cases, with infections increasing in more than half the country and deaths up 11%. >> the increasing trends in cases, hospitalizations and deaths are very concerning, and they threaten the progress we've already made. >> reporter: one big reason: variants-- particularly the one that originated in the united kingdom. at this columbia university lab, dr. david ho first identified yet another variant circulating in new york city. >> it's concerning because it's spreading at a rate that is on par with the u.k. variant, and we know the u.k. variant is more transmissible and more-- more lethal. >> reporter: it's being blamed for nearly half the new infections here in the past week. new york state has the second highest number of new cases in the country, something governor andrew cuomo addressed today. >> it is not over. it is better, but it is not over. >> reporter: and now the c.d.c. says they're investigating two more cases of blood clots in people who received the johnson