Here are links to some posts on the other ‘Safe-for-Work’ Blog.
If we use that criteria all respiratory viruses fall into two groups: a] those who use the respiratory tract to gain entrance to body and cause systemic infections (measles, mumps, rubella, chickenpox etc) and b] those who infection is largely confined to the linings of respiratory tract (rhinoviruses, coronaviruses, influenza etc). So why does this distinction matter?
As it turns out, non-surface viral proteins which are not involved in viral infectivity nonetheless also provide targets for the T-cells, including those involved in formation of immune memories. So even a virus with a partial “escape” mutation in its surface proteins/s will still trigger the T- cell mediated part of immune system and kickstart the immune response.
Normal surgical or cloth face masks, on the other hand, have no chance of stopping airborne bacteria and viruses. At best, they are effective at reducing the formation of small droplets created by the wearer when speaking or breathing. For your information- surgeons wear surgical masks to reduce the chance of small droplets (larger than 2-4 μm) which contain bacteria from their nose and mouth from ending up in opened tissue during surgical procedures.