Blue to blue-green indicate less virus spread and
yellow-green to red indicates increasingly out of control virus spread
Research is continuing to come out with evidence that wearing face masks in public is the best protection against COVID-19 currently available.
Results from humans
A paper from Texas A&M analyzed spread of the virus among people wearing cloth face masks compared to those who did not. The paper, Identifying airborne transmission as the dominant route for the spread of COVID-19, analyzed infection trends in view of mitigation measures in Wuhan, China, Italy, and New York City, from January 23 to May 9, 2020. The analysis indicates that the difference with and without mandated face covering shapes the pandemic trends in all three study areas.Airborne transmission of the virus in droplets was found to be the most common route of transmission among people. Wearing face masks in public significantly reduces the transmission rate. Social distancing in the US was insufficient by itself in limiting virus spread. The researchers conclude: "wearing of face masks in public corresponds to the most effective means to prevent interhuman transmission." They argue that face masks coupled with social distancing, quarantine, and contact tracing, appears to be the best means practical to stop the COVID-19 pandemic.
In an interview, one of the researchers commented: "Our work suggests that the failure in containing the propagation of COVID-19 pandemic worldwide is largely attributed to the unrecognized importance of airborne virus transmission. Social-distancing and washing our hands must continue, but that's not sufficient enough protection. Wearing a face mask as well as practicing good hand hygiene and social distancing will greatly reduce the chances of anyone contracting the COVID-19 virus."
Computational biology: Modeling virus spread
Another paper, A modelling framework to
assess the likely effectiveness
of facemasks in combination
with ‘lock-down’ in managing
the COVID-19 pandemic, describes computer modeling analyses that included modeling the effects of wearing face masks in public. The model allows researchers to set and test various parameters that influence COVID-19 spread from person to person. The parameters that were analyzed include (i) comparing populations in lock downs compared to non-lock down populations, and (ii) effects of different levels of effectiveness of facemasks in stopping droplet escape from people and in preventing droplet transfer to other people.The authors write: "Our results are illustrated for a number of plausible values for parameter ranges describing epidemiological processes and mechanistic properties of facemasks, in the absence of current measurements for these values. We show that, when facemasks are used by the public all the time (not just from when symptoms first appear), the effective reproduction number, Re, can be decreased below 1, leading to the mitigation of epidemic spread. ..... Under certain conditions, when lock-down periods are implemented in combination with 100% facemask use, there is vastly less disease spread, secondary and tertiary waves are flattened and the epidemic is brought under control. The effect occurs even when it is assumed that facemasks are only 50% effective at capturing exhaled virus inoculum with an equal or lower efficiency on inhalation."
The authors also commented: "A key message from our analyses to aid the widespread adoption of facemasks would be: ‘my mask protects you, your mask protects me’." In other words, an infected person who wears a cloth facemask spreads less virus and an uninfected person who wears a facemask is exposed to less virus, both of which reduces virus spread.
At present some countries do not require wearing facemasks in public, but the accumulating research evidence suggests that is probably a major mistake. The researchers comment that their analyses could explain why some countries with a facemask requirement had significantly lower rates of COVID-19 spread and associated deaths.
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