coronavirus vaccine. that's so important, because we can't keep, you know, sort of dealing with variant after variant after variant, and the universal vaccine would work on all of them, they've been trying to do that for flu for many, many years, and that hasn't happened. hopefully it could happen with coronavirus. and also, kate, what we're expecting now is for the senators to grill hhs, the department of health and human services, and the fda, about why we are experiencing a shortage of home tests two years into the pandemic. kate? >> elizabeth, thanks so much. we will be sticking close to this and bring you all of the big moments as there are some tough questions coming at these officials. appreciate it, elizabeth. let's focus in right now though on chicago where hundreds of thousands of students are expected to return to class tomorrow. the school district and teachers union reaching a tentative deal overnight, on these safety protocols, that had been keeping everyone out of class to this point. cnn's adrian broadus is live in chicago with more on this. what are the details here?