Experts have been recommending face masks as a way to prevent the spread of the coronavirus; The wearer of the face mask can protect those around him by blocking respiratory drops, which have been identified as a primary means of transmission of COVID-19. But could wearing a face mask also protect the user? It’s a possibility, according to a new article by researchers from the University of California, San Francisco and John Hopkins, to be published in the Journal of General Internal Medicine.
The document relies on “virological, epidemiological and ecological evidence” to argue that the use of a face mask could result in a “viral dose” or a smaller amount of coronavirus particles, which a user exposed to the virus could absorb. And according to several studies cited by researchers, a lower viral dose can lead to less severe symptoms, or even no symptoms, of a given disease, including COVID-19.
A cited study published in May tested this with coronaviruses and hamsters. The researchers in China installed hamster cages, some infected with coronaviruses and others healthy, and separated the two groups with partitions of surgical masks in some of the cages. Citing this study, UCSF and Johns Hopkins scientists noted that healthy hamsters were “less likely to contract SARS-CoV-2 infection with a surgical mask partition,” and those who did have a milder infection compared with his “unmasked” “companions.
The researchers also looked at large-scale coronavirus data from before and after facial masking was widely practiced. They noted that a pre-masking review estimated that 15 percent of COVID-19 cases were asymptomatic. A more recent review has put that number as high as 40-45 percent, and the CDC has agreed that asymptomatic infection is around 40 percent. In the closed environment of a cruise ship, this narrative has also developed. An estimate in March put the asymptomatic infection rates on the Diamond Princess cruise ship at around 18 percent. On a more recent cruise, all passengers and staff received masks after a positive case was identified on board. While 128 of 217 passengers finally tested positive, 81 percent of them remained asymptomatic.
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While this evidence is indirect, the researchers turned to it to hypothesize that facial masks could play a role in increasing the proportion of cases that are asymptomatic, which, while problematic for transmitting the virus, could help communities to achieve collective immunity without large numbers of serious cases.
And it could even go beyond that, they suggest. Again, pointing out that the evidence was indirect and likely affected by multiple factors, the researchers noted that countries with population-level masking have been more successful in reducing COVID-19 mortality rates. In fact, even when cases have re-emerged in these areas with population-based masking upon reopening (eg, South Korea, Singapore, Hong Kong, Taiwan), the case fatality rate has remained low with openness but masking, “the researchers wrote. Their argument is that masking can not only lead to a higher proportion of asymptomatic coronavirus cases, but can also decrease death rates.
Again, asymptomatic infection is a double-edged sword. The researchers wrote that it can increase the spread of the virus, but at the same time, “exposing society to SARS-CoV-2 without the unacceptable consequences of serious illness … could lead to increased immunity at the community level and decrease the spread as we wait for a vaccine. ” And they add that “the masks, depending on the type, filter most of the viral particles, but not all”, which increases the possibility of a less dangerous asymptomatic infection compared to a serious infection.
Much of the cited evidence does not establish a short, dry correlation between cause and effect between masking and a lower viral dose, and between masking and asymptomatic infections. in a New York Times In the article on the document, some experts expressed caution about the findings, while others said it makes “complete sense” that the masking would protect the user to some degree. While more research is needed to finalize the UCSF-Johns Hopkins findings, the document provides another motivation to continue masking: not only does it protect others, but it can also extend a safety measure for you, the wearer of the Mask as well. .
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