You have doubtless heard a lot of public health pronouncements over the last few weeks, repeated with great certainty. Stay six feet away from other people and you will be safe from the coronavirus. Don’t worry about wearing face masks. They aren’t helpful. But is there science to support such statements? You may be surprised to learn that research to corroborate such confidence is sorely lacking. It may be harder to prevent COVID-19 than public health authorities first imagined.
The University of Nebraska Scary Study!
Most of the country has gotten the message that maintaining physical distance between people is essential to slowing the spread of COVID-19. But just how much distance is needed to protect us from this infection?
New research from the University of Nebraska demonstrates that there is a wide range of viral shedding from patient to patient (MedRxiv, preprint, March 26, 2020). The investigators collected samples from isolation rooms and concluded that people shed virus when they breathe, go to the bathroom or handle things.
What the Scientists Did:
The researchers collected actual data from 13 patients with confirmed SARS-CoV-2 (the virus that causes COVID-19). They were being quarantined in the Nebraska Biocontainment Unit (NBU). The rooms were “negative pressure equipped.” That means the air inside the patient’s room was not supposed to escape.
Each room had its own bathroom. Health care workers wore PPE (personal protective equipment) and followed strict protocols to prevent COVID-19 from escaping the quarantine rooms.
The investigators took samples from “common room surfaces, personal items, and toilets.” They also tested ventilation grates, window ledges and medical equipment. Air samples were collected from the rooms themselves, the floors outside the rooms and from the hallways of the biocontainment unit.
Health care workers also wore personal air samplers while they were doing the testing. Patients stayed at least six feet away from the testers while they were sampling the air.
What the Scientists Found:
Over three-fourths of the personal items were positive for SARS-CoV-2 in the tests. Over 80% of the medical equipment, cell phones and computers tested positive. Ditto for the toilets and window ledges. Ventilation grates also tested positive.
We are especially concerned about the air sampling results. The researchers reported that in-room air samples produced positive results in over 60 percent of the cases. That’s not too surprising, although in one case the sampler was farther than six feet from the patient.
The real concern, however, was that the researchers found viral RNA in the air in hallways outside the rooms. These rooms had negative pressure of the sort that is recommended for optimal care of COVID-19 patients. Very few hospitals have significant numbers of rooms with negative pressure. Virus is not supposed to escape such rooms, but these results show that it can.
The scientists did not measure the size of the virus particles they detected. However, they observe that the data suggest that viral RNA was circulating in aerosol form. Not only did they find evidence of virus in the air outside the rooms, but in addition, the personal air samplers worn by the investigators were all positive even though the patients were neither coughing nor sneezing when the researchers were in the rooms.
Droplets vs. Aerosols:
If there is a bottom line to the significance of this research it boils down to droplets vs. aerosols. Many experts are confident that the primary transmission of COVID-19 is through droplets that sick people expel when they cough or sneeze. This research suggests the possibility of aerosol transmission.
Droplets are significantly larger than aerosolized particles and they don’t travel as far. That is why we have been urged to stand six feet apart. Droplets are not supposed to travel beyond that magic number. We have doubts about that. You will shortly read about a recent JAMA study demonstrating much farther spread.
Aerosols, however, are much smaller than droplets. When someone talks or just breathes they exhale particles in an aerosol mist that is impossible to see except under special circumstances.
The Conclusions:
The researchers at the University of Nebraska offer this conclusion:
“Taken together these results suggest that virus expelled from infected individuals, including from those who are only mildly ill, may be transported by aerosol processes in their local environment, potentially even in the absence of cough or aerosol generating procedures. Further, a recent study of SARS-CoV-2 in aerosol and deposited on surfaces, indicates infectious aerosol may persist for several hours and on surfaces for as long as 2 days.”
A letter sent to the White House on April 1, 2020 by a prestigious committee of the National Academy of Sciences reinforces this message. The gist of the message is that talking or breathing can spread viral particles in the air through an invisible aerosol cloud.
Some extracts from the letter:
“While the current [coronavirus] specific research is limited, the results of available studies are consistent with aerosolization of virus from normal breathing.”
“This letter responds to your question concerning the possibility that [coronavirus] could be spread by conversation, in addition to sneeze/cough-induced droplets. Currently available research supports the possibility that [coronavirus] could be spread via bioaerosols generated directly by patients’ exhalation.”
How Far Can Viruses Travel?
The Nebraska researchers refer to an “aerosol generating procedure.” That is a fancy way to describe a cough or a sneeze.
A study published in JAMA (March 26, 2020) suggests that a person sneezing emits a gas cloud that can extend up to seven or eight m (meters) (equivalent to 27 feet). What’s more, that violent puff contains clusters of droplets that don’t dry out or drop off nearly as rapidly as previously believed.
You really have to see what this looks like! Here is a link to the JAMA study along with a photo and a video that will make your hair stand on end. Here is the author’s conclusion:
“Given the turbulent puff cloud dynamic model, recommendations for separations of 3 to 6 feet (1-2 m) may underestimate the distance, timescale, and persistence over which the cloud and its pathogenic payload travel, thus generating an underappreciated potential exposure range for a health care worker. For these and other reasons, wearing of appropriate personal protection equipment is vitally important for health care workers caring for patients who may be infected, even if they are farther than 6 feet away from a patient.”
So, coughs and sneezes are bad! They spread viral particles far and wide. But just breathing and speaking can shed viral particles as well. Some scientists in China reported finding virus particles in hospital ventilation systems, again supporting the gas cloud hypothesis.
A Contradictory Perspective:
There are many public health experts who do not buy these data. They maintain that you can prevent COVID-19 by standing six feet away from other people. And they insist that viral particles are not necessarily contagious. These authorities note that just because you can detect viral RNA in the air or on a surface does not mean it is dangerous.
Many of these skeptics have criticized a study published in The New England Journal of Medicine (March 17, 2020). The authors reported that SARS-CoV-2 remained viable in the air for at least three hours. They also suggested that the virus could last for up to three days on stainless steel or plastic.
The optimists refuted the implications of this research by saying that viral particles might not be contagious. They also complained that the experiment did not reflect real world conditions. We would suggest that the University of Nebraska study represents real world conditions and supports the findings in the NEJM.
The People’s Pharmacy Perspective:
Here is an article that we wrote about the Diamond Princess contamination and the New England Journal of Medicine data:
Beware Surface Spread of Coronavirus Over Two Weeks!
How long can SARS-CoV-2 survive on door knobs? Surface spread of coronavirus might last over two weeks. RNA from the virus was found after 17 days on a ship
Trying to Prevent COVID-19:
The reason we have gone into such detail about the University of Nebraska research is to try to help you prevent COVID-19 infection. We believe that taking extra precautions is really important, even if we can’t prove they are absolutely necessary.
If we are wrong, it will be inconvenient. No one wants to stand 10 to 20 feet away from others. But if we are right, we may have helped you prevent a COVID-19 infection.
The latest data underscore the importance of protective equipment for healthcare workers, even if they are farther from the patient than six feet. We only wish the heroes on the front line of this infection had more adequate gear.
Will Face Masks Help Prevent COVID-19 From Spreading?
If you think the six-foot physical distancing guidelines are now controversial, wait till you read about face masks. For several weeks we have been told by influential public health authorities that face masks will not prevent COVID-19 transmission.
The Surgeon General actively discourages the use of face masks. That may be changing. There are reports that some people at the CDC may be revising their opinions. We would not be surprised if there is a U-turn in the coming days.
Finding effective face masks online or at your pharmacy are a challenge. Until they are back in stock, we provide you some recommendations about do-it-yourself face masks. Here is a link:
Should You Be Wearing a Face Mask? Why Not?
Public health officials have told us wearing face masks are unnecessary. Were they wrong? Could wearing a face mask help you prevent COVID-19?
What Do You Think?
Share your thoughts about droplets vs. aerosols. What distance are you currently maintaining from others who don’t live with you? Is 6 feet enough or do you seek to be farther away? How do you try to protect yourself in elevators or public bathrooms? What about workers in supermarkets or pharmacies? How can they prevent COVID-19 exposure?
We would like to read your perspective on face masks in the comment section below.
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