New CDC Advice as of April 3
CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies) especially in areas of significant community-based transmission.
It is critical to emphasize that maintaining 6-feet social distancing remains important to slowing the spread of the virus. CDC is additionally advising the use of simple cloth face coverings to slow the spread of the virus and help people who may have the virus and do not know it from transmitting it to others. Cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure.Recommendation Regarding the Use of Cloth Face Coverings, Especially in Areas of Significant Community-Based Transmission
We should all be wearing improvised cloth masks when we go out in public places, to reduce our risk of catching COVID-19 and our risk of transmitting COVID-19.
Wearing an improvised mask is not an alternative to staying six feet away from other people. It just helps further reduce risk.
It is now officially recognized that we can spread the virus when we don’t know we have it, either because we have no symptoms yet or because our symptoms are too mild to pay attention to. We all have the responsibility to help others by reducing the spread.
Any mask, even a well-wrapped T-shirt, makes it easier for us to follow the standard advice to “avoid touching your eyes, nose and mouth with unwashed hands“. Following that advice makes us less likely to transfer the virus from our hands to a point that the virus can actually enter our body. It also makes us less likely to put the virus on our hands and transfer it to surfaces for others to pick up. Eyes are not usually covered by a mask, but a mask can help us remember not to rub our eyes.
Any mask can also reduce the extent to which we spread droplets of saliva and mucus when we speak enthusiastically, clear our throats, or cough or sneeze.
At the beginning of the epidemic, the official advice was contrary: the general public should not be wearing masks. The underlying motivation for that order was clear: People working on the front lines of the battle against the virus are at vastly greater risk than the general public and have a vastly greater need for professional grade personal protective equipment (“PPE”). Only a properly-applied professional-grade mask can fully protect a person from fine particles containing virus that could be in the air near an infected person.
Right now there is a world-wide shortage of PPE that is putting health care workers at acute personal risk. If the general public were advised to use PPE, then affluent people who go out only to shop would stock up on scarce professional-grade PPE for their own self care. This would make it harder to supply the necessary PPE for doctors, nurses, EMTs, and others who are in constant close contact with very sick people.
Massachusetts’ leaders have put procurement of PPE for health care workers at the very top of their daily priority list and we are making progress. Governor Baker scored a huge breakthrough working with the Kraft family to bring 1 million masks from China. Partners Healthcare acquired a machine that can recycle 80,000 masks per day.
I am hopeful that as the surge of sick patients washes into the hospitals, our front-line workers will have the equipment they need, but we are nowhere close to having professional grade equipment for all seven million Masssachusetts citizens. It would be a safety improvement for everyone on the street to be wearing professional grade masks. Maybe in a few months, as American manufacturing ramps up, we can get to that place: If you think about the volume of disposable food packaging we use, reasonable quality masks for everyone is not out of reach in the future.
For now, the Center for Disease Control is saying that we should all be doing our part by wearing what we have or can make at home: a ski mask or scarf, a cut up T-shirt, the old dust masks we may have from our last home improvement project, or, if we have the skills, a nicer mask made from any of the many patterns popping up on the internet now.
Personally, my biggest reluctance to wear a mask is that it could send a message that I am afraid of or unwelcoming towards other people. But if more people start wearing masks, my hope is that we can start to hear a different message from a mask: I care enough about you to take the risk of looking silly.
Will it really help?
As can be seen from the resources listed below, public health authorities are divided, with U.S. and European official authorities leaning against recommending masks but Asian authorities recommending them. The differences in policy may partly reflect immediate availability of domestic manufacturing capacity for masks or may reflect cultural differences.
Disease transmission is complicated and the science may not offer clear guidance for public policy. For example, a recent WHO study of non-pharmaceutical interventions in influenza pandemics endorsed the following often repeated recommendations despite finding no specific evidence of their effectiveness in reducing influenza transmission:
- Hand hygiene (“[randomized controlled trials] have not found that hand hygiene is effective in reducing transmission of laboratory-confirmed influenza”)
- Respiratory etiquette (“no evidence that this is effective in reducing influenza transmission”)
- Surface and object cleaning (“no evidence that this is effective in reducing transmission”)
- Face masks (“no evidence that this is effective in reducing transmission”)
The point is not that these recommendations are not valid. Rather that “mechanistic plausibility” plays an important role in public health decision making. The absence of evidence for the effectiveness of a measure is not the same as evidence of absence of effectiveness.
It is “mechanistically plausible” to believe that home-made cloth masks might reduce the probability of transmission of COVID-19 by some material amount. In the dismal mathematics of our current pandemic, the possibility of even a slight reduction in transmission rates seems worth the very modest effort involved in improvising and wearing masks.
Do it yourself guides
- How to sew a facemask (NY Times)
- It’s Time to Make Your Own Mask (NY Times)
- How to make a mask (Wisconsin Children’s)
- Simple DIY face mask-making tips to fight against coronaviris (East Bay Times)
- How to make a Face Mask (Deaconess)
- No-Sew Pleated Face Mask with Handkerchief and Hair Tie
- Simple face covering demonstrated by Surgeon General (covers face, but too thick to breath through)
Official Advice from our Health Authorities
- WHO: Wear masks only if you are sick or caring for someone who is sick.
- CDC: Wear cloth face coverings in public settings where other social distancing measures are difficult to maintain.
- MDPH: Wear masks only if you are sick or caring for someone who is sick.
Official Advice from other Health Authorities
- South Korea: Wear masks and change masks every day.
- Japan: Distributing masks to all families (backlash: not enough masks), although official advice to wear facemask is weak and applies only to confined spaces
- China: Public in densely populated settings should wear disposable medical masks (viewed using Google Translate)
- Hong Kong: general public should wear a surgical mask when taking public transport or staying in crowded place
Critiques of and Expected Evolution of Domestic Official Advice
- Why Telling People They Don’t Need Masks Backfired
- Every American should wear a face mask to defeat Covid-19
- A Lesson from Japan’s Fight against Coronavirus: Masks Help
- Face Masks Are In
- Top Chinese Scientist: The big mistake in the U.S. and Europe, in my opinion, is that people aren’t wearing masks.
- White House divided about facemasks
- Trump administration moves toward recommending broader use of face masks
- Should I Make My Own Mask?
- Papers about the Efficacy of Basic Masks see also the youtube talk by the authors of the collection of papers.
- The Case for Universal Cloth Mask Adoption — key citations located:
- Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic?
- Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review.
- Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles
- Professional and home-made face masks reduce exposure to respiratory infections among the general population
- Atlantic: Everyone thinks they’re right about masks
- Consumer Reports: What to Know Now About Masks and Coronavirus
- Review of national facemask policies in Lancet: “Community transmission might be reduced if everyone, including people who have been infected but are asymptomatic and contagious, wear face masks.”
- Minnesota Center for Infection Disease Research Policy: “Given the paucity of information about their 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”
- Use of cloth masks in the practice of infection control – evidence and policy gaps “Although cloth masks are commonly used in low/middle income countries, there is minimal policy acknowledgment of the need for cloth masks, and a lack of evidence on their efficacy and use.”