I don’t know about you, but I am disappointed that scientists still don’t know exactly how people become infected with COVID-19. Brand new research from Australia and Japan offers some sobering data about how long the coronavirus can stay viable on things like cell phones, touch screens, money or fabric. Hint: It’s not hours but days!
Do People Become Infected with COVID-19 by Breathing or Touching?
In the earliest days of the pandemic, the CDC and WHO suggested that you had to be pretty darn close to someone who was spewing droplets to catch the coronavirus. The magic number was 6 feet. If you were at least 6 feet away from someone who was sick, you were supposed to be safe, even if you were not wearing a mask.
More recently, though, the CDC has backtracked. These public health experts acknowledge that viable viral particles can float on air currents and remain aloft for hours. The CDC guidance of October 5, 2020 is titled “SARS-CoV-2 and Potential Airborne Transmission.”
Is Breathing the Problem?
The sad truth is that we do not have an army of public health workers interviewing people who become infected with COVID-19. As a result, we don’t have big data on how most people contract this disease.
The CDC still clings to the idea that:
“The principal mode by which people are infected with SARS-CoV-2 (the virus that causes COVID-19) is through exposure to respiratory droplets carrying infectious virus.
“Droplet transmission is infection spread through exposure to virus-containing respiratory droplets (i.e., larger and smaller droplets and particles) exhaled by an infectious person. Transmission is most likely to occur when someone is close to the infectious person, generally within about 6 feet.”
Can you Become Infected with COVID-19 by Touching?
The CDC also suggests that you can become infected with COVID-19 by “contact transmission”:
“Contact transmission is infection spread through direct contact with an infectious person (e.g., touching during a handshake) or with an article or surface that has become contaminated. The latter is sometimes referred to as ‘fomite transmission.’”
Despite the fact that the CDC recognizes “fomite transmission” as a way of becoming infected with COVID-19, it has relegated this process to the back burner. Touching something such as a contaminated doorknob, elevator button or keypad is not considered a likely means of transmission.
We wish there were big data to verify this supposition. We still do not know whether contact transmission is an important contributor to the spread of COVID-19.
How Long Does SARS-CoV-2 Stay Viable?
So-called experts have been arguing about viral viability for months. We wrote about fomites on March 31, 2020 in this article:
Can You Catch the Coronavirus From the Air or Surfaces?
There is disagreement about how you can catch the coronavirus. Some say you can’t catch COVID-19 from aerosols. The NEJM offers a different perspective.
In it we described research published in the New England Journal of Medicine (March 17, 2020).
The authors described “surface stability of SARS-CoV-2.”
We described their experiment this way:
“Can you catch the coronavirus by touching a gas pump, an elevator button, a doorknob or a stylus at the pharmacy counter? The researchers measured how long the coronavirus lasted on surfaces. They could retrieve viable virus from plastic and stainless steel for up to three days.”
Australian Research and Viable Virus on Surfaces:
Scientists from the Australian Centre for Disease Preparedness agree with their CDC colleagues that (Virology Journal, Oct. 7, 2020):
“The transmission of SARS-CoV-2 appears to be primarily via aerosols and recent studies have shown that SARS-CoV-2 is able to remain infectious in airborne particles for greater than 3 h.”
But they are quick to note that:
“The role of fomites in the current pandemic is yet to be fully determined, although they have been suggested as a potential mode of transmission…Broadly, viruses have been shown to be readily transferred between contaminated skin and a fomite surface, with high contact surfaces such as touchscreens on mobile phones, bank ATMs, airport check-in kiosks and supermarket self-serve kiosks all acting as fomites for the transmission of viruses. Fomite transmission has previously been shown to be a highly efficient procedure, with transmission efficiencies of 33% for both fomite to hand and fingertip to mouth transfer for bacteria and phages.”
The Aussies also point out that:
“Fomite transmission has been demonstrated as an important factor in the spread of other coronaviruses such as porcine epidemic diarrhea virus, as well as being suspected for Middle East Respiratory Syndrome coronavirus, human coronavirus 229E and OC43 and SARS-CoV-2.”
What They Did:
The researchers determined that the coronavirus can stay viable on a variety of surfaces for a surprisingly long time. They tested both paper and plastic money, stainless steel, glass and cotton cloth. The investigators also tested virus survival on vinyl, such as the film commonly used to protect mobile phone screens as well as grab handles on public transport.
They found that the virus could survive nearly a month on money, glass, vinyl and stainless steel at room temperature. They caution that touch screens on cell phones, ATMs, airport check-in kiosks and grocery store self-serve check-out stations could be contaminated. At 68 degrees Fahrenheit, the virus survived up to 14 days on cotton.
Can People Become Infected with COVID-19 by Touch?
The Australian team used a representative amount of virus in their experiments. They describe it as a “fluid matrix equivalent to that typically excreted by infected patients.” In other words, if someone coughs or sneezes into their hand and then touches something, they could easily transfer a lot of virus to that something.
They point out that:
“The persistence of virus on both paper and polymer currency is of particular significance, considering the frequency of circulation and the potential for transfer of viable virus both between individuals and geographic locations.”
“The persistence on glass is an important finding, given that touchscreen devices such as mobile phones, bank ATMs, supermarket self-serve checkouts and airport check-in kiosks are high touch surfaces which may not be regularly cleaned and therefore pose a transmission risk of SARS-CoV-2. It has been demonstrated that mobile phones can harbour pathogens responsible for nosocomial transmission, and unlike hands, are not regularly cleaned.”
This study reveals that the warmer the temperatures and the higher the humidity, the shorter the viability of the virus. While it survives on surfaces for four weeks at 68 degrees Fahrenheit, the SARS-CoV-2 virus could only persist for seven days at 86 degrees and for one day at 104 degrees.
That might partially explain why the virus retreats in the summer and roars back in the winter. This virus survives longer when humidity drops to around 50 percent, which happens when the heat comes on.
The Australian study is not the only research to suggest that SARS-CoV-2 can remain viable longer than most people realize. Japanese researchers have also investigated coronavirus survival (Clinical Infectious Diseases, online, Oct. 3, 2020).
They found that SARS-CoV-2 could persist up to 11 hours on human skin. That’s much longer than the influenza virus and might contribute to the high transmissibility of COVID-19.
The authors conclude:
“In conclusion, this study shows that SARS-CoV-2 may have a higher risk of contact transmission than IAV [influenza A virus] because the first is much more stable on human skin than the former [influenza A virus]. These findings support the hypothesis that proper hand hygiene is important for the prevention of the spread of SARS-CoV-2. Thus, this study may contribute to the development of better control strategies in the context of COVID-19 to prevent the occurrence of the second or third waves of this pandemic.”
Both studies reinforce the public health importance of hand washing for helping to control the spread of this disease. We would also suggest that disposable gloves may make sense when shopping or touching things that could be contaminated by other people who have been infected by COVID-19.
We need much better research to tell us exactly how people catch COVID-19. Whenever someone becomes sick, public health authorities should attempt to determine how that happened.
Most of the time, the people in charge shrug and move on. There may even be some contact tracing after the fact. But we would like to know more about super spreaders and how they 1) become infected with COVID-19 and 2) how they transmit the virus to others.
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