The Week That Wasn't in COVID-19: Humidity, Face Shields

Ellie Kincaid


August 21, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

This week in COVID-19 news, scientists said they had confirmed a link between humidity and SARS-CoV-2 transmission and that the use of face shields seemed to eliminate infections among community health workers in India. But you didn't see these headlines on Medscape Medical News. Here's why.


Ambient humidity could influence the spread of SARS-CoV-2, according to new research. Analyzing records from 1200 cases of COVID-19 in the Australian state of New South Wales, researchers from the University of Sydney and Fudan University in Shanghai found that a 1% decrease in relative humidity was associated with a 7% to 8% increase in daily COVID-19 cases. "Information generated in this study confirms humidity as a driver of SARS‐CoV‐2 transmission," they wrote.

Perhaps, but if so, there's little clinicians can do to control the weather. Plus, the researchers did not know what humidity levels people were experiencing when they became infected with SARS-CoV-2 ― they used data from meteorologic recording stations in the postal codes where patients lived and assumed the persons became infected when outdoors or that conditions were similar enough indoors. This methodology is common in environmental health studies, but it requires some big assumptions that may or may not be accurate.

Face Shields

A group of community health workers in Chennai, India, who visited the homes of people in which a family member had tested positive for COVID-19 to counsel them about quarantining unwittingly provided an opportunity to assess the efficacy of face shields as personal protective equipment (PPE). Initially, the workers' PPE consisted of alcohol hand rub, three-layered surgical masks, gloves, and shoe covers. Workers started getting sick, and 12 of 62 tested positive for COVID-19. After the remaining 50 workers started using face shields as well, none of them contracted the virus.

It's good news that these community health workers eventually got the PPE they needed to be safe, and that it was effective. But this description of their experience doesn't dramatically change the state of knowledge about PPE, including face shields ― when workers have it, it works ― so we didn't highlight it for our readers.

Ellie Kincaid is Medscape's associate managing editor. She has previously written about healthcare for Forbes, the Wall Street Journal, and Nature Medicine. She can be reached at or on Twitter @ellie_kincaid.

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