Since the beginning of the mask discussion in the United States, the mixed messaging has been baffling. Or, more accurately, the swing from ‘surgical masks don’t work’ to ‘use a bandana or scarf’ because it’s better than nothing is striking, and reflects the dire challenge of this coronavirus time: there’s simply not enough personal protective equipment (PPE) to go around to those who need it, including hospital staff on the front lines. Today, we are going to dive a bit deeper into what surgical masks do and don’t do as well as address do-it-yourself (DIY) masks. To be clear, we agree with public health experts that medical masks should be reserved for medical staff on the front lines, those in healthcare who have face-to-face contact with the general population, people who are symptomatic or living with someone who is, and people who are immunocompromised. People working in behavioral health crisis and outpatient treatment facilities fall under this protected category.
Up until about mid-March, experts were pleading with healthy people to stop hoarding and wearing masks. The gist was that while surgical masks can filter out droplets, they don’t filter out small, viral particles. On February 29th, the U.S. Surgeon General, Dr. Jerome Adams tweeted that surgical masks aren’t effective in protecting against COVID-19.
Seriously people- STOP BUYING MASKS!
They are NOT effective in preventing general public from catching #Coronavirus, but if healthcare providers can’t get them to care for sick patients, it puts them and our communities at risk!
— U.S. Surgeon General (@Surgeon_General) February 29, 2020
It’s true that surgical masks don’t entirely protect from small, viral particles, but that’s not the same as they don’t work. They do work, just not 100%. Some studies have estimated surgical masks provide protection roughly five times better than no barrier; other studies have also shown protection but not to that same degree. Sure, surgical masks don’t block out aerosols entirely, but they do create substantial protection.
Furthermore, fit and adherence to properly putting on any of the masks and taking them off matters in their efficacy.
“Will a surgical mask protect me against someone’s cough or sneeze?”
The Center for Infectious Disease Research and Policy reported in February that no one has yet done the National Institute for Occupational Safety and Health (NIOSH) studies “that simulate the cough big droplets that land 3 to 6 feet away from a person or the little droplets that can travel long distances and in air handling system.” (NIOSH is a division of the CDC.) That means, until then, experts are looking to what they know about other coronaviruses’ behavior for guidance.
According to Dr. Marianne van der Sande and her colleagues, a typical human cough is made up of half large, half small droplets, the latter of which are more effective in the transmission of respiratory infections. However, the researchers note there needs to be “more detailed analysis of aerosol and droplet inoculation” to give better insight on transmission.
What hospitals and medical workers have done in Hong Kong and Singapore during the coronavirus outbreak—both countries are having a shortage of N95 respirators—is use surgical masks unless they are performing procedures, like intubating a patient known or suspected to have COVID-19, where “respiratory secretions can be aerosolized.” Both of their methodologies have helped to flatten the curve in their nations using their countermeasures. They only use N95 respirators, instead of surgical masks, in instances where “respiratory secretions can be aerosolized” like during intubation.
So, from their perspective, surgical masks sufficiently protect against infection from droplets that result from a cough or sneeze, and the fact that they have used this methodology and successfully flattened their curves is reassuring. Of course, they both are using a multi-prong effort to combat COVID-19, including social distancing, screening, testing, and tracking down contacts of people identified with the virus.
Note: Hong Kong has recently experienced a spike in infection—not because it’s countermeasures, which are effective, but because it loosened its rules last week, allowing people to go to work, the gym, and dine out, and opened its borders to permit residents to return home.
Do DIY Masks Work? All Three Masks Measured Against One Another
The short answer is yes, but how much isn’t clear and likely varies depending on how they are made and what they are made out of. A 2008 study found that surgical masks were about twice as effective as homemade masks, while the European equivalent of an N95 mask were 50 times more effective than homemade masks and 25 times more so than surgical masks. Another study found that surgical masks were 3 times better at blocking transmission than homemade masks, though both “significantly reduced the number of microorganisms expelled.”
The conclusion from the experts is that a DIY mask is a “last resort” to prevent respiratory infection transmission, but that it does create a barrier far better than none at all.