biden in the rose garden late today celebrating the news, calling it a, quote, great milestone, a great day for america. thanking americans for getting us to this point, pointing to the vaccinations.e presidt sayis can w wt e known an smile at o. he and the vice president doing just that today, walking back into the white house together without masks, without social distancing. the cdc director dr. rochelle walensky making the point today that this is based on science. more data emerging in just the last week, that vaccinations work against the variants. 12 to 15-year-olds can now get the vaccine and tonight, more than 152 million adults have received at least one dose, that's nearly 59% of adults and about one-third now of all americans. but there were immediate questions. if you're fully vaccinated, can you still transmit the virus to others without knowing? and if you're in one of those crowds or back at work, how do you know if someone near you has been vaccinated or not and does that pose a risk? dr. jen ashton answering those questions in just a moment. we have it all covered for you tonight, beginning with abc's whit johnson right here in new york. >> reporter: tonight, a giant step