Coronavirus: 4 studies explain what you need to know about COVID-19 sticking to surfaces
"The virus can clearly survive for many hours on surfaces."
As the coronavirus pandemic takes over our lives, it's hard to draw the line between being worried about contracting it from literally anything, and understanding where the virus truly hides.
And if you are social distancing or self-isolating at home, your reliance on delivered goods is likely through the roof. Which prompts a question: Can the coronavirus be spread via delivery packaging?
Research on how the virus spreads is complicated, and still very much a work-in-progress. But these four, preliminary studies shine a light on how SARS-CoV-2, the virus that causes COVID-29, sticks to surfaces, and how it may travel through the air.
Hide and seek
According to a study published in The New England Journal of Medicine on Tuesday March 17, the SARS-CoV-2 virus can live from hours to days both in the air and on surfaces.
Researchers compared the virus SARS-CoV-1 with its similar, brother virus SARS-CoV-2. The researchers put the two viruses through 10 experimental conditions, comparing how they behaved in aerosols, and on plastic, stainless steel, copper, and cardboard.
Their results suggest SARS-CoV-2 was detectable:
- On copper up to four hours
- On cardboard up to 24 hours
- On plastic and stainless steel up to two to three days
Both viruses did decay exponentially on all the surfaces, so although it lived, a lot less of it did.
It is important to note that this experiment was done in a lab, and a lab is nothing like the outside world, where conditions can't be rigorously controlled. But the findings do suggest that people may acquire the virus after touching contaminated objects.
“The virus can clearly survive for many hours on surfaces," Linsey Marr, professor in Civil and Environmental Engineering at Virginia Tech, tells Inverse.
"Even if someone has not touched that surface, it may be contaminated with droplets from an infected person, and if you touch the surface, you can potentially pick up the virus and transfer it to your eyes, nose, or mouth."
The findings gibe with another study published earlier this month in the Journal of Hospital Infection. In this study, the researchers looked at how the viruses that cause SARS, MERS, and HCoV — all coronaviruses — persist on surfaces, from wood to PVC, to latex.
Across the board, coronaviruses similar to SARS-CoV-2 may be able to live on surfaces for more than a week, the findings suggest.
“Human coronaviruses can remain infectious on inanimate surfaces at room temperature for up to 9 days. At a temperature of 30°C or more the duration of persistence is shorter.”
Together, the studies suggest that SARS-CoV-2 behaves in a similar way to other coronaviruses when it is on different surfaces. It also hints at why researchers are now suggesting that asymptomatic carriers — people who have come into contact with the virus but show no symptoms of COVID-19 — may be the secret silent spreaders of the virus.
Is the coronavirus airborne?
The March 17 NEJM study also looked at aerosols, which means droplets of liquid smaller than 5 micrometers that can hang in the air.
The researchers show that the novel coronavirus can remain in aerosols (under laboratory conditions) for up to three hours.
Aerosols with the properties tested usually stay suspended in air for up to an hour. After that, they fall onto whatever surface is below.
But it is important to note that while these results suggest the virus can remain airborne for a time in aerosols, it appears not to linger in large enough volumes to spread via air unless you are in the immediate vicinity of an infected person at the same time. This is in contrast to another virus, measles, which can infect someone via airborne virus even after the infectious person has left the vicinity.
“This is not evidence of aerosol transmission,” Neeltje van Doremalen, a coauthor of the study, explained on Twitter before the article was published.
“I don’t think it is normally transmitted via aerosols. But sometimes, health care workers perform aerosol-producing procedures, like intubation. In that situation, it could be important to be aware of viability in aerosols,” van Doremalen explained.
Ultimately, the study "is not evidence of airborne transmission via aerosols — it is evidence for the potential of airborne transmission. It reinforces the importance of airborne precautions,” Don Milton, professor of Environmental Health at University of Maryland, tweeted in response to the findings.
Marr explains that if the virus is contained in aerosol droplets small enough to remain aloft for more than an hour, then the highest chance of transmission happens if you inhale these tiny droplets near the infected person.
“Imagine a puff of cigarette smoke or a breath cloud on a cold day,” Marr says.
That means no one should assume that close-range contamination only occurs if droplets land on the eyes, nostrils, lips, or other exposed skin. You may also be able to breathe in the virus via these droplets, she says.
"I'm aware of other data that is being prepared for publication that will also support these findings," Milton tells Inverse.
"People need to know that there's a risk of airborne transmission by viral aerosols that can be in the air we breathe," he says.
"And, everyone needs to know and that there are simple things to do to reduce that risk."
Coming into land
Another study published during the first week of March in JAMA zoomed in on three people with COVID-19 in isolation in centers in Singapore. The researchers took surface environmental samples of 26 different sites around the patients.
Although the air was clear, the environment around the people with coronavirus did show signs of contamination with the virus.
For example, the toilet bowl and sink samples tested positive for the virus. Samples from air vents tested positive too, once again suggesting that virus encased in tiny droplets may travel through air.
Commenting on the study, van Doremalen tweeted:
In a fourth study, published on March 10 on the preprint server bioRxiv (this means it has not yet been peer reviewed) looked at how aerosols gathered in both public areas and two hospitals, Renmin Hospital of Wuhan University, and Wuchang Fangcang Field Hospital, both in Wuhan, China.
Across the 35 aerosol samples tested, researchers found the virus did exist in aerosol form, but in most cases it was in very low amounts in the air. Overall, the findings confirm aerosol-borne transmission as a reason for surface contamination.
Interestingly, and worryingly, this research also suggests that the virus may become airborne after it has landed on a surface. This may happen, the researchers suggest, when a member of medical staff removes contaminated gear in the staff room, for example.
In the hospitals, the areas with the most contamination appeared to be the "patient mobile toilet room." In fact, virus contamination may come from aerosolization from an infected person's excrement, which fits with the Singaporean study's finding of high surface contamination in patients' bathrooms. The results are extremely preliminary, however, and more research is needed to confirm the findings.
While compelling, these four studies do not change the fact that researchers just do not have enough data to make conclusions about how COVID-19 spreads.
But they do offer an idea of how the virus may transfer from surfaces and aerosols, and hint at a viable way to tackle the problem. In all of these studies, adequate disinfection of surfaces was enough to eliminate the virus entirely.
As research on the virus continues, the results also speak to the importance of social distancing as an effective strategy to fight the spread of the virus, as well as maintaining good hand hygiene, and disinfecting all surfaces regularly.
These are the standard precautions for viruses, Milton says. Stay 6 feet away from other people, open windows and increase ventilation in homes and cars, and avoid crowds and large gatherings.
And as for surgical masks? They help more than they hinder in certain cases, he says.
"Putting surgical face masks on cases [that is people confirmed to have the virus] also reduces shedding into aerosols by about two-thirds in the laboratory. That is not great but it's not nothing either. So, putting surgical masks on cases might reduce large droplet and aerosol risk," Milton says.