Coronavirus Technology Solutions
October 7, 2020

Efficient Tight Fitting Masks are Needed to Beat COVID

Supreme Court Nomination Celebration was a Super Spreader Event

Increase the Effectiveness of Standard Face Masks

Ten to Forty Percent of Particles will Penetrate a Surgical Mask Due to Poor Fit


Respirators are Much More Protective than Surgical Masks

Reinfection is Happening but not on a Large Scale

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Efficient Tight Fitting Masks are Needed to Beat COVID

The evidence appearing in the daily alerts in the Coronavirus Technology Solutions shows that

·         Most of the transmission is through small aerosols

·         Large droplets on the mask’s internal surface become small aerosols

·         The typical surgical mask is only half as efficient as a tight fitting high efficiency mask

Small aerosols containing coronavirus are inhaled and exhaled through the periphery of surgical masks. The COVID battle will be won with either N95 masks or improved versions of surgical masks which minimize leakage.

Tight fitting masks are inherently more uncomfortable and require more effort to wear properly than the typical surgical mask. Since the virus travels as easily as perfume or cigarette smoke the tighter the fit the better. There are recent innovations to provide a tighter fit. One is a self-adhesive mask.  Others add a peripheral band which is adjustable. This is a solvable problem which will not add much to cost.

An individual should have multiple mask types which he wears as conditions warrant.  This can range from N100 down to tight fitting surgical masks.  It can include non-valved as well as valved designs.

Much of the time no mask will be required. The mask selection at any point in time should be appropriate to the risk in a specific environment. This risk is indicated by

• New COVID-19 case counts
• Incidence rate (new cases per 100,000 people), and
• New case trajectory (whether the number of new cases is going up, going down, or staying the same over time).
• Indoor and outdoor pollution levels
• Testing Positivity ratios
• Site specific factors such as number of people per ft2. Air changes per hour and efficiency of HVAC systems

Individuals should continually assess risks and wear the appropriate mask for the circumstances.  Let’s take an example which  is prominent in the news The cost of holding the Supreme Court nomination at the White House in September is estimated at $140 million as a result of  coronavirus cases and deaths which will result from this one event.

This amount is based on the eventual deaths of two people and infection of 100 people as attendees pass the virus along to non-attendees. Social distancing would have cut the cases to 50. In addition surgical masks would have reduced the cases by another 25. N95 masks would likely have reduced the cases to five.  Even with the N95 masks the risk is unacceptable. When all costs including quality of life are considered it would have been an $8 million cost for one event. This is much less than the $140 million actually generated with no masks or social distancing but still too high a price to pay.

This event was predictably high risk. One metric would be to assume a net positive ratio in excess of 15 as a rating of risk for this event. There are some parts of the country where the risk is well less than 1%  if only a small number of local people attend.

The number of cases of an infection for a proposed event can be predicted depending on the risk.  In this case we used net positive rate as the indicator and compared results for rates of 1 to 15.

McIlvaine has created a methodology to assess the costs and benefits of various mask decisions.  This includes healthcare costs, economic costs and life quality costs. It is then balanced by the benefits of lives saved and cases avoided which has both economic and life quality components.  There is a detailed analysis of these costs and benefits for the White House event in  the October 7 Coronavirus Technology Solutions alert.

The costs and benefits of various masks along with their availability are analyzed in the High Efficiency Mask Market and Supplier Program.

Click here to view a video description or Click here for the power point display

Supreme Court Nomination Celebration was a Super Spreader Event

The Supreme Court Nomination is turning out to be a super spreader event. This event can be used as an example of how best to fight the disease. The event was held partially indoors and partially in the Rose Garden with closely placed chairs.

There were therefore the following potential factors in the extent of the transmission

1.      Number of infected people in attendance

2.      Indoor air filtration efficiency and flow

3.      Outside air wind velocity and direction

4.      Number of people wearing masks

5.      Types of masks worn

6.      Activities of participants

The benefits have to be weighed against the costs which include both  economic and social. The most extreme form of social distancing is quarantining with high life quality costs. If the  Supreme Court nomination ceremony had been remote, the transmission risk would have been eliminated. At a minimum keeping a distance of six feet would be a social distancing tool.

In terms of the social cost of a virtual ceremony the nominee could very easily traded a month or oven months of vacation time for the one Rose Garden event. Most of the attendees would probably been willing to give up one day of vacation for the event.

The life quality cost of staying six feet apart at the ceremony might have been worth trading a few days of vacation by the nominee but probably not worth a few hours on a Hawaiian beach for most attendees.

At this point at least ten people probably contacted the virus directly at the event. The fact that each of them is statistically likely to have infected 20 other people who in turn will infect 40 people means that the number of cases and ultimately deaths attributable to the event will be substantial. Let’s assume that there will be two deaths and 100 infections as a result of the event.  At $20 million per death and $1 million per infection, the economic and life quality costs will exceed $140 million just from this one event.

Social distancing, HVAC with efficient air filters, and masks would have been useful in minimizing the transmission.

Social distancing: the protocol to keep six foot distant at all times by itself may have cut the transmission in half.  No capital cost would have been required. So  $70 million would have been saved.

But the cost would still be $70 million. Fifty people would become infected and one would die.   The virus floats through the air like perfume.  So the air flow and speed both inside and outside would be a factor.

HVAC:  portable room air purifiers could have been provided for every 100 ft2 area outside. fifty air purifiers would have a capital cost of around $25,000 but the rental for one day might be only $2,000.  The HVAC in the inside air could have been upgraded to more than 15 air changes per hour and HEPA filters. The cost for a large room might be $40,000 but if it is used continually the cost could be depreciated over a number of events. Alternatively the portable air filters could have been moved inside for that part of the event. So the cost for this event might be  $4,000. The savings could be 15 cases and 0.25 deaths or $20 million.  

Surgical masks:  the effectiveness will only be 50% due to leaks around the masks. So the additional saving after social distancing would be 25 cases and 0.5 lives for a saving of  $35 million. The cost for 200 people wearing a surgical mask during the event would be $400. Using the vacation time as an example of social cost the nominee may have been willing to trade a week’s vacation time for the  event to be free of masks. Most attendees would be unlikely to trade even a few hours.

N95 Masks:  the effectiveness will be 90%. It would eliminate 45 cases  and 0.9 lives lost.  So the saving is $63 million. The cost would be $800.  The social cost of the N95 might be a little higher than for the surgical mask but not if the N95 is designed for comfort.

Increase the Effectiveness of Standard Face Masks

Reducing mask leakage will very important. There is progress being made. One innovation came after a study by two University of Wisconsin-Madison mechanical engineering professors revealed that various existing masks and face shields allow tiny particles to escape, both through the material and at the edges. If the wearer is infected with the novel coronavirus, that means the virus could travel from the wearer’s mouth or nose and infect those around them.

The research came from professors Scott Sanders and David Rothamer, who usually study combustion engines and use laser illumination to find the leaks. Back in April, they turned their expertise and tools toward solutions to the growing pandemic. 

Over the following months, they conducted numerous tests of various face coverings, placing the coverings on mannequins and using a foggy-looking substance made from salt and air to simulate the aerosolized particles in human breath.

In one experiment, they set 17 former CPR mannequins in a classroom to simulate students wearing various forms of protective equipment and pumped the aerosols through them. In another experiment, they pumped a larger volume of aerosols through a single mannequin’s mouth and recorded video of the results. 

The video of the mannequin wearing the face shield shows fog escaping out the bottom, while the mannequin wearing a loose-fitting surgical face mask fogged from the top and sides. 

For a better seal, the two researchers used packing tape to attach the masks to the mannequins’ heads, and the amount of leaking aerosols fell dramatically. 

Knowing that living humans wouldn’t tape their masks to their faces, they asked Lennon Rodgers, director of UW-Madison’s Grainger Engineering Design Innovation Lab, to help devise an alternative for tightening the fit of a standard surgical mask.

Rodgers and Sanders soon discovered online that there were a few products already on the market for this purpose, known as “mask fitters,” but none met the goals for the product, Rodgers said, noting the relative expense of 3D printing.

“I was thinking this has to be dead simple. It has to be so cheap,” he said, citing the success of the original Badger Shield design which used only three easy-to-find materials and was soon being produced at a massive scale by manufacturers around the world. 

“My thought was like if we wanted to make tons and tons of these, like millions, and make it very cheap, 3D printing is pretty much out the window.

”

The Badger Seal, the latest PPE innovation released by the UW Makerspace, can be worn over a surgical or cloth mask to provide a tighter fit and reduce particle penetration. The design was dubbed the Badger Seal. When Sanders and Rothamer tested the Badger Seal on the mannequins, they now needed lasers to detect the escaping aerosols that had previously been visible to the naked eye. The device increased the filtration efficiency of a standard surgical mask by three times and increased the efficiency of a cloth mask by four to eight times. Those efficiency gains led to even bigger changes in particle penetration. When worn over a three-layer disposable mask, the Badger Seal yielded particle penetration 15 to 18 times less than that of a cloth mask.

Like the team’s other personal protective equipment designs, the Badger Seal designs are open-source, which means there's no patent. People can build their own using instructions and videos.

Each can be made in about five minutes with basic tools and materials that cost less than a dollar, and members of the UW-Madison campus community can make their own using materials at the DIY station in the Makerspace lobby.

The university has already built about 2,500 Badger Seals in-house. Some have been distributed to faculty and custodians, but plenty are still on hand, Rodgers said.

The research side of the project is likely complete. “It's more now about kind of getting the word out there about the various PPE options people have that they probably don't know about,” Sanders said, though he’s still running tests weekly.

Digital Publishing and Printing Services, the university’s printing service, which pivoted back in April to make Badger Shields for UW Health, is now making Badger Seals for campus. If demand outside campus proves sufficient, Rodgers said he and his team would find a manufacturer interested in producing them. But so far, the new design hasn’t seen the same interest as the Badger Shield and it’s extra-protective cousin the Badger Shield Plus, the latter of which launched as teachers and students (both K-12 and college) prepared for a return to in-person instruction

https://madison.com/ct/news/local/uws-badger-seal-promises-to-make-masks-work-better/article_9b61800b-3f7f-5a0d-ab19-d6930029155b.html

Ten to Forty Percent of Particles will Penetrate a Surgical Mask Due to Poor Fit

The filters of most surgical masks will allow a large majority of wearer-generated particles to penetrate and will collect only a small percentage of airborne particles generated by infectious patients. Even when equipped with filters demonstrating relatively high collection efficiency, 10% to 40% of particles will penetrate the face seal as a result of poor fit. For aerosols containing organisms with a low infectious dose (e.g. tuberculosis), this level of face seal leakage would not prevent a potentially infectious exposure during even a brief encounter with a patient generating copious amounts of aerosol. The poor performance of dental masks is of particular concern, given dental surgeons' close proximity to patients and the high aerosol concentrations generated by dental procedures.

Respirators are Much More Protective than Surgical Masks

There are few studies that compare the clinical efficacy of respirators versus surgical masks. In one Toronto hospital, all attending health care workers reported to be wearing “respirators” contracted severe acute respiratory syndrome (SARS) during a patient intubation. Closer examination reveals that employees were wearing surgical masks, not respirators. Another study found that nurses in a Toronto hospital not consistently wearing either a filtering face-piece N95 respirator or a surgical mask had four times the risk of contracting SARS as those consistently wearing respirators or surgical masks. Fit testing is not required and was infrequently employed in Canada during the SARS outbreaks.

Data illustrate how important fit is to preventing inward leakage of particles. Qualitative fit tests are considered valid measures of personal protection for respirators that must achieve a fit factor of 100 (used in atmospheres less than 10 times the permissible exposure limit). Although two subjects were able to pass the qualitative fit test on two different surgical masks when assisted with fit, the authors believe these results occurred because of temporary taste desensitization. Quantitative fit test results support this conclusion. None of the test surgical masks attained an individual fit factor of 100, the minimum level expected for a half-mask filtering face-piece respirator. Assistance with fit made no difference in the degree of fit.

Qualitative fit test results also illustrate the importance of surgical mask design. Mask D showed the second highest filter efficiency but the lowest fit factor. One of the reasons for poor fit may be the ear loop design, which limits adjustability of fit. To be effective in reducing wearer's exposure to airborne substances, a respiratory protection device needs to have sufficient fit as well as high filtration efficiency

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7115281/

Reinfection is Happening but not on a Large Scale

On 15 August, a 33-year-old man landed in Hong Kong after flying home from Spain. On arrival, he was screened for coronavirus. Despite feeling well he tested positive. It was the second time he had picked up Covid-19 in less than five months.

The case immediately caught scientists’ attention. The man was the first in the world to have a confirmed coronavirus reinfection and there were positives to take from the report. First and foremost, he was asymptomatic. Although reinfected with Sars-Cov-2, his immune system swung into action fast and contained the virus without him knowing.

Many researchers took heart from the case, but since the patient came to light a flurry of reinfections around the world have raised fresh concerns. Within days of the Hong Kong case being made public, doctors in the US reported that a 25-year-old man from Reno, Nevada, had been hospitalized with a Covid-19 reinfection after shrugging off an earlier brush with the disease. More cases soon followed. While most infections were no worse the second time around, a good number cropped up – in the US, the Netherlands, Ecuador and India – where the reinfection was more severe.

“It’s really hard to find a pattern right now,” said Akiko Iwasaki, a professor of immunobiology at Yale University who has been following cases of reinfection closely. “Essentially every case is different.”

So far, only two dozen or so reinfections have been confirmed worldwide in a pandemic that has infected more than 30 million people. For now at least, reinfection seems uncommon. But scientists point out that confirming reinfection is no easy task and many cases are missed.

To confirm a reinfection, scientists must examine the genetic code of the virus from each round of illness and prove they are distinct. That means having access to both sets of swabs and the wherewithal to do whole genome sequencing. Even in hospitals where the capacity exists, such tests are rarely done. Reinfected patients simply go unnoticed or unreported. “There is probably a lot more than we are seeing,” said Iwasaki.