- Surgical and cotton masks may be of questionable utility in preventing SARS-CoV-2 air droplet dissemination from coughs of patients with COVID-19, according to findings in this small study.
Why this matters
- WHO continues to state that evidence supporting community use of face masks is limited, particularly for healthy individuals living or in contact with persons who have tested positive for SARS-CoV-2.
- Patients should follow national guidance, including proper wearing, removal, and disposal of masks, as well as related proper hand hygiene after touching outer mask surfaces.
- 4 patients were instructed to cough 5 times under each mask condition onto a Petri dish containing 1 mL viral transport media.
- Test sequence: no mask, surgical mask, cotton mask, no mask.
- Swab sequence: outer and inner swabs for each mask type.
- Funding: Fund Project for Infectious Disease Research, Republic of Korea.
- Median sample viral loads (log copies/mL):
- Nasopharyngeal: 5.66.
- Saliva: 4.00.
- Median Petri dish viral loads (log copies/mL) after a cough:
- No mask: 2.56.
- Surgical mask: 2.42.
- Cotton mask: 1.85.
- In 3 of 4 tests of the surgical and cotton masks, the inner surfaces of the masks were negative.
- Outer mask surfaces were positive after all tests, with ranges of 2.11-2.63 log copies/mL for the surgical masks and 2.58-3.61 log copies/mL for the cotton masks.
- Only 4 patients included.
- N-95 masks not tested.
- Transmission dynamics not reflected.