It is important to note that patients with COVID-19 are more infectious in the first days of the disease , and that those first days may show few symptoms of having become ill, if not none.
In this way, prophylaxis seems to be a systemic need because we simply often do not know if we are sources of contagion or not.
When we speak, small micro-droplets are expelled through the mouth. If you are infectious, these droplets carry virus particles . Only the largest droplets end up surviving before drying up into droplets that are 3-5 times smaller than the original droplet.
If you have COVID-19 and you cough at someone at a distance of 8 inches, wearing a cotton mask will reduce the amount of virus you transmit to that person by more than 90%.
Is it mandatory to use them?
How to get all or most people to wear masks? You can try to educate the citizenry or try to persuade them, but a more effective approach is to require them to wear a mask, whether in specific settings such as public transport or grocery stores or even at all times outside the home.
Some have claimed that getting people to wear masks will encourage risky behavior (eg, going out more, washing hands less), with a net negative result .
Similar arguments have been made before for HIV prevention strategies and motorcycle helmet laws. However, real-world research on these topics suggests that although some people respond with riskier behaviors, at the population level there was an overall improvement in safety and well-being .
While not all scientific evidence supports the use of masks (for example, an experimental study in four participants who were asked to actively cough into Petri dishes showed that the use of surgical or cotton masks did not prevent dispersion of the particles of the SARS-Cov-19), most point in the same direction . The evaluation of this evidence leads us to a clear conclusion: keep your droplets of saliva to yourself, wear a mask.