The virus that causes COVID-19 can survive for nearly a month in cooler, dark conditions on some nonporous surfaces such as glass and money in controlled laboratory conditions, according to a study published Monday that notes that the primary source of spread still appears to be through airborne aerosols and droplets caused by talking, singing, breathing or laughing.
The study, completed by experts at the Australian Centre for Disease Preparedness, and published in “Virology Journal,” found that the virus was detectable after 28 days on surfaces such as glass, stainless steel, paper and polymer banknotes in lab experiments at room temperature — 68 degrees Fahrenheit.
The authors of the study wrote that the findings are important because phones, ATMS and other high-touch surfaces may not be regularly cleaned and therefore pose risks for transmission.
The experts concluded that surface or “fomite” transmission could play some role in the spread of COVID-19, though the degree is unknown.
“While the primary spread of SARS-CoV-2 appears to be via aerosols and respiratory droplets, fomites may also be an important contributor in transmission of the virus,” the authors wrote.
The study also found the virus is less likely to survive in higher temperatures, a finding confirmed by other studies.
At 86 degrees, the virus was detectable on most of those surfaces for only seven days but it was detected for 21 days on paper notes.
At 104 degrees, the virus was not detected past 48 hours for all surfaces tested.
“Temperature and humidity are both critical factors in viral survivability with an increase in either being detrimental to virus survival,” the authors wrote.
Other experts noted that studies that look at how long the virus can stay on various surfaces are tightly controlled and do not mirror real-life conditions. For example, the experiments in the Australian study were completed in the dark to negate any effects of UV light, which can kill COVID-19.
Previous studies have found virus on surfaces but did not determine whether it was live or inactive virus.
The new study, which looked at virus culture, showed the virus can be detectable and cultured after several days or weeks, which is “disconcerting,” said Peter Katona, chairman of the Infection Control Working Group at UCLA.
But it doesn’t answer whether the virus is still transmissible, he added.
“It’s a step in the right direction,” he said.
“Now we know that they’re viable virus particles. And that’s definitely a help but it doesn’t tell you how much you need to be significant. … The fact that virus on stainless steel is culturable in 28 days, does that mean in 28 days it was still transmissible? That’s the key question and this study did not answer that,” he said.
He added he wouldn’t use the study to inform real-world policies yet, and there’s not enough data to determine what role surface transmission plays in COVID-19 spread.
“We don’t understand that very well at all. We don’t know how important that is. We don’t know how much virus it takes to do that,” he said.
The Centers for Disease Control and Prevention (CDC) states that the most important mode of transmission is from person-to-person.
It “may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this isn’t thought to be the main way the virus spreads,” the CDC said in May guidance.
Still, experts contend that it’s important to frequently wash your hands and avoid touching your eyes, nose or mouth.
“Does the virus that causes Covid stay infectious on surfaces for a long time? Yes. Does it sometimes infect that way? Almost certainly. Should we wash our hands before we touch our face if our hands are possibly contaminated. Definitely,” tweeted former CDC Director Tom Frieden.
Does the virus that causes Covid stay infectious on surfaces for a long time? Yes. Does it sometimes infect that way? Almost certainly. Should we wash our hands before we touch our face if our hands are possibly contaminated. Definitely.
— Dr. Tom Frieden (@DrTomFrieden) October 12, 2020