An Overview on the Efficacy of Different Mask Varieties
By Kevin Chen
One of the most heavily debated topics during the COVID-19 pandemic involves the use of masks and amount of protection they provide. The World Health Organization (WHO) currently recommends wearing fabric masks in public spaces where social distancing is unable to be performed. The use of fabric masks does not apply to those with underlying medical conditions or those who are 60 years old or above. In those specific cases, medical masks are recommended instead.
The ideal fabric mask, as defined by WHO, is a mask that comprises of three separate layers: an outer hydrophobic layer to prevent droplets from entering the mask, a middle filter layer preferably made of polypropylene, and a inner hydrophilic layer in contact with the face to catch outgoing droplets. Medical masks, also known as surgical masks, are similarly triple layered, except that they are specifically manufactured to be used in a healthcare setting with non-woven fabric and may have additional features such as adjustable nose strips.
Two additional types of protection have come under scrutiny during the pandemic that were not mentioned in mask usage by WHO: N-95 respirators and neck gaiters.
N-95 Respirators
N-95 respirators are similar to medical masks with the exception that N-95 layers are designed to filter viruses and that N-95 respirators are designed to create a tight fit around the mouth and nose, unlike the looser medical mask. Currently, the CDC does not recommend N-95 usage by the general public as these specialized masks are reserved for healthcare professionals.
Neck Gaiters
Neck gaiters are tubes of cloth worn to cover the nose, mouth and neck, popularly used by athletes to keep warm while exercising. They have now reportedly been used as a popular substitute for cloth masks as a method of coverage. A very recent study published this year on a new methodology of measuring droplet expulsion with different varieties of masks resulted in neck gaiters demonstrating a higher average amount of droplet expulsion when talking than wearing no mask. Although the study is flawed and does not prove a generalized statement that gaiters are worse than having no mask, neck gaiters are not recommended as they do not provide the specialized layers of WHO recommended fabric masks.
In terms of how efficient these masks are, there is mixed evidence for their efficacy on protection against COVID-19. Most recent published research on mask efficacy has only been performed involving other viral infections, and many of the studies cannot be applied with one hundred percent certainty.
Regarding fabric masks versus medical masks, one of the most cited randomized clinical trials on this topic was published in 2015 and tested the efficacy of cloth masks versus medical masks for healthcare workers in larger, more specialized hospitals. The results indicated a significantly higher rate of infection for those wearing cloth masks versus those wearing medical masks. However, the main type of virus detected from participants with symptoms of infection were rhinoviruses, which are smaller and different in structure than coronaviruses. All other viruses were detected no more than four times in any participant group, whether that be with a medical mask or fabric mask. In addition, the cloth masks used in the experiment consisted of only two layers — both made of cotton, a hydrophilic material, which differs from the three different layers of different properties recommended for fabric masks by WHO.
In terms of the efficacy of medical masks versus N-95 respirators, a review published in April of this year found four different studies dealing with the efficacy of medical masks (n=3957) vs N-95 masks (n=4779) for healthcare workers on patients with “acute febrile illness,” or flu-like symptoms. Tests for multiple viruses were done, but only one study performed testing for coronavirus infection, which did not include the novel SARS-CoV-2 virus. All studies demonstrated that there were no significant differences in viral infection rates of those who wore medical masks and those who wore N-95 masks under “routine care and non–aerosol‐generating procedures.”
There has been a lack of studies involving the usage of no mask versus any mask due to ethical concerns, but it can be inferred through past data that wearing an approved mask in public conditions would provide much better protection than an unapproved mask or no mask at all. With the current state of the pandemic in the United States, controlling the spread of this disease is a global health concern and should be treated accordingly.
Sources
[1] Coronavirus disease (COVID-19) advice for the public: When and how to use masks (WHO)
[2] N95 Surgical Respirator (Filligent)
[3] Low-cost measurement of face mask efficacy for filtering expelled droplets during speech (Emma P. Fischer et al., Science Advances)
[4] N95 Respirators, Surgical Masks, and Face Masks (U.S. Food & Drug Administration)
[5] A cluster randomised trial of cloth masks compared with medical masks in healthcare workers (C Raina MacIntyre et al.)
[6] Medical masks vs N95 respirators for preventing COVID‐19 in healthcare workers: A systematic review and meta‐analysis of randomized trials (Jessica J. Bartoszko et al.)
Visit our website at thinq.med.ucla.edu and follow us on Facebook and Instagram @uclathinq!
