I've not read all the responses before this, can't be arsed
Droplet spread is very well known. Cough, sneeze, speach, even breathing project minute moisture droplets from nose and mouth. The droplets contain bacteria and viruses that may be present in the respiratory tract.
Even a simple very basic, single layer mask is an obstruction to some extent of droplet projection. Anyone that can't see this needs help.
Masks do not protect the wearer, they protect others from the wearer.
I will wear a mask whenever required and whenever I feel is appropriate out of respect for others. I am not going to get into fights about it.
Vaccines reduce the effects of the virus, they do not prevent infection. No other claim has been made. If you are double vaccinated you can still become infected, but you are much less likely to die or be seriously unwell. Every medication of any kind has side effects, even the humble aspirin. The nutters insist on all sorts of lunacy on this. People get blood clots even without vaccines.
There ya go. sorted.