I guess this has been already discussed here in /sci/ but but I don't usually lurk in this board:

Why there's no flu cases this year? I read an article in the media that said the use of masks and the social distancing is making the influenza virus unable to propagate between us.

Then why does Covid propagate regardless of the preventive measures? Aren't both viruses similar (viruses of the same family that attack the respiratory system)?