Experts recommend face masks as a way to prevent the spread of coronavirus; the wearer of a face mask can protect people around them because it masks respiratory drops that have been identified as the main means of COVID-19 transmission. But could a face mask also protect the wearer? This is an opportunity, according to a new contribution by scientists from the University of California – San Francisco and John Hopkins, which will be published in the Journal of General Internal Medicine.
The article draws on “virological, epidemiological and ecological evidence” to argue that wearing a face mask could lead to a lower “viral dose” or amount of coronavirus particles that a user exposed to the virus would receive. And according to several studies cited by scientists, a lower viral dose can lead to less severe or even no symptoms of the disease, including COVID-19.
One cited study published in May tested it for coronaviruses and hamsters. Researchers in China assembled hamster cages, some of which were infected with coronavirus and others healthy, and separated the two groups with sections of surgical masks in some of the cages. Citing this study, UCSF and Johns Hopkins noted that healthy hamsters were “less likely to become infected with SARS-CoV-2 infection with a surgical mask” and those who had a milder infection compared to their “unmasked” peers.
The researchers also examined extensive coronavirus data from before and after face masking. According to preliminary masking, it was estimated that 15 percent of COVID-19 cases were asymptomatic. According to the latest review, this number is up to 40-45% and the CDC agrees that the asymptomatic infection is about 40%. This story also took place in the closed environment of a cruise ship. An estimate in March put the rate of asymptomatic infection on the cruise ship Diamond Princess at about 18 percent. During the recent voyage, all passengers and staff received masks after a positive case was detected on board. While 128 of the 217 passengers finally tested positive, 81 percent of them remained asymptomatic.
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Although this evidence is indirect, scientists believed that face masks could play a role in increasing the proportion of asymptomatic cases which, although problematic for virus transmission, could help communities achieve herd immunity without a large number of serious cases.
And it could even go further, as they suggest. The researchers again noted that the evidence was indirect and probably influenced by several factors. However, the researchers noted that countries with masking at the population level were more successful in reducing COVID-19 mortality rates. “Although cases of population-based masking have re-emerged in these areas when reopened (eg South Korea, Singapore, Hong Kong, Taiwan), mortality rates initially remain open but are being masked,” the researchers said. They argue that masking may not only lead to a higher incidence of asymptomatic coronaviruses, but may also ultimately reduce mortality.
The asymptomatic infection is again a double-edged sword. The researchers wrote that they could increase the spread of the virus, but at the same time “exposure of SARS-CoV-2 without the unacceptable consequences of serious diseases … could lead to greater immunity at the community level and slow the spread because we are waiting for a vaccine. They add that “masks, depending on the type, filter out most, but not all, of the virus particles,” increasing the likelihood of a less dangerous asymptomatic infection than a serious one.
Much of the cited evidence does not establish a cutting and dry correlation of causes and consequences between masking and lower doses of the virus and between masking and asymptomatic infections. IN New York Times article on article, some experts expressed caution about the conclusions, while others said it made “complete sense” that masking would protect the user to some extent. While further research is needed to suppress the UCSF-Johns Hopkins conclusions, the document provides additional motivation to continue camouflage: not only does it protect others, but it can also extend the level of safety for you, those who wear the mask as well.
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