Chance of catching Covid-19 from surfaces less than previously thought, scientists claim
The chance of catching coronavirus from doorknobs and light switches may be less than previously thought, scientists have suggested.
At the start of the pandemic governments across the world began emphasising the need to clean surfaces to kill off any chance of infection.
But recently, some scientists have pointed to evidence which suggests the chance of catching Covid-19 from a surface is very low.
Dr Andrew Preston, reader in Microbial Pathogenesis at the University of Bath, told ITV News that early on in the pandemic "there was lots of concern" over contaminated surfaces.
But he pointed out the studies the concern was based on used high doses of the virus in lab settings and said just because it was present did not mean it was still infectious.
He said: "More recently, there have been several articles questioning the relevance of these studies and suggesting risk from surfaces is low."
Transmission of the virus was much more likely from close contact between people indoor situations because the small droplets that travel from noses and mouths can go much further than the large droplets which can be left on surfaces, Dr Preston said.
He said just because the chance of catching the virus was low doesn't mean it should be ignored.
He pointed out it could still be a significant risk in some situations: "For example, a tube train carriage will have a high turnover of people.
"One of the poles or handles that people use could be touched by numerous people in a short space of time.
"So hand washing must remain a central part of the preventative measures against Covid."
Monica Gandi, a professor of medicine at the University of California expressed a similar view when she told the science website Nautilus there had been "a lot of fear" about transmission through surfaces at the start of the pandemic.
But she said the overwhelming way in which people catch coronavirus is by being exposed to an infected person's droplets from their nose and mouth, adding: "It's not through surfaces."
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Emanuel Goldman, a microbiologist from the US, recently highlighted how most of the evidence supporting fomite transmission (the scientific phrase for catching the virus from an inanimate surface) of coronavirus was not applicable to real-world situations.
In an article published in the Lancet he said: "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."
He highlighted studies that used high concentrations of the virus in lab settings showed it was still present for up to six days, but that this couldn't be replicated in real life situations where surface amounts of the virus would be "several orders of magnitude smaller".
"In a study in which the authors tried to mimic actual conditions in which a surface might be contaminated by a patient, no viable SARS-CoV was detected on surfaces," he said
He added: "I do not disagree with erring on the side of caution, but this can go to extremes not justified by the data.
"Although periodically disinfecting surfaces and use of gloves are reasonable precautions especially in hospitals, I believe that fomites that have not been in contact with an infected carrier for many hours do not pose a measurable risk of transmission in non-hospital settings."
Mr Goldman pointed out in his research the chance of fomite infection was at its highest immediately after the virus has spread onto the surface.
A core part of the UK government's advice to businesses and local authorities has been to clean surfaces after they've been used by a customer.
Billions of pounds have been spent on disinfectant with mass cleaning regimes now in place in all pubs and restaurants.
Dr Preston said this was still a good tactic that should be deployed as much as possible.
He said: "Hand washing is not a great imposition, it doesn’t really cost and its certainly not a loss of civil liberty compared to lockdowns and other restrictions, so an easy win to achieve.
"Yes, there are other considerable costs associated with the enhanced cleaning involved with dealing with surface contamination.
"But, it’s really quite nice to go to a restaurant to find a clean table, rather than having it smeared with the previous customers’ meals.
"Or to have pub table that doesn’t feel like it’s been coated in treacle. Anecdotally, public toilets have never been in better condition."
The government's advice says: "Surfaces and belongings can be contaminated with Covid-19 when people who are infectious cough or sneeze or touch them.
"Transmission of Covid-19 can occur when someone else then touches the contaminated surface or item.
"The person may become infected if they touch their nose, eyes or mouth with a contaminated hand or object.
"Increased frequency of cleaning of general room surfaces reduces the presence of the virus and the risk of contact."
Mr Preston added: "A focus on basic hygiene will have other benefits in terms of other infections long beyond Covid-19.”