with you. do you think some experts at this point say counting cases may not be the way to go, considering that omicron is less severe but more contagious, and do you think we should be talking about case numbers because it causes unnecessary panic? i do agree that critical matrix are deaths and hospitalizations, and infections are not relevant and we want to track those. doctor, thank you so much for your time. thank you, lindsay. chaos at airports as omicron and extreme weather disrupt travel nationwide. more than 1,800 flights canceled and thousands delayed. what you should know if you are traveling, next.
surveillance at four major u.s. airports to look for this new variant. we get more from cnn s nick watt. reporter: the question is when, not if the omicron variant reaches the united states. could already be here. among the first to study omicron, this guy. it looks like a problem, but we don t know to what extent it s going to be a problem. i wouldn t at this point say that this is hugely different from stuff we ve seen before. i think we ll get information on transmission and severity in the coming week or two. i do think it will take some time for us to get a better understanding on the impact of vaccines. our estimate is two to four weeks. reporter: here s what we already know about omicron s mutations. these mutations have been associated with increased transmissibility and immune-ivation. reporter: will it work as well against the delta variant?
big airports in the united states as the number of countries detecting the variant has climbed already to 20. cnn national correspondent nick watt has more on the new urgency, uncertainty, and all of this unfolding in the coronavirus pandemic. the question is when, not if the omicron variant reaches the united states. could already be here. among the first to study omicron, this guy. looks like a problem, but we don t know to what extent will be a problem. i wouldn t at this point say that this is hugely different from stuff we ve seen before. i think we ll get information on transmissibility and severity in the coming days, maybe a week or two. i think it will take some time for us to get a better understanding of the impact on vaccines. our estimate is between two and four weeks. here s what we already know about omicron s mutations. these mutations have been associated with increased
and countries cut off travel from south africa where the variant was first discovered. a doctor there told cnn s world s response has been an overreaction. cnn s nick watt starts our coverage. reporter: the question is when, not if, the omicron variant reaches the united states. could already be here. among the first to study omicron, this guy. it looks like a problem, but we don t know to what extent it s going to be a problem. i wouldn t at this point say that this is hugely different from stuff we ve seen before. i think we ll get some information on transmissibility and severity in the coming days, maybe a week or two. i do think it will take some time for us to get a better understanding of the impact on vaccines. our estimate is between two and four weeks. here s what we already know about omicron s mutations. these mutations have been associated with increased transmissibility and immune evasion.
discovered it. this was discovered by a couple of other groups in south africa. i m a virologist, so i don t look at i don t do the sequences. i take advice from those guys and i grow it up to see what it does. so i was in the office, he kind of showed me this stuff, and it was clear it was going to be a problem. what did you see that made it clear to you is going to be a problem? well, there s a whole bunch of mutations there. some of them are good for escaping the immune response. some of them are good for transmission. and some of them we didn t see before. of course, it looks like a problem, but we don t know to what extent it s going to be a problem. i wouldn t at this point say that this is hugely different from stuff we ve seen before. as i m beginning, as you know