A recent study conducted at two different hospitals in Seoul, South Korea, revealed that surgical and cotton masks were ineffective in the filtering of SARS-CoV-2 from the coughs of patients with COVID-19.
The study found that when COVID-19 patients coughed into either type of mask, droplets of the virus were released to the environment and external mask surface. The research report has been published in the journal Annals of Internal Medicine.
For the study, COVID-19 patients were instructed to cough onto a petri dish containing viral transport media, both by wearing and without wearing a mask. The patients were asked to cough 5 times without a mask, with a surgical mask, cotton mask and then again without mask onto each petri plates. The outer and inner surfaces of the surgical masks and cotton masks were then swabbed using an aseptic dacron swab and tested.
The study found that all swabs from the outer surfaces of the masks were positive for SARS–CoV-2, whereas most swabs from the inner mask surfaces were negative. The median viral loads after coughs without a mask, with a surgical mask, and with a cotton mask were 2.56 log copies/mL, 2.42 log copies/mL, and 1.85 log copies/mL, respectively.
The findings suggest that recommendations to wear face masks including surgical and cotton masks to prevent the spread of COVID-19 may not be effective, although the study emphasizes avoiding touching of the mask surfaces after wearing.
However, the authors noted that the 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.