Is There Evidence for this Intervention?
People that have respiratory symptoms or fever should stay home and not be out and about right now (with or without a mask).
Cloth masks or home-made masks and scarfs are fine for asymptomatic persons to wear in the community (but likely provide little protection for the wearer or community members).
Members of the community should not wear manufactured medical masks if they are asymptomatic. Doing so puts additional pressure on the PPE supplies and putting additional strain on health care workers.
However, cloth masks might remind people to stop touching their faces and also remind people to keep their distance from others (perhaps the mask can provide a visual queue to keep some distance).
The CDC is now recommending the voluntary use of cloth face masks by everyone in the community regardless of whether they’re sick.
There is some evidence to support the use of cloth masks for people that have any respiratory symptoms (during this pandemic) as a recent study supports the use of surgical face masks to prevent coronavirus transmission from symptomatic individuals. There’s widespread consensus that people working in healthcare and people that have any respiratory symptoms in the community should wear facemasks. But- there’s little if any evidence to support the use of face masks for those who are not symptomatic in the community.
Given the shortage of PPE in healthcare settings and the demand that would be placed on the supply chain from widespread use of manufactured medical masks, the only reasonable recommendation is for people without symptoms to wear cloth masks, scarves or homemade masks- not manufactured medical masks.
There’s very limited data on the efficacy of cloth masks. There are some small studies (1, 2, 3) showing that cloth masks can provide some level of marginal protection against particles which can contain viruses. If a covering gets wet (even from the moisture emitted when a person exhales) the fabric could be more likely to transmit the virus.
One randomized trial compared medical masks, 2-layer cotton cloth masks, and usual practice in hospital health care workers (n=1607). The cloth masks were 2-layer cotton masks. Participants were asked to wash them daily with soap and water. The study found that the highest rates of influenza-like illness were in the cloth mask group (RR =13.0 compared to the medical mask wearers).
Infections were also higher in the cloth mask group compared to the usual practice group. Cloth masks also had higher rates of laboratory confirmed virus in participants (RR 1.7 compared with the medical mask group). Penetration of cloth masks by particles was almost 97% compared to 44% in medical masks.