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Facial Masking for Covid-19 — Potential for “Variolation” as We Await a Vaccine

As SARS-CoV-2 continues its global spread, it is possible that Kovid-19, one of the pillars of epidemic control – universal facial masking – may help reduce the severity of the disease and ensure A large proportion of new infections may be asymptomatic. If this hypothesis originates, then universal masking can become a form of “virtualization” that will create immunity and thereby slow the spread of the virus to the United States and elsewhere, as we await a vaccine.

An important cause of population-based facial masking became apparent in March, when reports began to describe the high rate of SARS-CoV-2, which was flowing through patients’ noses and mouths that were painful or asymptomatic. Were – equal shedding rate among those symptomatic patients.1 Universal facial masking seemed a possible way to prevent transmission from asymptomatic infected people. The Centers for Disease Control and Prevention (CDC) therefore recommended on April 3 that clothing cover in areas with high rates of community broadcasting in public – a recommendation disproportionately followed in the United States.

Past evidence related to other respiratory viruses indicates that preventing the viral particles from entering the nose and mouth can also protect the wearer of a facial mask from becoming infected.2 Worldwide epidemiological investigations – particularly in Asian countries that had become accustomed to population-wide masking during the 2003 SARS epidemic – have suggested that there is a strong link between public masking and epidemic control. Recent data from Boston suggest that SARS-CoV-2 infection among healthcare workers decreased after universal masking was implemented in municipal hospitals in late March.

SARS-CoV-2 has the protein potential to cause numerous clinical manifestations, ranging from complete reduction of symptoms to pneumonia, acute respiratory distress syndrome, and death. Recent virologic, epidemiological, and ecological data have led to the hypothesis that the severity of the disease may also decrease among those infected with facial masking.3 This possibility is consistent with the long-standing theory of viral pathogenesis, which assumes that the severity of the disease is proportional to the viral inoculum. Since 1938, researchers have explored, primarily in animal models, the concept of a lethal dose of the virus — or the dose at which 50% of exposed hosts die (LD50). With viral infections, in which host immune responses play a major role in viral pathogenesis, such as SARS-COV-2, high doses of the viral inoculum may decrease innate immune defenses and increase disease severity. In fact, regulating immunopathology is a mechanism by which dexamethasone improves the outcomes of severe Kovid-19 infection. As evidenced by the concept of viral inocula affecting disease manifestations, higher doses of administered virus led to more severe manifestations of Kovid-19 in a Syrian hamster model of SARS-CoV-2 infection.4

If the viral inoculum matters in determining the severity of SARS-CoV-2 infection, an additional envisaged cause of wearing a face mask would be to reduce the viral inoculum to which the wearer is exposed and the disease has a later clinical effect . Since the mask can filter out droplets containing some viruses (with a filtering capability determined by the mask type),2 Masking can reduce the inoculum it gives to an exposed person. If this theory accepts population-wide masking with any type of mask, which increases acceptance and adherence,2 SARS-CoV-2 may contribute to increase the proportion of infections that are asymptomatic. The specific rate of asymptomatic infection with SARS-CoV-2 was estimated to be 40% by CDC in mid-July, but the rate of asymptomatic infection is reported to be over 80% in settings with universal facial masking, which This hypothesis provides observational evidence. Countries that have adopted population-wide masking perform better in terms of severe Kovid-related illnesses and mortality, suggesting a shift from symptomatic to asymptomatic infections in environments with limited testing. . Another experiment in the Syrian hamster model mimicked surgical masking of animals and showed that fake masking is less likely to infect hamsters, and if they become infected, they are either asymptomatic or without masks in them. There are symptoms of planted hamsters.

The most obvious way for the society to overcome the devastating effects of Kovid-19 is to promote measures to reduce both transmission and severity of the disease. But SARS-CoV-2 is highly communicable, it cannot be included by syndromic-based surveillance alone,1 And it is proving difficult to eradicate such areas, even those areas that implemented drastic initial control measures. Due to the recent increase in testing demand, efforts to increase testing and prevention in the United States are ongoing and have been successful so far.

The expectation of vaccines rests not only on infection prevention: most vaccine trials include a secondary consequence of reducing the severity of the disease, as the proportion of cases in which the disease is mild or asymptomatic increases, a public health victory. Will be. Universal masking seems to reduce the rate of new infections; We hypothesize that by reducing the viral inoculum, it will also increase the proportion of infected people who remain asymptomatic.3

For example, in an outbreak on a closed Argentine cruise ship, where passengers were provided with surgical masks and staff with N95 masks, the rate of asymptomatic infection was 81% (as in earlier cruise ships without universal masking Compared to 20% in outbreaks of). In two recent outbreaks at US food processing plants, where all workers were issued masks each day and required to wear them, the proportion of asymptomatic infections among the more than 500 people was 95%, each in Was 95% with only 5%. Outbreak of mild to moderate symptoms.3 Case-fatality rates in countries with compulsory or enforced populations remain low, even with a resurgence of cases after lockdown.

Differentiation was a procedure under which people susceptible to smallpox were vaccinated with material taken from the vesicle of a person with smallpox with the intention of causing a mild infection and subsequent immunity. Variation was practiced only until the introduction of the Varola vaccine, which eventually eradicated smallpox. Despite concerns related to safety, worldwide delivery, and eventual uptake, the world has high expectations for a highly effective SARS-CoV-2 vaccine, and as of early September, 34 vaccine candidates were in clinical evaluation, Which had hundreds more in development.

We await the results of vaccine trials, however, any public health measure that can increase the ratio of asymptomatic SARS-CoV-2 infections can make both infections less lethal and the population without serious diseases and deaths -Wide can increase immunity. Re-engagement with SARS-CoV-2 appears to be rare, despite prevalence over 8 months worldwide and as suggested by the Macaque model. The scientific community has been clarifying for some time the humor and cell-mediated components of the adaptive immune response to SARS-CoV-2 and the inadequacy of antibody-based seroprevalence studies to estimate more durable T-cell and memory B levels is. Cell immunity to SARS-CoV-2. Promising data is emerging in recent weeks suggesting that strong cell-mediated immune outcome results from mild or asymptomatic SARS-CoV-2 infection:5 Therefore any public health strategy, which can reduce the severity of the disease, should increase population-related immunity.

To test our hypothesis that population-wide masking is one of those strategies, we need further studies comparing rates of asymptomatic infection in areas with and without universal masking. To test the variability hypothesis, we will need more studies comparing the strength and durability of SARS-CoV-2-specific T-cell immunity between people with asymptomatic infection and those with symptomatic infection, as well as the natural slowing of SARS A demonstration of being. -CoV-2 spread to areas with a high proportion of asymptomatic infections.

Ultimately, combating the epidemic would have to reduce both transmission rates and disease severity. Increasing evidence suggests that population-wide facial masking may benefit both components of the response.

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