(CNN) - Cloth masks are better than nothing at protecting people from disease, but they don’t compare to medical-grade masks.
A study in the journal Emerging Infectious Diseases said cloth masks should not be used by healthcare professionals.
The findings come from the only clinical trial study of cloth versus medical grade masks which was conducted in Vietnam.
While it took place before the emergence of the coronavirus, it did focus on healthcare workers exposed to influenza-like illnesses.
Respirators, a special fitted kind of mask and medical-grade N-95 type face masks showed a much lower risk of infection in the study.
However, some cloth masks proved to be better than others.
Many factors, such as thread count, number of layers, type of fabric and water resistance can play a role in the quality of protection, but the study’s key message is that they should be used as a last resort when medical masks and respirators are not available.