https://www.scientificamerican.com/arti ... nfections/
While mere inconveniences for most people, respiratory viruses like the seasonal flu are responsible for missed work and school. In some cases they can lead to severe illnesses, especially in very young children and older adults. After years of fighting one virus, parents are now exhausted by the reality of battling many, many more.
But there is a straightforward way to cut down on the risk for ourselves and others. When it comes to individual decisions, masks are among the most low-cost and most effective steps that can be taken to broadly reduce transmission of a multitude of viruses.
Long before the COVID-19 pandemic, researchers were studying the effectiveness of masks at reducing transmission of other respiratory viruses. Meta-analyses of viral spread during the original SARS epidemic in 2002-2003 showed that one infection was averted for every six people wearing a mask, and for every three people who were wearing an N95 mask.