of the busiest travel days of the year. more now from cnn's tom foreman reporting from washington. >> reporter: the cdc announcement shortening isolation time came just hours after president biden admitted to the nation's governors covid testing has not kept pace with the omicron threat. >> it's not enough. it's clearly not enough. if we had known, we would have gone harder quicker if we could have. >> reporter: with covid cases soaring, more than 2,000 flights were grounded worldwide. nearly 3,000 delayed in the u.s. just today. at sea, several cruise ships have been infected, in some cases being turned away from ports, in all dampening the festivities. >> they weren't really enforcing masks until a lot of people started getting covid. then they were kind of enforcing masks more. i don't think he'll ever go on a cruise again honestly at this point. >> reporter: as the omicron variant rages, testing lines are stretching out and tests running short in some places.