a New Research Lancet Face coverings have been shown to significantly reduce the amount of SARS-CoV-2 in an infected person’s breath, by up to 98 percent, depending on the type of face covering worn.
This study is the first to measure viral shedding in infected humans with and without face coverings in a realistic setting where masks and respirators are used. Previous studies have only used mannequins. Volunteers who participated in the study were not trained or provided with fit testing or extensive instructions on how to use masks or respirators to best limit virus spread.
The end result is that this study fairly accurately replicates real-world conditions of face covering selection and use, and the measured viral load reductions represent what one could realistically expect without significant efforts to fit, test, and train the entire population on proper use.
Another important strength of this study is that we directly measured the amount of virus in the breath of the same subjects at the same time, with and without a face covering, so each subject served as his or her own control. Moreover, capturing the virus in the breath allowed us to determine the specific strain of virus that subjects were infected with.
The study enrolled 106 volunteers between June 2020 and May 2022. Of these, 44 provided 60 same-day samples, one with and one without a face covering, of which at least one had detectable levels of SARS-CoV-2 virus.
The face coverings examined in the study were N95 and KN95 respirators as well as cloth and surgical masks. Study volunteers were randomly assigned to wear cloth masks or bring their own cloth masks. The majority of the KN95 respirators tested were provided to students and employees by the University of Maryland (where the study took place). The surgical masks and N95 respirators tested were also provided to volunteers, so most were one brand of device.
The study evolved over time from comparing cloth masks to surgical masks to comparing KN95 masks to surgical masks to KN95 masks to N95 masks. Of the 60 total paired samples, 8 were made with cloth masks, 26 with surgical masks, 13 with KN95 masks, and 13 with N95 masks.
The authors had previously published the results of this study. Lancet For the first time, results for N95s and nearly all KN95s are included.
The researchers used a bioaerosol collector that captures human exhaled breath to collect each sample over a 30-minute period. Volunteers were instructed to speak specific phrases and sing at specific intervals over the course of 30 minutes to mimic the typical aerosols produced by vocalization.
The study found that wearing an N95 mask reduced the amount of virus in exhaled breath by an average of 98%, a greater reduction than all other masks and respirators. KN95 masks reduced viral load by 71%, cloth masks by 87%, and surgical masks by 74%. Cloth masks significantly outperformed both KN95 and surgical masks. The difference in reduction between KN95 and surgical masks was not significant.
Overall, the study volunteers were a young population with mild COVID-19 symptoms. The omicron variant of SARS-CoV-2 was predominant, detected in 29 samples. The alpha and delta variants were detected in four samples each.
Based on previous studies of viral load measurements and the amount of virus typically needed to cause infection, the researchers estimated that when an infected person wears an N95 mask, they are 20 times less likely to transmit the virus.
The researchers explained why KN95 masks performed poorly in their study, because they primarily studied one brand, and therefore the results are not generally representative of all KN95 masks. They noted that the brand of KN95 mask they studied had an unfortunate combination of stiffness and high resistance to airflow. The stiffness of the masks likely led to a poor fit, creating large air gaps through which infectious aerosols could pass relatively unimpeded. The high resistance to airflow makes it more likely that air will flow through the gaps created by the poor fit, rather than through the mask’s filters.
The study is limited in that it focused on younger people with mild symptoms, and it studied a specific mask manufacturer, so the results cannot necessarily be generalized to all N95s, KN95s, surgical masks, or cloth masks.
Nonetheless, the study demonstrated that all face coverings tested were effective in reducing infectious aerosols produced by individuals infected with SARS-CoV-2.
“The research shows that any mask is better than no mask, and the N95 is far better than other options. That’s the No. 1 message.” Dr. Donald Milton said:He is the lead author of the study.
This study provides strong evidence supporting mandatory policies for wearing face coverings as part of comprehensive measures to control the pandemic, and therefore is an essential tool in any strategy to eradicate SARS-CoV-2.
The study authors strongly advocate for health care workers to wear N95 masks to protect patients, visitors, and other health care workers.
“Duckbill N95 masks should become the standard of care in high-risk settings such as nursing homes and health care settings,” said Dr. Jianyu Lai, lead author of the study.
This study again The Unscientific Nature of the CDC Guidelines Regarding wearing a mask, the CDC also The guidance was changed in March of this year. The period for wearing masks after ending COVID quarantine has been reduced from 10 days to just 5. Like previous changes, this change in guidelines is politically motivated and has no scientific basis.
Mask requirements for health care workers are also being lifted across the country, with both health departments and the health care systems they work for dropping mask requirements. New York State Department of Health lifts mask mandate In May, for healthcare workers.
The study was supported by the North Carolina Legislature. Overrode the governor’s veto Bans on masks have been passed there. Mask bans are also in various stages of consideration in New York state, Chicago and Los Angeles. Bills have been introduced in New York and Chicago, and the mayor of Los Angeles has proposed a mask ban.
These mask bans are intended to stifle anti-genocide protests. Notably, North Carolina’s mask ban also holds protest organizers liable for injuries sustained during protests and increases penalties for blocking roads during protests.
Only the working class can establish scientifically based control over COVID-19 and other infectious diseases, including establishing a solid basis for mask-wearing obligations. The working class must achieve this by seizing power and implementing its own independent political program that prioritizes social necessity, not private profit, as the economic driver of society.
