A simple, low-cost technique shows visual proof that face masks are effective in reducing droplet emissions during normal wear.

Eric Westman was one of the first champions of masking as a means to curtail the spread of coronavirus, working with a local non-profit to provide free masks to at-risk and under-served populations in the greater Durham, NC community.

But Westman, a physician at Duke University, needed to know whether the virus-blocking claims mask suppliers made were true, to assure he wasn’t providing ineffective masks that spread viruses along with false security. So he turned to colleagues in the physics department: Could someone test various masks for him?

“We confirmed that when people speak, small droplets get expelled, so disease can be spread by talking, without coughing or sneezing.”

Martin Fischer, a chemist and physicist, stepped up. As director of the Advanced Light Imaging and Spectroscopy facility, he normally focuses on exploring new optical contrast mechanisms for molecular imaging, but for this task, he MacGyvered a relatively inexpensive apparatus from common lab materials that can easily be purchased online. The setup consisted of a box, a laser, a lens, and a cell phone camera.

“We confirmed that when people speak, small droplets get expelled, so disease can be spread by talking, without coughing or sneezing,” Fischer says. “We could also see that some face coverings performed much better than others in blocking expelled particles.”

Notably, the researchers report, the best face coverings were N95 masks without valves—the hospital-grade coverings that are used by front-line health care workers. Surgical or polypropylene masks also performed well.

“If everyone wore a mask, we could stop up to 99% of these droplets before they reach someone else.”

But hand-made cotton face coverings provided good coverage, eliminating a substantial amount of the spray from normal speech.

On the other hand, bandanas and neck fleeces such as balaclavas didn’t block the droplets much at all.

“This was just a demonstration—more work is required to investigate variations in masks, speakers, and how people wear them—but it demonstrates that this sort of test could easily be conducted by businesses and others that are providing masks to their employees or patrons,” Fischer says.

“Wearing a mask is a simple and easy way to reduce the spread of COVID-19,” Westman says. “About half of infections are from people who don’t show symptoms, and often don’t know they’re infected. They can unknowingly spread the virus when the cough, sneeze and just talk.

“If everyone wore a mask, we could stop up to 99% of these droplets before they reach someone else,” Westman says. “In the absence of a vaccine or antiviral medicine, it’s the one proven way to protect others as well as yourself.”

Westman and Fischer says it’s important that businesses supplying masks to the public and employees have good information about the products they’re providing to assure the best protection possible.

“We wanted to develop a simple, low-cost method that we could share with others in the community to encourage the testing of materials, masks prototypes, and fittings,” Fischer says. “The parts for the test apparatus are accessible and easy to assemble, and we’ve shown that they can provide helpful information about the effectiveness of masking.”

Westman says he put the information immediately to use: “We were trying to make a decision on what type of face covering to purchase in volume, and little information was available on these new materials that were being used.”

The masks that he was about to purchase for the “Cover Durham” initiative?

“They were no good,” Westman says. “The notion that ‘anything is better than nothing’ didn’t hold true.”

The proof-of-concept study appears in the journal Science Advances.

Source: Duke University

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Social distancing and wearing a mask prevent you from spreading COVID-19, but they also protect you from getting it, two experts explain in a new video discussion of coronavirus transmission.

A range of new research on face coverings shows that the risk of infection to the wearer decreases by 65%, says Dean Blumberg, chief of pediatric infectious diseases at the University of California, Davis Children’s Hospital.

“People who say, ‘I don’t believe masks work,’ are ignoring scientific evidence. It’s not a belief system. It’s like saying, ‘I don’t believe in gravity.’

“On the issue of masks, I’d like to restart—because we’ve learned a lot,” Blumberg says. “We’ve learned more due to research and additional scientific evidence. What we know now is that masks work and are very important.”

Blumberg and William Ristenpart, a professor of chemical engineering, appeared on a recent livestream devoted to explaining how the coronavirus spreads and how to prevent transmission.

In their comments and answers to questions from viewers, Blumberg and Ristenpart repeatedly made the point that research continues to support the fundamental methods to prevent spreading COVID-19: Wear masks, maintain social distance, and keep social interactions outdoors whenever possible.

How masks work to stop COVID-19’s spread

There are two primary methods of coronavirus transmission, Blumberg and Ristenpart explain.

The first is via droplets a carrier expels, which are about one-third the size of a human hair but still large enough that we can see them. Masks create an effective barrier against droplets.

“Everyone should wear a mask,” Blumberg says. “People who say, ‘I don’t believe masks work,’ are ignoring scientific evidence. It’s not a belief system. It’s like saying, ‘I don’t believe in gravity.’

“You’re being an irresponsible member of the community if you’re not wearing a mask. It’s like double-dipping in the guacamole. You’re not being nice to others.”

“People who don’t wear a mask increase the risk of transmission to everyone, not just the people they come into contact with. It’s all the people those people will have contact with. You’re being an irresponsible member of the community if you’re not wearing a mask. It’s like double-dipping in the guacamole. You’re not being nice to others.”

The second major coronavirus transmission method is via the aerosol particles we expel when we talk. Those are about 1/100th the size of a human hair and are more difficult to defend against. Social distancing and staying outdoors, where there is more air flow, are helpful, Blumberg and Ristenpart say.

“Studies in laboratory conditions now show the virus stays alive in aerosol form with a half-life on the scale of hours. It persists in the air,” Ristenpart says. “That’s why you want to be outdoors for any social situations if possible. The good air flow will disperse the virus. If you are indoors, think about opening the windows. You want as much fresh air as possible.”

This is why, he says, places like bars are particularly hazardous for aerosols, on top of the likelihood of minimal distancing. “The louder you speak, the more expiatory aerosols you put out,” he says.

Other coronavirus transmission pointers

Plexiglass and cubicles as protection? The plexiglass shields in stores and restaurants only help somewhat. The same is true for office cubicles. But after a lengthy time, transmission is possible from aerosols if the air flow is not good, Blumberg and Ristenpart say.

“The way to think about that is to think about smells,” Ristenpart says. “If the person on the other side of a cubicle or plexiglass is wearing perfume, eventually, you’ll smell it. The aerosol particles are small enough to travel on air much like aromas. That’s why air flow is so important, along with other actions like wearing masks and social distancing.”

“We do know social distancing reduces the risk of transmitting the virus by 90%, and wearing masks decreases the risk by 65%.

Time of exposure matters: “If you’re going past someone very quickly in a grocery store,” Blumberg says, “the risk of getting infected is very low. It’s really lingering and talking that does it.”

Ristenpart adds: “It’s really important to know that just because you’re standing 6 feet or 7 feet away, if you have a prolonged conversation, there is still a risk. These aerosols can be carried along on weak air currents.”

Surface contact is less of a threat: There is no precise research on the prevalence of transmission from hand contact.

“For ethical reasons, we can’t contaminate a bunch of people’s hands, then have them touch their faces or other people’s faces,” Ristenpart says. “But backtracking infections and following transmission events shows surfaces or hand contacts are not a primary method.”

Which brings researchers back to droplets and aerosol particles as the primary methods of transmission.

“We know from other coronaviruses that this is primarily a respiratory transmitted illness,” Blumberg says. “There is a very small chance of transmission via groceries or mail or things like that. But washing hands is still always good.”

Children and COVID-19: Children are less likely—by half—to be infected if they are exposed, less likely to be symptomatic, and less likely to have a severe case if they do get sick, Blumberg says.

“They appear to be less likely to infect others,” he says. “This is different from other infections like the flu when they are carriers. This appears to be much more of an adult disease. But children can still get sick and can still transmit it to others, so it’s important to be as hygienical with them as their development allows.”

Masks and social distancing are key

Both scientists say the evidence has become even more powerful for wearing masks and social distancing. For instance, research shows that about 30% of infections are caused by people who do not know they have COVID-19 because they are asymptomatic or their symptoms have not appeared yet.

“So we don’t know who might spread it,” Blumberg says. “We do know social distancing reduces the risk of transmitting the virus by 90%, and wearing masks decreases the risk by 65%.

“Wearing a mask affects everyone,” he says. “If you care about your family or friends, or if you care about your community, wear a mask.”

Source: UC Davis

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Action averted 530 million COVID-19 infections

Emergency health policies in six major countries have “significantly and substantially slowed” the spread of COVID-19 and prevented hundreds of millions of new infections, according to new research.

The findings come as leaders worldwide struggle to balance the enormous and highly visible economic costs of emergency health measures against their public health benefits, which are difficult to see.

In the first peer-reviewed analysis of local, regional, and national policies, the researchers find that travel restrictions, business and school closures, shelter-in-place orders, and other non-pharmaceutical interventions averted roughly 530 million COVID-19 infections across the six countries in the study period ending April 6.

“…through our individual sacrifices, people everywhere have each contributed to one of humanity’s greatest collective achievements.”

Of these infections, 62 million would likely have been “confirmed cases,” given limited testing in each country.

Continuation of these policies after the study period has likely avoided many millions more infections, according to lead author Solomon Hsiang, director of the Global Policy Laboratory and a professor in the Goldman School of Public Policy at the University of California, Berkeley.

“The last several months have been extraordinarily difficult, but through our individual sacrifices, people everywhere have each contributed to one of humanity’s greatest collective achievements,” Hsiang says.

“I don’t think any human endeavor has ever saved so many lives in such a short period of time. There have been huge personal costs to staying home and canceling events, but the data show that each day made a profound difference. By using science and cooperating, we changed the course of history.”

The study evaluated 1,717 policies implemented in China, South Korea, Italy, Iran, France, and the United States in the period extending from the emergence of the virus in January to April 6, 2020. The researchers carried out their analysis while working under shelter-in-place restrictions.

Recognizing the historic challenge and potential impact of the pandemic, “everyone on our team dropped everything they were doing to work on this around the clock,” says Hsiang.

Avoiding more COVID-19 infections

The novel coronavirus emerged in late 2019 in Wuhan, China, and in a matter of weeks, spread around the globe. The medical impact was compounded by the devastating economic slowdown.

How great was the risk posed by the virus? Without comprehensive data on policy interventions, it would not have been possible to gauge how quickly it would have spread naturally. But according to the new study, COVID-19 infections were growing 38% per day on average—doubling roughly every two days in each country—before crisis policies slowed the spread.

“It’s as if the roof was about to fall in, but we caught it before it crushed everyone.”

Today, global COVID-19 cases are nearing 7 million, with just over 400,000 dead. But the research suggests that the toll would have been vastly worse without policy interventions.

“So many have suffered tragic losses already. And yet, April and May would have been even more devastating if we had done nothing, with a toll we probably can’t imagine,” Hsiang says.

“It’s as if the roof was about to fall in, but we caught it before it crushed everyone. It was difficult and exhausting, and we are still holding it up. But by coming together, we did something as a society that nobody could have done alone and which has never been done before.”

How well have COVID-19 policies worked?

Large-scale policies were initially deployed based on recommendations from epidemiological modeling teams that simulated the spread of COVID-19 under different sets of assumptions. But since both the pandemic and policy responses are unprecedented, nobody knew in advance which policies would work or how effective they would be.

The researchers studied how quickly the number of COVID-19 infections grew within different locations before and after policies were enacted, for the first time measuring how much each policy contributed to flattening the curve.

“…seemingly small delays in policy deployment likely produced dramatically different health outcomes.”

The researchers analyzed data on the number of confirmed cases in each country, based on local testing procedures. But to account for limited testing, they also calculated what the total infection rates likely would have been if everyone had been tested.

“Our results suggest that ongoing anti-contagion policies have already substantially reduced the number of COVID-19 infections observed in the world today,” the researchers write. “Based on these results, we find that the deployment of anti-contagion policies in all six countries significantly and substantially slowed the pandemic.”

During the period of study, the impact of policies the six countries is striking, both in statistical and human terms:

• China: policies averted roughly 37 million more confirmed cases, corresponding to 285 million total cases (including confirmed cases)
• South Korea: 11.5 million confirmed cases and 38 million total cases averted
• Italy: 2.1 million confirmed cases and 49 million total cases averted
• Iran: 5 million confirmed cases and 54 million total cases averted
• France: 1.4 million confirmed cases and 45 million total cases averted
• United States: 4.8 million confirmed cases and 60 million total cases averted

The study did not estimate how many lives might have been saved by the policies because, with so many infections, fatality rates would be much higher than anything observed to date.

The researchers based its conclusions on an exhaustive collection of data, gathered from hundreds of sources in several languages. The researchers traced the arrival of the virus in a given country, then used data to track how the cases grew over time. Noting when major policy interventions occurred, they were able to study how the numbers changed.

Lessons for the future

One objective of the study was to understand which policies have played the greatest role in slowing the pandemic.

The team found that home isolation, business closures, and lockdowns (a component of emergency declarations in some countries) often produced the clearest benefits. Travel restrictions and bans on gathering had mixed results, with large effects in some countries—Iran and France, respectively, for example—and less clear benefits in countries such as the United States.

The researchers did not find strong evidence that school closures had an impact in any country, but they caution that their finding is not conclusive, and that more research should be used to inform school policies.

The researchers found that while some policies change behavior immediately and may have quickly led to small benefits, it took three weeks, in general, for policies to achieve their full impact on the spread of COVID-19.

Now that some countries are relaxing policies, Hsiang says, “we might reasonably expect signals of any renewed spread to emerge on a similar two- to-three-week time frame.”

Lessons from the study can be valuable to more than 180 other countries not included in the analysis. While some countries have already reduced infection rates, confirmed cases in many others—such as Afghanistan, Bangladesh, Brazil, India, Pakistan, Peru, Mexico, Nepal, and Nigeria—are just starting to take off.

For these countries, one finding of the study stands out: “Our analysis of existing policies indicates that seemingly small delays in policy deployment likely produced dramatically different health outcomes.”

The researchers have made additional material, as well as data and code, available to the public.

Source: UC Berkeley

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