players testing positive. it is important to note, though, most of these are asymptomatic cases. here's the thing, here in new york city tonight, "hamilton" is now the sixth broadway show to cancel a performance due to covid this week. so joining me now to discuss this is the medical director for the national foundation for infectious diseases. good evening, doctor. this is, i think, getting bad here. i don't want to alarm people, but we should take some precautions. it's not just the nfl going through this, the nba postponing games due to covid for the first time this season. why are we seeing so many cases like this? >> well, don, covid has done it again. it's thrown us a curve, high and tight. and it's called omicron. and this is an extraordinarily infectious variant. even more infectious than delta. and although our vaccines look