From what the first 5 weeks of my son returning to school in person, very little. Even with required masks the common cold is still making its way through his

From what the first 5 weeks of my son returning to school in person, very little. Even with required masks the common cold is still making its way through his classroom. We know this because each kid basically is out for a day to get tested for COVID than comes back. So instead of ten kids getting sick all at once, it's progressing through one or two at a time. Our current measures are blunting the spread of germs but by no means have we managed to hit a 'sterile' environment where there is no spread.