars’ 2002/2003 outbreak.
When it comes to whether Covid-19 survives on hard surfaces, the US Centers for Disease Control and Prevention says it “may be possible a person can get [the virus] by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes”.
It adds, however, that “this is not thought to be the main way the virus spreads”.
In the National Institutes of Health’s research, the team found that Covid-19 and Sars survive for similar lengths of time in the air and on surfaces.
Results suggest the “viable” Covid-19 virus could be detected up to three hours later in the air, up to four hours on copper, up to 24 hours on cardboard, and up to three days on plastic and stainless steel.
The scientists concluded the “greater environmental viability” of Covid-19 does not therefore account for its greater severity over Sars.
They were also quick to point out their results do not suggest patients are catching the virus from the air or contaminated surfaces, with coughs and sneezes the main routes of transmission.
“We're not by any way saying there is aerosolised transmission of the virus, but this work shows the virus stays viable for long periods in those conditions, so it's theoretically possible,” said lead author Dr Neeltje van Doremalen.
The results have been published “preliminarily” at Medrix online, rather than in a peer-reviewed journal.
When peer-reviewed, a panel of scientists not involved in the research weigh in on its strengths and weaknesses.
Nevertheless, several experts said the results appeared valid.
“This is really valuable and sobering evidence,” said Professor Jimmy Whitworth from the London School of Hygiene & Tropical Medicine.
“It gives us numbers and confirms what many of us have been suspecting, which is there may well be an aerosol element to transmission; it is from someone’s cough or sneeze and stays there for a while.
“The advice to wipe down surfaces is important.”
Professor Willem van Schaik from the University of Birmingham agreed, adding: “The preprint on survival of the coronavirus on surfaces is scientifically valid in my opinion.
“Coronaviruses appear to remain viable on surfaces for longer periods of time than the flu viruses, which may contribute to its rapid spread.
“The implications of this are very clear: people should wash their hands very frequently (whenever they enter or leave their home/work etc) and should try to minimise touching their faces (and this is extremely difficult to do).”
Professor William Keevil from the University of Southampton noted many surfaces are difficult to avoid, like door handles and touchscreens in public places.
“[The study] re-emphasises the need for good personal hygiene such as washing hands rigorously throughout the day, or using an alcohol hand gel, and avoid touching the eyes, nose and mouth,” he said.
Dr Simon Clarke from the University of Reading noted, however, that the research looked at “artificial aerosols”.
It is therefore is not a “measure of real people who are sneezing or coughing”.
What is Covid-19?
Most of those who initially caught Covid-19 worked at, or visited, a market in Wuhan.
The virus mainly spreads via infected droplets that have been coughed or sneezed out by a patient.
There is also evidence it may be transmitted in faeces and urine.
Early data suggests four out of five cases are mild, with a patient’s immune system naturally fighting off the virus.
In severe cases, pneumonia can come about when the infection causes the alveoli (air sacs) in the lungs to become inflamed and filled with fluid or pus.
The lungs then struggle to draw in air, resulting in reduced oxygen in the bloodstream.
Those requiring hospitalisation are offered “supportive care”, like ventilation, while their immune system gets to work.
The vast majority of deaths are occurring among the elderly or those with underlying health issues.