Researchers looked at 14 types of face masks and calculated how effective they were at reducing coronavirus infection risk

Researchers tested coverings ranging from the kind worn by healthcare professionals to neck fleeces and knitted masks.

Since the beginning of the pandemic, the World Health Organization has stressed that, primarily, Covid-19 spreads through very close personal contact.

"Herd immunity" is a concept describing the point at which a population has developed protection against a disease.

If people washed their hands regularly, wore masks, and kept their social distance from each other, these three simple behaviors could stop most all of the Covid-19 pandemic,