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article imageEssential Science: Why masks work and time to end the debate?

By Tim Sandle     Oct 19, 2020 in Science
How effective are face masks? The body of evidence in favour of masks continues to grow. In this week’s Essential Science, we consider a diverse array of different literature that looks at mask wearing in different contexts.
It may not be high on Donald Trump’s agenda, but the medical consensus is firmly siding on wearing masks in the context of the coronavirus pandemic. Despite this, there remains a large number within the global community who are unconvinced.
Man wearing face mask during the COVID-19 outbreak.
Man wearing face mask during the COVID-19 outbreak.
Yet reducing disease spread requires not one, but two things. The first is with limiting contacts of infected individuals, which can be achieved through social distancing. The second measure is to reduce the transmission probability per contact. With this second measure, the use of the facemask is important.
Man wearing a face mask when outside  in the time of coronavirus.
Man wearing a face mask when outside, in the time of coronavirus.
Before leaping into the evidence for masks, it is important to point out that Masks, depending on the material and design, filter out a majority of viral particles, but not all. Another factor is the type of mask, especially given that masks differ in their maximum internal leakage rate limit. The common surgical masks, and the type easiest to get hold of, are designed to protect against larger droplets or particles. Given that the SARS-CoV-2 virus is small, with a diameter of 60–140 nm, then the standard masks cannot provide a complete barrier.
While N95 masks will protect the wearer from 90 percent of airborne particles, that could be carrying the coronavirus. In contrast, surgical masks are 67 percent effective in protecting the wearer.
Respirator mask for excluding viruses and chemicals.
Respirator mask for excluding viruses and chemicals.
However, surgical masks are effective in terms of protecting people from large droplets and sprays. It is as larger droplets that most viral particles are ejected from an infected person, via these larger sized pathogen-transporting droplets and aerosols.
What most scientists think
According to an article on the Nature website, by Lynne Peeples, the scientific consensus is firmly with facemasks saving lives during the pandemic. Peeples writes: “research shows that they cut down the chances of both transmitting and catching the coronavirus, and some studies hint that masks might reduce the severity of infection if people do contract the disease.”
Wearing masks works
A recent study, studying an array of data, finds that weekly increases in mortality (based on statistics normalized for per head of the population) were four times lower in places where masks were the norm, compared with other regions (especially regions where mask wearing did not represent government advice).
Vending machine selling face masks and hand sanitizers. Blackfriars station  London  UK.
Vending machine selling face masks and hand sanitizers. Blackfriars station, London, UK.
The study is titled “Association of country-wide coronavirus mortality with demographics, testing, lockdowns, and public wearing of masks.”
In the study multivariate analysis was used to consider mask wearing together with an array of different factors. These factors included: age, sex, obesity prevalence, temperature, urbanization, smoking, duration of infection, lockdowns, viral testing, contact tracing policies, and public mask-wearing norms and policies
The case of the hair stylists
Some evidence about the effectiveness of masks arises from a report that looked at two hair stylists who were diagnosed with COVID-19 are working in a salon. Although they went home after and subsequently infected other members of their family, no one who was being beautified in the salon become infected (based on those who agreed to be tested).
Interestingly, A total of 139 clients were directly serviced by stylists A and B from the time they developed symptoms until they took leave from work, with no cases of infection being reported.
How not to social distance? New form of face mask tested.
How not to social distance? New form of face mask tested.
This case appears in a publication issued by the CDC, titled “Absence of Apparent Transmission of SARS-CoV-2 from Two Stylists After Exposure at a Hair Salon with a Universal Face Covering Policy - Springfield, Missouri, May 2020.”
Protest to survive?
A second case study looks at protestors. One question that springs to mind during any marches or rallies that occur during COVID-19 is whether those taking part, in close contact and who do not wear masks, are at a greater risk.
An abandoned facemask on a field in the UK.
An abandoned facemask on a field in the UK.
For example, at one rally in the U.S. for Black Lives Matter, where the participants had the sense to wear masks, the rally did not trigger spikes in infections among those present, see: “Black Lives Matter Protests, Social Distancing, and COVID-19 NBER Working Paper 27408”. However, at a summer camp in Georgia, where moat present did not adorn masks, the infection rate was relatively high. The summer camp case is presented in “SARS-CoV-2 Transmission and Infection Among Attendees of an Overnight Camp - Georgia, June 2020.”
Reducing infection rates
Perhaps the most important of the new research relating to make usage, which comes from the University of California, is the finding that masking reduces the dose of virus a wearer might receive. The impact of this is infections that are milder or even asymptomatic. This now appears to be supported by virologic, epidemiologic and ecologic evidence.
Face mask discarded in lab coat pocket.
Face mask discarded in lab coat pocket.
The study is published in the Journal of Internal Medicine and it is titled “Masks Do More Than Protect Others During COVID-19: Reducing the Inoculum of SARS-CoV-2 to Protect the Wearer.”
Mask shortages
Where there is a shortage of masks, then the focus should be foremost with mask-wearing by infectious people (so-termed "source control"), rather than mask-wearing by susceptible people.
Face mask on a table - an unsafe practice?
Face mask on a table - an unsafe practice?
This message forms part of the following video:
And where masks are available? Wear one but bear in mind it cannot provide a total solution. Always remember to keep that 2 metre distance, as the number one protective measure.
Essential Science
This article is the latest in Digital Journal’s Essential Science series. Each week we consider a topic of interest relating to each of the core fields in science, presenting an important subject in the form of a digestible read.
Hurricane Laura over the US state of Louisiana
Hurricane Laura over the US state of Louisiana
Handout, NOAA/GOES/AFP
Last week the topic was hurricanes, with predictions indicating that this year’s hurricane season is expected to see more storms than is typical together with storms of greater intensity. It appears that climate change is the reason for this.
The week before the topic was neglected diseases. Schistosomiasis (or bilharzia) causes significant ill-health effects to millions of people. The disease is caused by a parasitic worm. In the article, the latest research was discussed and assessed.
More about coronavirus, Covid19, Infection, face mask, Face covering
 
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