started doing people that were younger than 16. you remember their vaccine is for 16 and older. but as you mention, let me show you, this is some of the youngest trial participants that we've now heard. over 6,000 people age 6 months to 11 years. and then you have 3,000 adolescents, age 12 to 17 years. what's happening now is they're going to trial these, again, very young participants with various doses of the vaccine. 25 micro gram, 50 microgram, 100 mi microgram. they're trying to figure out two things, is this safe in people of that age and what is the right dose to give as well. after that, if those things sort of -- if they get the information they need and sprois proven safe, they can bridge these trials to existing trials. meaning, hey, we get a lot of information. they could get some results early. as you heard, dr. fauci said by the fall potentially high school students potentially could have a vaccine. >> i was going to ask you about the timeline there. so if this goes well, sanjay, this would mean when for shots in arms? >> well, you know, so think of it like this, the closer you are in age to the existing trial, so high school students, for example, closest in age to the existing trials of people who are adults, they're probably going to be fastest. and that's because a lot of the data sort of will be able to be extrapolated to that age group more easily. for people who are younger, again, they're still going to be using these bridging trials, but that will probably take a bit longer. so we're talking end of the year, maybe beginning of next year for, you know, the youngest, 6 months to 11 years. >> just one more point on the youngest children. one of the things at least in my reading over the last couple months, too, is the questions about how young for vaccinations because of the way that young children seem to respond to the virus versus slightly older children, which they start to hit later elementary school into middle school. how much is that coming into play here? >> well, it's a very interesting and important question. i've talked to lots of people who have been on the vaccine production side of things and say, look, what are the goals here? are the goals going to be different with the vaccine for young people versus older people? so, for example, we have said for some time that the vaccine we know primarily prevents illness, hospitalizations, deaths. older people are going to be more at risk of those things. younger people far less at risk. but what is the role of their transmission of the virus? this is something that's still a question that comes up all the time around school debates, for example. so as the vaccine going to be something that's more at sort of decreasing infection and transmission? is that the goal? is that the outcome they're really looking for in younger people. if so, it can take longer to get those results. that's the sort of thinking that goes into this. >> on the subject of vaccines, i want to make clear this is an issue right now in europe in other parts of the country because i'm talking about the astrazeneca vaccine which is not approved for use in the united states. several european countries have suspended use of it because some people who had taken it, a very limited number of people who had taken the vaccine, sanjay, correct me if i'm wrong, had experienced certain kinds of blood clotting. what exactly does this mean? what doesn't it mean? and what's your assessment of these countries stopping the use of a vaccine which may very well be saving lives? >> well, what i would say first of all and, you know, we spent a fair amount of time talking to people who are on sort of the regulatory side of this. the antennas are up very high. what i mean is that this is a new product that's going out into the world. so this sort of safety monitoring of this is really high. you're going to catch everything at this point. and then after you catch things you have to say, what did i just catch? is this meaningful or not. that's the phase we're in right now. two things i think jumped out at me when i started looking at some of these reports, one is that the overall background incidents of people just developing blood clots for all sorts of different reasons is maybe even higher than what we're seeing among the vaccinated population. people do get sick as a general rule in a general population vaccine or no vaccine. so, the second thing that popped out is that the nature of the clots among this vaccine seemed to be a little different than what you normally expect with spontaneous blood clotting. so why is that? is that somehow related to the vaccine? right now there is no cause and effect here. this is purely an association and a very, very small one. 17 to 20 million people have now received this vaccine and we're talking i think a couple of dozen, maybe 30 people who have had these sorts of blood clots, really small number. but they're going to assess it. the world health organization weighed in. i want you to read what they said about this because they're already showing their feelings about this. there is no evidence that the incidents are caused by the vaccine and it is important the vaccination campaigns continue so we can save lives and stem severe disease from the virus. the european medical agency is going to meet on thursday and hopefully render some sort of conclusion on this. for the very reasons you mentioned. you can't stall this too long. makes sense. antenna is up. you have to assess and move on quickly. >> i want to play a little bit of what dr. walensky, now director of the cdc had to say yesterday in terms of her concerns for where we are as a country. >> we have seen footage of people enjoying spring break festivities maskless. this is all in the context of still 50,000 cases per day. i'm pleading with you for the sake of our nation's health, these should be warning signs for all of us. cases climbed last spring, they climbed again in the summer, they will climb now if we stop taking precautions when we continue to get more and more people vaccinated. >> this is really not the first time we've heard that urgency, certainly not from her and yet we still do see those pictures. i mean, are you concerned about the message being lost at this point? do you think it's getting through? >> you know, i think it's getting through to a certain segment of the population but maybe not enough people are heeding the warnings to potentially avoid these problems dr. walensky is talking about. look, i'll remind you and all three of us talked about this so much last spring. i'll show this graphic. the united states, italy and france. and i show this graphic because i think when we first started to see what was happening in italy last spring, everyone thought, well, that's italy. that's not going to happen here, right? and then not only did it happen here, as you can see earlier, you know, last year, we surpassed italy. now it's a question of, okay, our cases are lower than they have been in a long time, still not low enough, but again, see what's happening in france and italy? things are starting to click up over there. shut downs and significant mandatory mitigation measures are going into effect there. i mean, it's like how many times do we have to learn this lesson? are we in a better position with the vaccines? yes. are they going to immediately slow down the spread of this virus? no. masks do that. physical distancing does that. all the things that we've been talking about. this is fundamentally just a small strand of genetic material. can't jump very far. doesn't like to be outside. and is fairly, easily contained by a mask. we know that now. if we can just sort of abide by those simple, i think, pretty simple mitigation measures for another few months we can quell this thing down to where we have it contained. we finally have it in a box. we've never had this thing in a box almost since it started spreading in this country more than a year ago. >> sanjay, what does that mean for schools? i know you have a new essay out this morning talking about your evolution, what you've been through with your own kids in school. >> yeah, look, i learned a lot about schools. i was very skeptical because, you know, i thought kids were going to be these super spreaders. i have kids just like you have kids. every time one of my kids came home with a cold, everyone was going to get it in the household at some point. i had no reason to believe it would be any different with this coronavirus. but what we are now seeing from schools is that in schools that have, again these same mitigation measures i mentioned, adequate masking, adequate square footage to physically distance and the doing things outdoors as much as possible, having good ventilation, it makes a difference. you can argue in many school districts the school is a safer haven with regard to viral transmission than the surrounding community. that the positivity rates are lower in schools. there's still a lot of schools that can't abide by those basic mitigation measures. i'm still shocked so many months into this that we still don't have testing. people have given up on this idea you could test and maybe we will still get to that point because $50 billion have been put aside for testing in this new relief plan. but you know, we've been flying blind. but despite that, schools have largely been safe havens. teachers are now increasingly vaccinated. i think schools are still probably going to be okay. >> maybe schools are the model for how we can do things, right? keep the mask on. keep that -- >> it is. >> imagine that. imagine that. sanjay, always good to see you, my friend. thank you. >> you got it. thank you. president biden bringing his message of help to pennsylvania today. as the administration begin assass assasss nationwide tour. part of an effort to combat a potential new wave of infections. cnn's jeremy diamond live at the white house this morning. jeremy, good morning. >> reporter: good morning, erica. listen, we're in this strange place in the country right now. we see these cases continuing to decline albeit much more slowly. millions of people getting vaccinated everyday but there's this threat of the coronavirus variants on the horizon. that is why sources have told me that the white house has been racing to prepare for and also try and prevent a fourth coronavirus surge in this country. they have been mapping out different scenarios of how this spread -- this surge might unfold in the united states working to prepare the publics and governors of a fourth coronavirus surge and drawing up plans for how they would respond. and one way that they would respond would be different than anything we've seen in previous coronavirus surges. that is that the white house, according to two senior administration officials have drawn up plans to surge vaccines and vaccine mobile clinics to emerging hot spots around the country to try to blunt the trajectory of potential coronavirus surge. so this would be using the federally-controlled pipeline of vaccines, sending extra shipments of vaccine doses to hot spots through retail pharmacies. or using those mobile clinics that are run or supported by fema. one senior administration official telling me that we have different tools than we did last year and we can't play yesterday's game with this virus. but so much of what this administration is doing to prepare for another surge is about communication. i spoke with dr. ann shukutt, the number two official at the cdc, at the cdc in that role in the trump administration as well and she said the more consistent messaging on the science and the reality of what is happening with this virus is what is helping to prepare the country of the prospect of another surge. this is a white house, of course, telling the public, warning in recent weeks, as the president did last week that things might change even though the national outlook looks much, much better now, things might change, restrictions might need to be reimposed, but they're racing to vaccinate as many americans as possible to try and prevent that surge from happening. erica? >> jeremy diamond with the latest for us. jeremy, thank you. the biden administration facing heat from both republicans and democrats now, announcing a new policy and new place to house thousands of migrant children. we're going to speak with the white house's top coordinator about the recent surge at the southern border. university of phoenix is awarding up to one million dollars in new scholarships through this month, because hope fuels opportunity. see what scholarship you qualify for at phoenix.edu ♪ ♪ we made usaa insurance for veterans like martin. when a hailstorm hit, he needed his insurance to get it done right, right away. usaa. what you're made of, we're made for. usaa usaa. what you're made of, we're made for. you know when your dog is itching for a treat. itching for an outing... or itching for some cuddle time. but you may not know when he's itching for help... licking for help... or rubbing for help. if your dog does these frequently. they may be signs of an allergic skin condition that needs treatment. don't wait. talk to your veterinarian and learn more at itchingforhelp.com. so you're a small business, or a big one. you were thriving, but then... oh. ah. okay. plan, pivot. how do you bounce back? you don't, you bounce forward, with serious and reliable internet. powered by the largest gig speed network in america. but is it secure? sure it's secure. and even if the power goes down, your connection doesn't. so how do i do this? you don't do this. we do this, together. bounce forward, with comcast business. developing this morning, more than 2,000 migrant teenage boys who crossed the u.s./mexico border alone will be sheltered in a dallas convention center starting this week. this is part of a white house plan to handle the surge in backlog at the southern border. cnn's rosa flores live in texas with much more. rosa, what have you seen? >> reporter: john, good morning. here is how the process is supposed to work. border patrol encounters unaccompanied children. those children are suppose to be processed 72 hours and transferred to hhs care. well, that is not happening fast enough. according to attorneys who represent these minor children, these attorneys say that some minors are spending five to seven days in the facility that you see behind me without being able to go outside, without being able to talk to their parents or family members in overcrowded and unsanitary conditions. >> reporter: as tens of thousands migrants make the dangerous journey to the u.s. southern border. someone stole all her money along the way. many discover that getting here is just the beginning. some migrants describe -- crowded immigration processing centers. she says it was packed with people. without showering facilities. did they let you shower? and some say they slept under a bridge overnight. on pebbles and sand while waiting to get transported to immigration processing facilities. once there, migrants say they get three meals a day. this as cnn learns about 4,200 unaccompanied migrant children are in border patrol custody, attorneys blowing the whistle this weekend about children in overcrowded and unsanitary conditions at this massive temporary immigration processing center in donna, texas, unaccompanied children, including many under 10 years old, are being held. some for five to seven days which is against u.s. law. peter shea representing thousands of unaccompanied minors in federal custody and says capacity at the donna facility is 1,000 detainees. right now it's holding about 2,000. >> it's untenable situation. the administration needs to address immediately. >> reporter: the head of homeland security directed fema to help credit more shelters for unaccompanied children and move them out of border patrol custody quickly. do everything they can do take care of unaccompanied children in their care. mothers entering with children, many are released at this bus station in brownsville. >> why did you come here? she said the economic crisis in her country is very severe. >> reporter: the reasons migrants say they're trekking to the united states varies. some, like this gentleman, says he lost everything during a recent hurricane in honduras. and this woman says the toughest part of her journey was when her daughter was hungry and she has no food she's here because of the lack of jobs and abundance of violence in her home country. now, in prior years, cnn has been granted access to immigration processing centers. sometimes even just pen and paper. this time my team and i have been here for a week and we have asked border patrol and custom and border patrol access to the facility you see behind me and other processing centers and that access has been denied. we also asked about the migrants say they've been sleeping under a bridge overnight, waiting to get transported to processing facilities and, john, we have not heard back. >> rosa, thank you for asking the questions. thank you for being there. joining me now is beard roberta jacobson. thank you for being with us. i know you were able to hear rosa's piece right there, and obviously there's a lot that we're not being allowed to see, but we did hear some stories about the conditions that people are being kept in. are these conditions good enough? >> well, i think it's very clear, john, that we want to make sure that children, unaccompanied minors, are taken care of appropriately. and that's why we're doing everything we can to make sure we have facilities that are appropriate for children so that they can be processed quickly and moved to sponsors, families, foster homes. that's what hhs does well, but we have numbers that require that we look for additional facilities. we've also done a number of things to make sure that this goes more smoothly, embedding hhs personnel with our colleagues, rescinding a trump era memorandum of agreement that made it harder for parents or families to come forward to claim these children. all of those things are helping. >> there has been criticism that these are things that should have been done before changing the policy about unaccompanied minors coming over the border. so why weren't they done before? >> well, i think it's important to understand that this administration has been in office six or seven weeks. we've moved swiftly to make sure that we restore humanity to our immigration policy. and in doing so, that obviously means we have to treat people and children especially well. we're moving really quickly, a request for information for additional facilities went out immediately. but it's important that we make sure children are moved out of border patrol stations, secretary mayor ka said it well. but we also have to look at the other end of this chain. the people in the story that were talked to, talked about the results of two hurricanes in 15 days. so that's why we're speeding feeding programs, economic programs to make sure that they can maintain their homes in their home countries. >> i think those are efforts that are widely agreed upon as being noble and productive in the long term. but in the short term, i'm talking weeks, weeks at this point, what is the administration doing to reduce the number of unaccompanied minors coming over the border? >> well, i think it's important to understand that we've been talking with the mexican, the guatemalan, the salvadoren governments since the day we came to office, working with them to make sure we're speeding humanitarian aid which is increasing. that's quick dispersing to make sure that we are working with them to slow down the flow especially during a period of covid. our relationship with the mexican government is very good. we have to work, as i say, at a