The miracle of mucus

Remember when it was nearly impossible to buy disinfectant wipes? In the early days of the COVID-19 pandemic, people desperately wiped down surfaces to prevent the spread because initial studies showed the virus could live on certain surfaces for weeks.

But later in 2020, newer studies showed touching a contaminated surface was not the real reason the infection was spreading. Most people were getting sick from virus-laden nasal droplets transmitted in the air.

Now, new research from University of Utah biomedical engineering assistant professor Jessica Kramer explains why the coronavirus is not really transmitted by touching surfaces. And it all has to do with our mucus, the slimy gunk that comes from our noses.

Kramer’s research was published in the newest issue of ACS Central Science. You can read a copy of it here.

Human mucus and saliva, when dry on a surface, may actually prevent the spread of coronaviruses, Kramer has learned. People produce different forms of mucus and salivary proteins, called mucins, depending on their unique genetics, diet, and environment. And certain forms of mucins form a barrier around the live virus which prevents the spread of infection.

In a laboratory, the research team tested two transmission modes: direct contact, such as touching, kissing, or a nearby sneeze, and infection from touching a contaminated surface. Researchers learned that without mucins to act as a barrier, the virus was able to spread well from surfaces or direct contact. But with the mucins in mucus and saliva, the rate of infection drops significantly when the mucus and the virus dry on the surface. That could happen in as little as just a few minutes, she says.

That’s because mucins are a special class of proteins that have sugars attached to them. The virus itself binds to the sugars instead of attaching to the surface of a human cell to replicate. The mucins act as a decoy to bind and trap the virus before it gets to the cells underneath.

Kramer’s team confirmed that without mucins, the coronavirus was viable and infected cells after recovery from a variety of common touch surfaces, including plastic, glass, steel, and surgical masks. Virus samples were infectious even after sitting dry on plastic for several days. However, when scientists recovered virus dried in simulated sneeze droplets with mucins, infection was essentially eliminated. This was true whether the virus had been dry for five minutes or three days.

Prior lab studies throughout the pandemic reported that coronaviruses are viable on surfaces for days or even weeks. However, these studies examined virus in water or a buffer rather than salivary fluid.

“This research explains how the mucins work, which we think is important,” Kramer says. “If we understand how they block the virus from infection, we can develop drugs that mimic that action.”

This new knowledge could help lead to new drugs that might be used by healthcare workers and first responders in high-risk environments. These drugs could for a short time prevent the virus from getting into their cells, as opposed to a vaccine that fights off the infection once it’s already in the cells.

Report provides evidence that lab leak theory unlikely

Today’s COVID-19 pandemic likely began when an infected animal passed the SARS-CoV-2 virus to a human at a live animal market in Wuhan, China. In a critical review published in the peer-reviewed journal Cell,21 scientific experts from across the world present evidence that this scenario is much more probable than the novel disease originating from a laboratory accident, a theory that has received attention in the media.

“The discussion over the origins of the pandemic have become politicized and heated, and we felt the time was right to take a critical look at all of the available evidence,” says Stephen Goldstein, PhD, an author on the paper and evolutionary virologist at University of Utah Health. Corresponding authors are Edward Holmes, PhD, The University of Sydney, Australia, and Andrew Rambaut, University of Edinburgh, UK. “Preventing future pandemics requires the political will to cut off the routes by which these viruses enter the human population. Focusing in the wrong direction will preclude those efforts from occurring.”

The experts laid out the evidence. Learn more in an interview with Goldstein.

Animal markets are an epicenter for early COVID-19 cases

Maps showing the first documented cases of COVID-19 in Wuhan, China. Originally published in Cell, adapted with permission.

Maps pinpointing geographic locations of the first wave of COVID-19 cases in December 2019, show they initially emerged close to the site of the Huanan Seafood Wholesale Market in Wuhan, China, as well as other markets reported to have live animal trading. In the weeks following, cases radiated outward geographically. Those cases were followed by excessive deaths in January 2020, a second marker of how the virus spread through the population. Similarly, those deaths were initially localized to near the animal markets.

“It tells us where the epidemic began and where intense transmission began,” Goldstein explains. “This suggests that the epidemic began in markets in this district: the Huanan market and possibly other markets as well.”

Lack of evidence for laboratory leak

The Wuhan Institute of Virology, often cited as the source of a lab leak, is also marked on the map, but is a distance away from the live animal markets. None of the very first documented cases—or excessive deaths within the first week of emerging—were located near the institute. None of the first documented cases were reported as being related to staff at the laboratory. There is no evidence that researchers at the institute worked with SARS-CoV-2 nor a closely related virus.

Human infectious disease frequently originates in animals

COVID-19 isn’t the first coronavirus-based infectious disease associated with animal markets. The 2002 and 2003 outbreaks of SARS, the disease caused by the SARS-CoV virus, were associated with markets in China that sold live animals. In addition to SARS-CoV and SARS-CoV-2, five other coronaviruses have crossed into humans from animals in the past 20 years. Combined with the observation that the majority of viruses in humans, both coronaviruses and other virus types, came from infected animals, it would not be unexpected for SARS-CoV-2 to have entered the human population in the same way, the authors say.

“Preventing future pandemics requires the political will to cut off the routes by which these viruses enter the human population. Focusing in the wrong direction will preclude those efforts from occurring.”

No signs of man-made changes to the virus

A recurring argument for the lab leak theory is that the virus, SARS-CoV-2, carries a specific short genetic code that is sometimes engineered into laboratory products, called a furin cleavage site. To investigate, researchers have previously analyzed genetic sequences from multiple coronaviruses and found the code in question to be commonplace among them. The authors of this review further determined that the specific code in SARS-CoV-2 is imperfect and therefore would not perform its function well.

“There is no logical reason why an engineered virus would utilize such a suboptimal furin cleavage site, which would entail such an unusual and needlessly complex feat of genetic engineering,” the authors write. Examination of the virus’ sequence has not turned up other potential signs of deliberate manipulation.

While a substantial body of scientific evidence supports SARS-CoV-2 originating from wildlife, those animals have not been found. “We can’t rule out the possibility of a lab accident,” Goldstein says. “It can’t be dismissed entirely, but it is highly unlikely. There’s no evidence for it right now.”

U designs innovative respirator system

In response to the overwhelming demand for Personal Protective Equipment (PPE) due to COVID-19, the Center for Medical Innovation (CMI) at University of Utah Health has designed an enclosed Powered Air Purifying Respirator (PAPR) system to provide health care workers safe and reusable PPE when working with COVID-19 patients.


Designed to fully enclose the face of the user, a PAPR system consists of a hood or helmet and a filtered respirator to provide those wearing the system a constant flow of clean air. This positive pressure prevents entry of unfiltered air and protects the health worker from inhaling aerosolized COVID-19 particles.

However, due to the specialized nature of the equipment, hospitals typically have a limited quantity of the systems on-hand at any given time.

“PAPR systems provide excellent protection and can drastically reduce the consumption of single-use PPE, such as common N95 respirators,” explains Bryan McRae, interim co-director at CMI. “Unfortunately, PAPRs have now been unavailable for standard suppliers for more than a month. The CMI team and our University of Utah Health colleagues have been nimble and innovative in developing a solution to bridge the gap while traditional PPE sources remain uncertain.”

By combining readily available components such as mobile battery packs, portable fans and replaceable medical grade filters with several 3-D printed adapters, the assembled PAPR system designed by CMI expands the options to protect health workers treating COVID-19 patients.

The PAPR system on a table. The components are a plastic face shield surrounded by a white material that looks like a shower cap, connected to a long tube that plugs into a portable air filtration system.

The PAPR system is made by combining readily available components such as mobile battery packs, portable fans, and replaceable medical grade filters with several 3D printed adapters.

Using a standardized rating system known as “Fit Factor,” PAPR systems typically rate somewhere between 200 and 1000 on the quantitative fit testing scale. This means the system reduces the concentration of 0.3 micron aerosolized particles inside the system by 200 to 1000 times when compared to the air outside the hood. The PAPR system developed by the CMI was assessed by the Rocky Mountain Center for Occupational and Environmental Health at the University of Utah and offers a Fit Factor of 400 or better.

For comparison, on the OSHA scale known as an Assigned Protection Factor (APF), this PAPR offers an APF between 25 and 400, providing superior protection when compared to the common N95 respirator masks which typically only provide an APF of 10.

As the University of Utah Hospital braces for a potential surge of COVID-19 patients, all options to expand the supply of PPE are being explored. This includes retrofitting older pieces of still-viable equipment to the newer PAPR systems. Because of the customized 3-D printed adapter used to connect the respirator to the helmet, CMI’s PAPR system can also connect to older models of PAPR helmets still in-stock, enabling hundreds of previously unusable helmets to be worn safely and comfortably by health care workers at University Hospital.

Integrating feedback directly from those on the frontlines of COVID-19 management into the final PAPR system design, production has already begun to manufacture several hundred units as quickly as possible. Utilizing 3-D printing equipment on campus, including over 30 printers in production at the Marriott Library, Eccles Health Sciences Library and the College of Engineering, many of the PAPR systems will be ready for implementation within the week. Additional manufacturing support is being generously provided by O.C. Tanner and L3 Technologies.

“We are especially grateful for the expertise and insight from our university and industry partners,” said Bernhard Fassl, interim co-director of CMI. “As we further develop solutions for health workers during the COVID-19 outbreak, we will continue to rely on our community partners to help us implement these projects.”

Later this week, CMI will be releasing design specifications for the PAPR system to other health care groups and the public. This includes Indian Health Services and the Navajo Nation, as well as CMI’s global health partners in India, Kenya and Nepal, to provide guidance on assembly and use in resource-limited settings.

For more information about the PAPR system and the Center for Medical Innovation’s response to the COVID-19 outbreak, please click here.

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Utah’s spring air quality better than usual during pandemic

As stay-at-home measures went into place in March 2020, many wondered how fewer cars on the road would impact Salt Lake’s air quality. The first preliminary measurements are now in. Air quality along the Wasatch Front in March is usually good, but the reduction in emissions from COVID-19 stay-at-home measures have made air quality even better than usual.

The results here are some of the first to integrate ground-based air quality and greenhouse gas emissions with satellite observations to understand how emissions have changed .

“These measurements, taken together, paint a consistent picture of cleaner air from reduced emissions, especially from reduced traffic,” said Logan Mitchell, research assistant professor in the Department of Atmospheric Sciences at the University of Utah, who conducted the analysis using data from Utah Department of Environmental Quality (DEQ) monitoring stations. “It shows how fast the air quality improves after a reduction in emissions and suggests that as the economy starts to recover and emissions ramp up, we’re going to see our air quality get worse again.”

“For environmental scientists, this was a once-in-a-lifetime opportunity to study the air quality impacts of fewer cars on the road,” said Bryce Bird, director of the Utah DEQ’s Division of Air Quality. “We are looking forward to further analyzing the data our monitors collected during this period when residents were teleworking and driving less. Dr. Mitchell’s initial analysis shows a lot of promise and hopefully, the final results will help inform behavior and policy in the coming years.”

March air quality by the numbers

Measurements of all air pollutants come from a monitoring station at Hawthorne Elementary in Salt Lake City and additional measurements of carbon dioxide come from monitoring stations in Sugarhouse, at the U, and in the southwest Salt Lake Valley. The measurement period reported here is the last half of March since many of Utah’s stay-at-home measures were in effect by March 15.

  • NOx (oxides of nitrogen) levels were lower due to traffic reductions, especially during rush hour peaks. Nitric oxide (NO) levels were 57% lower than the average March, and nitrogen dioxide (NO2) was 36% lower than average.
  • O3 (ozone) is about the same as usual at midday but slightly elevated at night.  This is characteristic evidence of less NOxin the air and less reaction between NOx and ozone at night. It’s consistent with what scientists think urban air would look like with decreased NOemissions.
  • PM2.5 (particulate matter) is down by 41%, particularly at night. It’s not clear yet whether that’s due to reduced overall particulate matter emissions or reduced formation of particulate matter through atmospheric chemistry.
  • CO2 (carbon dioxide) levels are at 19% and 33% lower than average at the Sugarhouse and U stations, respectively.
  • SO2 (sulfur dioxide) is around typical levels. Mitchell says this isn’t surprising, as there aren’t many SO2 sources in the Salt Lake valley.

PHOTO CREDIT: Logan Mitchell

Pollutant concentrations by hour of day observed at the Utah DAQ Hawthorne site.

More analyses are forthcoming, and the data have not yet been peer-reviewed, Mitchell says. Also, analyzing the weather conditions from March 2020 will provide a more complete picture of how emissions compare to previous years.

“These results give me a lot of optimism about the future,” Mitchell said. “It shows that as we recover from the pandemic if we invest in clean energy and electric vehicles, it’s really possible to clean up the air.”

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Read the full report of preliminary results, including images, here.

Find current air quality conditions from the Utah DEQ here and measurements from stationary and mobile air quality monitors through the University of Utah here.