Study Did Not Find That Masks Do Not Work

CLAIM: A 2018 study that looked at the effectiveness of N95 masks versus medical masks found that masks don’t stop the spread of viruses.

THE FACTS: The study found that N95 masks and medical masks are equally effective at protecting against viral respiratory infections and illnesses — not that masks do not work.

The trial tracked groups of health care workers who were randomly assigned to wear either N95 or medical masks, also known as surgical masks, when around patients with respiratory or influenza-like illnesses. It looked at the health outcomes of these health workers at 137 outpatient sites over four flu seasons.

Derek Cummings, a professor of biology and infectious disease epidemiologist at the University of Florida, said the study built on previous research showed masks are effective at preventing the spread of viruses.

“The study was not designed to assess whether N95 masks work or not,” he said. “What we were trying to do was to say that we know N95s work. We don’t know how much better they are than medical masks.”

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