COVID-19 Update: Ineffective Surgical Masks / WHO Guidance on Masks / More Evidence on Convalescent Plasma

By Amy Orciari Herman

Edited by David G. Fairchild, MD, MPH, and Lorenzo Di Francesco, MD, FACP, FHM

Surgical and cotton face masks appear ineffective for blocking SARS-CoV-2 when COVID-19 patients cough, according to a small study in the Annals of Internal Medicine.

Four patients with COVID-19 in South Korea coughed onto petri dishes about 20 cm (8 inches) away while not wearing a mask, then wearing a surgical mask, then a cotton mask, and then no mask again. Researchers measured viral load in the petri dishes and also from swabs taken from the outside and inside of the masks.

For three patients, the petri dishes had detectable virus when surgical masks were worn, and for two patients, petri dishes were also positive when cotton masks were worn. Additionally, for all patients, the outer surface of both masks was positive for SARS-CoV-2 (the inner surface didn't always have detectable virus).

In related news, the World Health Organization has issued new guidance on using face masks during COVID-19. The group emphasizes that "the use of a mask alone is insufficient to provide an adequate level of protection, and other measures should also be adopted," such as hand hygiene and physical distancing. The WHO notes that medical masks should be reserved for healthcare workers and for people with symptoms, as well as caregivers in the same room as an infected person. It also offers advice on safe mask removal: untie it from behind (don't touch the front) and wash your hands immediately after disposal.

In other COVID-19 news:

• The CDC is offering a personal protective equipment (PPE) burn rate calculator to help healthcare facilities estimate how long their current supply will last. Give it a try at the CDC link below.

• A study in the Proceedings of the National Academy of Sciences adds to evidence supporting use of convalescent plasma to treat COVID-19. Ten patients in China with severe disease received a 200-mL infusion of inactivated convalescent plasma from recovered donors. All symptoms in all patients "disappeared or largely improved" within 1 to 3 days. Viral load was undetectable within 7 days in seven patients who'd had viremia. There were no serious adverse reactions.