“We’re seeing a lot of magical thinking, a lot of wishful thinking,” says Lisa Brosseau, retired professor of environmental and occupational health sciences at the University of Illinois at Chicago School of Public Health. Cloth masks offer no protection from COVID-19 she says. “Cloth masks are wishful thinking.”
A nationally recognized expert on infectious diseases (she studied Ebola aerosol transmission) and respiratory protection in healthcare settings, Brosseau wrote a commentary for the University of Minnesota’s Center for Infectious Disease Research and Policy. “We do not recommend requiring the general public who do not have symptoms of COVID-19-like illness to routinely wear cloth or surgical masks because: There is no scientific evidence they are effective in reducing the risk of SARS-CoV-2 transmission.
“Sweeping mask recommendations will not reduce SARS-CoV-2 transmission, as evidenced by the widespread practice of wearing such masks in Hubei province (China). Given the paucity of information about their (cloth masks) performance as source control in real-world settings, along with the extremely low efficiency of cloth masks as filters and their poor fit, there is no evidence to support their use by the public or healthcare workers to control the emission of particles from the wearer.”
As to why the CDC “recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain,” Brosseau told Infection Control Today on April 25: “I don’t understand the CDC’s recommendations. What’s interesting to me is if you look at the references that were listed on under their recommendation, none of them have anything to do with masks or the performance of masks or the performance of their filters or any of that. They’re all references related to pre-symptomatic or asymptomatic transmission.”
“People say, well, they worked in Asia. There’s no evidence that they worked in Asia. In fact, it’s very clear that the healthcare workers in China, they may have been wearing cloth masks to start with, but when you look at pictures of what they were wearing later, they were wearing respirators. They were wearing full face gear and body gear and gloves.”
“I’m seeing more and more people now wearing cloth masks on the streets. I don’t have a problem with people wearing them. I just want them to understand that they aren’t very much more protective than if they weren’t wearing them. And they’re really not doing a whole lot of good for the people around them. We should continue to do social distancing as much as we possibly can.”
Brosseau says both surgical and cotton masks seem to be ineffective in preventing the dissemination of SARS–CoV-2 from the coughs of patients with COVID-19 to the environment and external mask surface.
“Data suggest that surgical masks worn by the public will have no or very low impact on disease transmission during a pandemic. There is no evidence that surgical masks worn by healthcare workers are effective at limiting the emission of small particles or in preventing contamination of wounds during surgery.”
“The only thing that provides personal protection for the person wearing the mask is a respirator. And that is the thing that healthcare workers should be wearing. The best protection in that case is for the healthcare worker to wear a respirator.”
A new study in the Annals of Internal Medicine found that surgical and cotton masks are both ineffective when it comes to blocking droplets of the virus SARS–CoV-2 that may be generated when somebody coughs, according to investigators with the Ulsan College of Medicine, Seoul, South Korea.
Four patients coughed 5 times each into a petri dish while wearing no mask. They then coughed 5 times wearing a surgical mask, a cotton mask, and then, again, wearing no mask. The study, conducted at 2 hospitals in Seoul, found that when patients coughed into either type of mask, droplets of SARS–CoV-2 were released into the environment. The research investigators found greater contamination on the outer surface of the face masks than on the inner surfaces.
The study did not include the N95 masks.
Coronavirus particles are spheres with diameters of approximately 0.125 microns. The smallest particles are 0.06 microns, and the largest are 0.14 microns. According to a review in American Industrial Hygiene Association Journal N95 masks remove 95% of all particles that are between 0.1 to 0.3 in diameter. An N95 will filter aerosols and droplets.
In the UK, Dr. Jenny Harries, England’s deputy chief medical officer, warned in March that it was not a good idea for the public to wear facemasks as the virus can get trapped in the material and causes infection when the wearer breathes in.
“You can actually trap the virus in the mask and start breathing it in. What tends to happen is people will have one mask. They won’t wear it all the time, they will take it off when they get home, they will put it down on a surface they haven’t cleaned.”
“For the average member of the public walking down a street, it is not a good idea,” Dr. Harries said. “Face masks are needed if you are a patient and are symptomatic and if you’re a healthcare worker and social care worker.” When asked on April 23 whether people should wear masks in crowded places such as on public transport, Dr Harries said the “evidence is very difficult to tease out.” She said it was possible there could be “a very, very small potential beneficial effect in some enclosed environments”.
The World Health Organization in early April reported that there is no evidence wearing a mask (whether medical or other types) by a healthy person in a community setting can prevent infection with respiratory viruses, including COVID-19. It also said there is limited evidence that a person wearing a mask in households or while contacting sick patients or attending mass gatherings may be beneficial as a preventative measure. In healthcare settings workers using cloth-only masks were at an increased risk.
Then the WHO changed course, somewhat. “There may be situations where the wearing of masks may reduce the rate at which infected individuals may infect others,” the WHO’s Dr Michael Ryan said. “We will support governments who wish to have a measured approach to the use of masks and who include that as part of the comprehensive strategy to control this disease.”
The WHO’s latest advice as of April 26 – Currently there is not enough evidence for or against the use of masks (medical or other) for healthy individuals in the wider community. If you are healthy, you only need to wear a mask if you are taking care of a person with COVID-19. Wear a mask if you are coughing or sneezing.