Warn CDC experts that face masks are far more protective against COVID-19 than face shields

Researchers at the US Centers for Disease Control and Prevention (CDC) have found that face masks and neck gaiters are far more than face shields in reducing the emission of respiratory aerosols that can transmit severe acute respiratory syndrome 2 (SARS). We conducted a study that showed that it seemed to be effective. -CoV-2).

SARS-CoV-2 is the cause of the current coronavirus disease 2019 (COVID-19) pandemic and continues to pose a continuing threat to global public health and the economy.

The team used a cough aerosol simulator to release small aerosol particles into various facial coverings, and N95 respiratory organs, procedure masks, cloth masks, and neck gaiters effectively reduced aerosol emissions, but face shields. Discovered that it wasn’t.

“Our results suggest that face masks and neck gaiters are preferred over face shields as a source controller for cough aerosols,” writes William Lindsley and colleagues.

Preprinted paper is available on the server medRxiv*, While the article is undergoing peer review.

Cough aerosol simulator system for source control measurements. This system is an aerosol generation system, a bellows and linear motor to generate a simulated cough, a flexible skin head foam with a face mask, neck gaiter, or face shield, 105 liters of aerosol coughing. It consists of a collection chamber. Andersen impactor for collecting aerosol particles separated by size.

Community infections can occur through infected aerosol droplets

SARS-CoV-2 can be transmitted from person to person through a large respiratory aerosol (greater than about 10 µm in diameter) produced when an infected person coughs, sneezes, breathes, talks, or sings. ..

However, smaller aerosols are also released during these activities, and short-range aerial viral infections may be possible.

To protect against this potential local transmission route, various public health agencies, including the CDC and the World Health Organization (WHO), have recommended that the general public wear face masks or other face covers as source control devices. Recommended.

“Source control devices are intended to protect others from the infectious aerosols released by the wearer, as compared to personal protective equipment such as the N95 respiratory system, which is primarily intended to protect the wearer. “The team explains.

However, researchers often dislike wearing face masks, and their compliance levels may be low and inconsistent, researchers say.

Repeated removal and replacement of the mask and continued adjustment can contaminate your hands. This can lead to viral infections, especially if the mask is reused.

Face shield was proposed as an alternative

In the opinion piece Journal of American Medical AssociationResearchers have suggested that face shields may be more effective in reducing community infections because they are more comfortable and are therefore more likely to be widely adopted.

However, few studies have considered face shields as a source control device. Effectiveness It’s missing.

What was included in the current study?

Lindsley et al. Now use a cough aerosol simulator to emit clouds that simulate small breathing aerosols (0-7 µm in diameter) onto various types of facial covers, of particles that can move within and around each device. Evaluated the amount.

Researchers tested the collection efficiency (percentage of aerosols blocked by the device) of N95 respiratory, medical treatment masks, commercial three-layer cloth masks, polyester neck gaiters, and commercial disposable face shields.

Neck gaiters are worn as a single layer of fabric or as a folded two-layer fabric. In the experiments conducted in this study, researchers tested both configurations.

Face masks and gaiters were much more effective than face shields

On average, the N95 respiratory system stopped the release of 99% of the total cough aerosol into the environment, the surgical mask blocked 59%, and the cloth mask blocked 51%.

Neck gaiters blocked 47% of cough aerosols when worn as a single layer and 60% when worn as a double layer.

Face shields, on the other hand, stopped only 2% of cough aerosols from being released into the atmosphere.

There was no significant difference in the collection efficiency of treatment masks, cloth masks, and neck gaiters, but all of these devices were significantly more effective than face shields.

“Our results show that face covers are more effective than face shields as a public health measure to reduce SARS-CoV-2 community infections and as a source control device to reduce the emission of respiratory aerosols into the environment. It suggests that, “the team concludes.

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they are not peer-reviewed, guide clinical / health-related behaviors, and should not be treated as established information.