Surgical and cotton masks may not prevent spread of Covid 19 infection, finds study

Researchers at Seoul, South Korea have found that both surgical and cotton masks were found to be ineffective for preventing the dissemination of SARS-CoV-2 from the coughs of patients with COVID-19.

The study conducted at two hospitals in Seoul, South Korea, found that when COVID-19 patients coughed into either type of mask, droplets of virus were released to the environment and external mask surface. A brief research report is published in Annals of Internal Medicine.

During respiratory viral infection, face masks are thought to prevent transmission, leading health care experts to recommend their use during the COVID-19 pandemic. With a shortage of both N95 and surgical masks, which have been shown to prevent the spread of influenza virus, cotton masks have gained interest as a substitute. However, it is not known if surgical or cotton masks worn by patients with COVID-19 prevent contamination of the environment.

Researchers from Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea instructed 4 patients with COVID-19 to cough 5 times each onto a petri dish while wearing the following sequence of masks: no mask, surgical mask, cotton mask, and again with no mask. Mask surfaces were swabbed with aseptic Dacron swabs in the following sequence: outer surface of surgical mask, inner surface of surgical mask, outer surface of cotton mask, and inner surface of cotton mask. The researchers found SARS COV-2 on all surfaces. These findings suggest that recommendations to wear face masks to prevent the spread of COVID-19 may not be effective.

This experiment did not include N95 masks and does not reflect the actual transmission of infection from patients with COVID-19 wearing different types of masks. We do not know whether masks shorten the travel distance of droplets during coughing. Further study is needed to recommend whether face masks decrease transmission of virus from asymptomatic individuals or those with suspected COVID-19 who are not coughing.

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:http://annals.org/aim/article/doi/10.7326/M20-1342