2,700 people ordered to self-quarantine. gillian steinberg is one of them. >> ideally, we'll be back in school next week. >> reporter: she teaches english at sar academy in the bronx, where one of the lawyer's children attends school. it's now shut down. what is your biggest concern now as this outbreak spreads? >> i think there are vulnerable populations who genuinely have to be worried for their physical health, but i think that we just have to be careful not to overreact. >> reporter: tonight, mayor de blasio telling any new yorker who recently returned from five hard-hit countries to immediately self-quarantine. governor cuomo activating a statewide emergency operation center in albany and two outposts in westchester county. >> what is going to happen is, the number will continue to go up. it must, because we are continuing to test more and more. >> reporter: and now a health care worker in new jersey testing positive. a man in his 30s, recovering in the hospital, one of two cases