fighting in this war, alongside the ukrainians. how many other u.s. fighters are risking their lives in ukraine right now? our correspondents are standing by on the ground in ukraine with refugees in poland and with president biden over at the white house. we want to welcome our viewers here in the united states, and around the world. i'm wolf blitzer. you are in "the situation room." tonight, russia is making slow but alarming new progress in this, the tenth week, of its brutal war against ukraine. noish officials in kyiv, moscow, and here in washington -- they are now digging in for this bloody conflict potentially to last for years. cnn's anderson cooper is standing by in the ukrainian capital for us. kai kaitlan collins is over at the white house. we will go live to them in just moments. but first, there is growing concern about the fate of the last holdouts in the besieged city of mariupol as cnn's jim sciutto reports from the war zone. >> reporter: hundreds of civilians, including children, still trapped in a mariupol steel plant tonight, after russia blocked ukraine's latest attempt to rescue them. the last ukrainian military holdout in the embattled city and potentially ahead of another attempt to storm the plant. >> there is lack of everything, lack of water, food, lack of medicine, lack of any social help. so they need to be humanitarianly evacuated as soon as possible. >> reporter: mariupol's mayor now claims more than 600 people injured no total after a bombing that hit a makeshift-military hospital. inside the complex, military commander inside the plant spoke with cnn. >> translator: the situation is critical. it is beyond the humanitarian catastrophe. we cannot tell you for sure how long we can hold on for. that all depends onto enemy' movements and also on luck. >> reporter: humanitarian corridors for mariupol were one of the items u.n. secretary general antonio guterres lobbied for in his visits with presidents putin and zelenskyy this week. but while he was meeting with z zelenskyy thursday in kyiv, several russian missiles struck. the attack shattered the relative calm in the capital. one last killed a ukrainian journalist in her apartment. ukraine's foreign minister called it, quote, a heinous act of barbarism. russians are now making incremental progress in eastern ukraine. this video shows extensive shelling of an important railway line and supply line for ukrainian troops. a key railway bridge destroy as well. >> they are trying very hard to overcome the challenges they had in the north by making sure l logistics and sustainment can keep up but ukrainians are making it hard for them to make any progress. >> a fuel depot attacked overnight in the donetsk region, controlled by russian-backed forces. and ukrainian officials say a town in the northeast near kharkiv has been recaptured. jim sciutto, cnn, lviv, ukraine. >> jim sciutto, thank you very much. let's go live right now to kyiv still reeling from the first russian strikes on the city in weeks. cnn's anderson cooper is in the ukrainian capital for us. ar anderson, you are joining us now live. i know you interviewed the mayor of kyiv earlier today. what did he tell you about yesterday's strikes by the russians? and the continuing threat to the ukrainian capital? >> he was a little less diplomatic than the ukrainian official whose tweet you just showed there. he said that the strike that took place here in kyiv yesterday, while the secretary here, was essentially a middle finger by vladimir putin to to the not only the secretary general but to the international community and to ukraine. as you knowers as jim was reporting, one person was killed in that strike. as many as ten were -- were injured. it hit near an apartment complex. the first two stories of that bui building engulfed in flames. it took rescuers about an hour to -- to put out. but it is a reminder i think to everybody here in kyiv that the danger even though so-called phase two of russia's invasion is happening really in the east, the danger here in kyiv, and really anywhere in ukraine remains, wolf. >> certainly does. anderson, i know you had a chance to finally meet, face to face, with a mother who has been speaking to you throughout all of this conflict. she is in a basement. she's been sheltering there. what was that like? >> yeah. her name is alana. she is a mom of three. her husband joined territorial defenses here in kyiv. and she has been trying to take care of her kids. she has been, pretty much every night, in a basement shelter. even now that kyiv is not under direct attack as freakily as it was before, she still goes to the shelter every night but we visited her in her apartment, where she spends the days, and then goes to the shelter at night. here is some of what she told me a about she and her kids have been through over this -- this last two months. >> the first weeks, i put many phone numbers on their bodies. like, i -- i -- i put my phone number, my husband's phone number, my sister's phone number. >> reporter: you would actually draw it on their skin? >> i just wrote this on the bodies, on the hands, from the hands. like okay, if i die, okay, if sergei die, another phone number of my sister, of my sister and kids so el okay, i will put their grandmother. she will survive. >> you had to think about that? >> i -- and this is what many no mothers did here. >> do you feel safe now? >> no, i don't. of course, i am not like crying all the time anymore. i -- i can sleep right now at night. i can eat food, which i couldn't in the beginning but i do not feel safe right now because the sky is not closed. and this air attack can happen at any time, in any place of ukraine so there is nowhere safe in ukraine. >> nowhere safe here. and as you know, wolf, people are being encouraged to limit the use of cars to save on gasoline to make sure there is enough gasoline for the military whenever they need it, wolf. >> anderson cooper in kyiv for us. anderson, stay safe. we will be in touch. thank you very, very much. another heartbreaking story, indeed. let's go to the white house now, before top officials are bracing for the possibility of a face-to-face showdown between president biden and vladimir putin. our chief white house correspondent kaitlan collins joining us right now. d the up am canning g20 summit in indonesia, what are you learning? >> it is raising so many questions for the white house, wolf, because it puts them in the position of what do they do? now that putin today has accepted this invitation to go to the massive summit with other world leaders, hosted in indonesia, by indonesia. so of course, they are still extending that invitation and have not rescinded it despite that ongoing invasion of ukraine. and president biden has side ehe wants putin and russia kicked out of the g20. he said he will still attend, though, if ukraine is invited and goes. it is not clear whether ukraine will actually attend the summit but it raises so many questions fort president and his team about what do they do, given the possibility, of course, in just a few months from now if putin and president biden being in the same room together. and so, they say they have not made a decision on that yet. they say it is still six months out before they have to make a decision about whether or not president biden is actually going to attend or whether or not he boycotts the g20 summit. though, we should note, wolf, we have been talking about this request for congress to aid ukraine, to fund them and give them more weapons for the next five months but gives you an indication how long the white house does expect this invasion, this war in ukraine to continue going on. we should also this comes as the pentagon is getting more and more blunt by the day in how they are talking about putin and what he is doing in ukraine. >> it's difficult to look at the -- sorry -- it's difficult to look at some of the images, and imagine that any well-thinking, serious, mature leader would do that. so i can't talk to his psychology but i think we can all speak to his depravity. >> those will strong words, wolf, from john kirby who you know very well does not get very emotional from talking like that. did today. he later apologized for the emotion in his voice. it echoes what so many feel about what is happening in ukraine and that is why it makes questions about whether or not biden is going to go to this g20 summit that putin says today he will attend in november makes them just that important, wolf. >> i have known him for a long time. he certainly does not need to apologize for showing some emotion. it is so, so heartbreaking just to see -- see these stories unfold. thanks very much, kaitlan, for that report. just ahead. a former-u.s. marine becomes the first-known american to die fighting in this war in ukraine. stand by. we have got new information for you. 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(crowd applauding) therabreath, it's a better mouthwash. at walmart, target and other fine stores. breaking news tonight. president biden just speaking out moments ago about the first-known death of an american fighting in this war in ukraine. the president saying -- and i am quoting him now -- it's very sad, he left a little baby behind. cnn's brian todd is working the story for us. brian, his name is willy cancel. he is a former-u.s. marine. what other information are you learning about him? >> his mother spoke to cnn and said he was killed monday. we have new details tonight on the circumstances surrounding this young man's deployment to ukraine, some of which are still a mystery. >> reporter: he is a 22-year-old american, and leaves behind a wife and 7-month-old baby. former-u.s. marine willy joseph cancel killed on the battlefield in ukraine. that is according to cancel's mother, who spoke to cnn. neither, cancel's mother, nor u.s. officials, could provide information on how or where cancel was killed. >> we know a family is mourning. a wife is mourning. you rememb and our hearts are with them. >> cancel's mother tells cnn he was working as a corrections officer in tennessee when he signed up to work for a private military contracting company. when the conflict began, she says, cancel agreed to go. he flew to poland on march 12th, and crossed into ukraine shortly thereafter. she says he was being paid while he was fighting there. >> that is a horse of a different color than his being directly in some kind of ukrainian-foreign legion. and that begs the question, who is the client of this private contracting company? is it for the government of ukraine? >> reporter: no immediate answers to those questions tonight. and u.s. officials say they don't have an exact count of how many americans are fighting in ukraine. a ukrainian defense official told cnn in early march that at that time, more than 20,000 people from more than 50 countries had ex-preksed a desire to join the fight. cnn has interviewed some americans who volunteered. former-tv analyst, malcolm nance, described fighting in a special ukrainian unit called the international legion. >> it is not just people running around, grabbing rifles, and going on the battlefield. it is a unified force, that is a component of the ukrainian army that is deployed on the battle front. >> reporter: but another american fighting there, james vasquez, told cnn he was moving around loosely. >> right now, i am pretty much a ghost. me and a british soldier have been going unit to unit, wherever we are snided the most. >> tonight, u.s. officials are again warning americans don't go to ukraine to fight. >> this is an active-war zone. this is not the place to -- to be traveling to. >> reporter: state-department officials say russian forces could single out americans fighting in ukraine. one official warning that captured americans could be subject to, quote, heightened risk of mistreatment. >> it is not hard to imagine a situation, in which a captured american is tortured, is executed on the battlefield, or is just sent back to moscow to be some type of pawn for political exchange. >> reporter: at the time she spoke to cnn willy cancel's mother said the people who notified her of his death said her body had not yet been found. she said the men who were with him were trying to recover cancel's body but that it was simply too dangerous. wolf. >> brian todd reporting for us. brian, thank you very, very much. and joining us now, the state department counselor, derek, thanks so much for joining us. i just want to get your reaction to the death of this 22-year-old american, a former-u.s. marine, bh who was fighting in ukraine against the russians. what is your reaction to that? >> well, this is very tragic, it is a terrible loss of life. this is a war. it is a very dangerous place. understand the all trustic moments of this person who went to fight in ukraine but this is something americans should not be doing. american citizens should not be going to ukraine. it is very dangerous. there are other ways that americans can contribute to this effort but our -- our thoughts are very much with his family and his friends and we are standing by to assist in any way possible here at the state department. >> yeah. and i mean, he obviously wanted to do good. but sadly, he got killed in of the process. >> right. >> president biden, as you know, rejects the idea that ukraine has become what is called a proxy war between the u.s. and russia but could putin seize on americans fighting in ukraine to make that case? >> bi think putin is going to seize on any pretext he can to try to justify any unjustifiable on his brutal invasion. we, the united states government, will do whatever we can to support the ukraine in people and support the government of ukraine. that's why president biden, just yesterday, asked congress for another $30 billion in assistance for ukraine. 20 billion of that will be for security and defense needs so we are standing by, and prepared to do whatever we can to support ukraine and i think the american people, also, are standing up and supporting ukraine, ukrainian refugees, and also ukrainian' humanitarian needs that are profound at this moment. >> certainly are. it is heartbreaking to see what is going on over there. >> absolutely. >> putin, as you know, derek, has now accepted a formal invitation to attend the g20 summit in bali, indonesia in december. can president biden participate in the g20 when he is called for russia to be ousted from the g20 altogether? >> well, wolf, as you said, president biden made very clear several weeks ago that he believes it cannot be business as usual with russia, and vladimir putin should not be able to attend the g20. now, this is not the united states' call to make alone and he said if president putin were to attend the g20, that president zelenskyy should also have the opportunity to attend as well. this is some ways off. but president biden remains clear it should not be business as usual with russia given the brutality every day they are constructing ukraine. >> we know they have invited president zelenskyy as well to attend. if president zelenskyy goes, do you think the president of the united states should attend? >> all i can say, wolf, is the president himself said which he believes putin shouldn't be able to attend. if he were to attend, indo-neegdss as the hosts can decide this. that president zelenskyy of ukraine should be able to go. again, this is a summit in november so it is a ways off so we got a lot of time, between now and then. >> nato has been forced in recent days to scramble fighter jets multiple times, in fact just the past four days alone, to intercept russian' aircraft flying near nato airspace. the longer this war goes on, derek, is there a risk -- the risk growing of a direct u.s.-russia confrontation? >> well, wolf, this is war and there are many, many risks involved. russia is pushing the envelope every day, and we have seen errant missiles flying around, missing their targets in ukraine, hitting civilian areas in ukraine. and nato has been very clear, very steadfast about this, and the united has been very clear and steadfast that we will defend every inch of nato' territory. president biden has been clear from the outset that we will do so. the united has flown a significant amount of force into the eastern flank of nato to help support and bolster nato. about 100,000 u.s. troops there now. there is ap important nato summit coming up in june in madrid which i think will be another demonstration of solidarity and unity and again, we will defend every inch of nato territory. >> thanks wolf for having me. appreciate it. >> appreciate it very much. coming up. forensic experts are heading to ukraine as part of an investigation into alleged-war crime. i will speak, live, with the chief prosecutor of the international criminal court. that's next. you get up to 10 timeses the spd at no extra cost. verizon is going ultra, so your businessss can get more. when my genetic reports told me about my heart health, i was able to take action. and i got a kit for my mom, too, so she can get her own meaningful health info. this mother's day, start a new health journey together with mom with $50 off every kit. people with plaque psoriasis, are rethinking the choices they make. like the shot they take. the memories they create. or the spin they initiate. otezla. it's a choice you can make. otezla is not a cream. it's a pill that treats plaque psoriasis differently. with otezla, you can achieve clearer skin. don't use if you're allergic to otezla. otezla can cause serious allergic reactions. it may cause severe diarrhea, nausea, or vomiting. otezla is associated with an increased risk of depression. tell your doctor if you have a history of depression or suicidal thoughts or if these feelings develop. some people taking otezla reported weight loss. your doctor should monitor your weight and may stop treatment. upper respiratory tract infection and headache may occur. tell your doctor about your medicines and if you're pregnant or planning to be. otezla. show more of you. can a company make the planet a better place? at walmart, we're pursuing 100% renewable energy in our operations. and aiming to protect millions of acres of land. so we can all live better. everyone knows eating well and exercise are a big part of losing weight. ww's new program teaches you how to do it. i still eat the foods i want to eat and i have lost 69 pounds, james. you're just changing your mindset and shifting your eating habits. for me ww is all about flexibility. there's no restrictions. more knowing means more doing. do with ww. i'm reading your aura right now. it's telling me that ww works. get you first 3 months free today at ww.com offer ends may 2nd. this hour, we are getting new accounts of the damages, the injuries, the anger in kyiv after russia attacked the capital city of ukraine during the u.n. secretary general's visit there earlier-this week. the kyiv mayor, likening the attack to russia giving ukraine the middle finger. survivors of the new missile strikes are also sharing their personal stories. here is cnn's matt rivers in kyiv. >> reporter: it had been weeks of relative quiet in kyiv but a couple bangs and a plume of black smoke quickly changed that. cruise missiles were fired into a central district of kyiv miles away from where the u.n. secretary general had just wrap pd up a meeting with president zelenskyy. rescuers worked through the night, zbht morning, a clearer picture emerged about what happened. with this apartment complex shredded by shrapnel, leaving those in the neighborhood shaken. this wall saved my life, she says. otherwise, it would have been the end. there was a lot of fire. i could siee everything was burning. i was so scared, it was horror. she said she only survived because she wasn't sitting next to the window. her son, alexei's hands bloodied. he says a clap, a blast, then panic. that's it. i didn't see it, until later, i saw my hand was kocovered in blood. mother and son survived, while others affected by the strike did not. a 54-year-old ukrainian journalist lived here. having just returned to her home about a week ago. no one ha h heard from her all night, so friends kept trying to call her. her ringing-cell phone led rescuers to her body this morning. i i have no words, says this friend, no tears left, i have no energy to cry. only a few days ago, she was asking how she could help me because my house burned down. and now, no one can help her. russia's ministry of defense says they were aiming for a factory right nearby here that is one of ukraine's top producers of air-to-air guided missiles, as well as aircraft parts. we can't show you that factory due to ukrainian' law. the factory was damaged in the strike but so was the apartment complex just behind it. yet another example of russia targeting places with supposed military ordinance but killing civilians in the process. >> the victim of an attack president zelenskyy says proves, quote, one cannot relax yet. one cannot think the war is over. we still need to fight. >> and, wolf, president zelenskyy acknowledging-let death of that journalist saying she is the 23rd member of the media that has been killed during this war. meanwhile, as people continue to come back here to kyiv -- and those numbers have increased the past several weeks, despite ukrainian authorities saying it is not quite safe enough to return, you have to wonder if these missile strikes will give people pause as they wonder whether to return home to kyiv after fleeing in the earlier part of the war. wolf. >> matt rivers, reporting from kyiv. stay safe there, matt. thank you very much. o. outside of kyiv in bucha, investigators are gathering evidence of potential russian' war crimes. a ukrainian prosecutor shared these graphic and very disturbing photos with cnn taken in mass killings in bucha earlier this year. multiple organizations are looking into atrocities in ukraine. joining us now, the chief prosecutor of the international criminal report karim khan. i know you have been meeting with top officials in the united states, as well as united nations. sharing information you have gathered in ukraine and bucha and elsewhere. but your message is to russia, i understand, have gone completely unanswered. what would you say to putin, as these atrocities clearly mount? >> well, what i will say to all sides is that there are basic principles of law that are not optional. that all sides, all parties to a conflict must comply with. and the cost of not compliance, of course, are human casualties, destruction of property, massive insecurity. but also, there is a criminal jurisdiction involved, namely international criminal court and i am open to speaking to all parties but there are these basic parameters of conduct we have to adhere to. >> i am told, karim, you will be deploying some 30 some experts to ukraine. what is their mission? >> 30 forensic scientists, crime-scene experts, technological experts, and others, and they have been -- in fact, been provided by -- to my office -- by the kingdom of the netherlands. so, it is this partnership that we are building trying to use resources of course the various systems of the course -- court and gather evidence because as i said, previously, ukraine is a crime scene, and we can't establish it by -- by interviews or by utterances. we need real evidence. ballistics, evidence, testimonial, electronic evidence, satellite evidence, and other evidence that can be obtained on the -- on the battlefield and soon thereafter. so we want to collect it, analyze it, and see what actually is shown and if there are crimes committed within the court's jurisdiction to find out who is responsible. and then, present that ievidenc to independent judges for determination. >> you just said ukraine a crime scene right now but how do you try to investigate potential war crimes, karim, in places like mariupol, for example, where there is essentially zero access? >> absolutely right but still with satellite evidence and other evidence, even some of the pictures that coming r coming in, um, from the ground. evidence may be preserved and what is being received can be, again, subject to evidential scrutiny for authenticity and the like. but there are places we can access. i have been, twice, already to ukraine, to kyiv, to lviv. i have been to bucha. borodianka. the forensic experts and my team on the previous missions have been to other locations. so everything is interconnected. it is about breaking it down, seeing what happened, why it happened, and -- and who is responsible. and we will get to other areas, i am sure, in due course. but the basic principle has to be, wolf, that -- um, you know, there is basic norms that have be complied with. that is the important point. it is not about east and west. it is about, do we value, collectively, these -- the rights of women and children not to live in terror? um, for civilian objects not to be targeted? and if we don't, um, things are going to get worse and i think, um -- for me at least and i think for the office, is more relevant now than ever. and that's been evidenced by the really significant support within 48 hours of my invitation to states to refer the matter to court, we had 39 states. we have 43, total, now. 43 states all parts of the world, asia, like japan, chile, costa rica, colombia, have referred to the court, as well as most european countries and i think now, more than ever, we need to cling onto the law to make sure that these basic principles are not viewed as the preserve of lawyers in our gowns in the hague or your judges but they are the common heritage of mankind, and are valuable and meaningful to the people who we see on -- on the streets. women, whose apartments have been bombed. offer or children that are shivering in subways, refugees, care veins of humanity going to poland and other locations uncertain what tomorrow will bring. if we can make it relevant now, hopefully can maitigate the wort horrors to approximate done. and look for accountability so the right to life and the right for human dignity are not confined to council chambers in new york or to courts in the hague. but actually, rendered evermore effective and that must be the aim. >> certainly must be. karim khan, thanks so much for joining us. karim is the chief prosecutor of the international criminal court working on the alleged war crimes being commit by the russians right now in ukraine. staying with cnn later tonight for a close look at a behind-the-scenes situation unfolding in russia. the cnn film "navalny" takes viewers inside the investigation into the brazen assassination attempt against the russian-opposition leader, alexei navalny. that is tonight 9:00 p.m. eastern, only here on cnn. just ahead. the aelty of life as a refugee, that millions of ukrainians are now facing in poland. plus, covid vaccines for young children could be just a few weeks away. we have got new information. we are getting details from moderna's chief medical officer who is standing by, live. we will be right back. wrwrap their arms around us, could we put little handles onon our jackets? 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>> translator: yes, i left with my family. but to fight? i don't know. tsa difficult question for me. i can't answer. >> there is so much that can't be answered, including how long this will last. the need is massive. there are vo lull teens working in this space 24/7 to deal with all the donations but if needed, they could push all this back to koom accommodate more beds and as many as 6,000 lef refugees but officials say there is no bay to know what the numbers will be from one day to the next. olive fled with her mother request two young daughters at the start of the war. now, she is one of several psychologists volunteering to help those who just arrived. increasingly, they are from the hardest-hit areas. >> translator: there are no easy stories here. either, you spent a month in the basement or ran from shelling, or don't know when you can go back. you don't have anything here. >> reporter: making simple moments all the more important. the goal is to make this space as comfortable as possible. yet, the truth is no matter how warm or welcoming, no one wants to be here. they'd rather be back home. the reality is no one knows, wolf, how long the shelter will be needed but just to give you a further sense of the scale of this operation. you say the washing machines that were brought in. showers were brought in, as well, six tons of toilet pipe paper and half a million cough key cups, wolf. >> amazing what the polish people are doing and receiving. please say thank you to them on behalf of all our viewers. we are all grateful. thanks very much. erica hill reporting from warsaw. coming up, covid vaccines for the youngest americans could get a green light in a matter of only a few weeks from now. we are going to talk about it with the chief medical officer of vaccine maker, moderna, when we come baback. for a limited time, get 50% off a complelete pair. visionworks. see the difference. ♪ ♪ we believe there's an innovator in all ofs. ♪ that's why we build technology that makes it possible for every business... and every person... to come to the table and do more incredible things. when my genetic reports told me about my heart health, i was able to take action. and i got a kit for my mom, too, so she can get her own meaningful health info. this mother's day, start a new health journey together with mom with $50 off every kit. ♪ (drum roll) ♪ ♪ (energetic music) ♪ ♪ ♪ ♪ ♪ (camera shutters) the all-new lx 600. ready for any arena. ♪ ♪ (driver) conventional thinking would say verizon has the largest and fastest 5g network. but, they don't. they only cover select cities with 5g. so, for me and the hundreds of drivers in my fleet, staying connected, cutting downtime, and delivering on time depends on t-mobile 5g. and with coverage of over 96% of interstate highway miles, they've got us covered. 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(music) who said you have to starve yourself to lose weight? who said you can't do dinner? who said only this is good? and this is bad? i'm doing it my way. meet plenity. an fda -cleared clinically proven weight management aid for adults with a bmi of 25-40 when combined with diet and exercise. plenity is not a drug - it's made from naturally derived building blocks and helps you feel fuller and eat less. it is a prescription only treatment and is not for pregnant women or people allergic to its ingredients. talk to your doctor or visit myplenity.com to learn more. american children under age 5 could be eligible for covid-19 vaccinations as soon as june. the fda announced today that its advisers are scheduled to meet to discuss updates to the emergency-use authorizations of both the moderna and pfizer vaccines. let's get some more now from moderna's chief-medical officer, dr. paul burton, who is joining us live. dr. burton, thank you so much for joining us. as you know, there -- there was some worry regulators would wait until they could give -- give the green light to, both, moderna and pfizer, basically at the same time. has moderna been given any assurances that the authorization that you are seeking won't be postponed? >> so good evening, wolf, thanks for having me. look, um, we have heard the comments from dr. marks this week. there is clearly unmet need here, public health need. the fda will do a very thorough review as they always do and move quickly, so i am confident that that he will -- they'll move fast here. >> so, for the parents who have been waiting for this news, how well will this new vaccine that you are seeking emergency-use authorization for protect these kids? and what are the side effects, potentially, that parents should be aware of? >> yeah. so, wolf, when we looked at safety in this study, it was very reassuring and the effect of safety events in this age group, were common side effects but rates of high fever over 104 degrees only seen in 2% of the kids here, typically we see rates of 1% for other vaccines and in effectiveness we looked at antibody levels and wanted to see if we could get antibody levels in these kids to the levels we see in 18 to 24-year-olds and that's exactly what we found so when you take all the data together, w0olf, it's such a positive result. >> we're told the moderna vaccine is 51% effective among kids six month to see two years old but only 37% effective among kids two to five. what do you say to parents who see those numbers and wonder if it's still worth it to get their kids this vaccine? >> yes, absolutely, look, it's a great question. so what we found is vaccine effectiveness against symptomatic covid was as you say, about 50%. first of all, that means that this vaccine will half your child's risk of getting symptomatic covid when we look at vaccine effectiveness which came out in adults in the united states today that comes out every week, at the same time point about 10 weeks after the second dose, against omicron, we see vaccine effectiveness of about 50% for symptomatic disease so exactly what we saw in this study. but what we also see, wolf, is vaccine effectiveness against hospitalization but between 85 to 95%, so the number of 50% vaccine effectiveness against symptomatic disease because we're up against omicron but we still see 85 to 95% protection because of that excellent antibody level for hospitalization so that's very reassuring. >> we know you're proposing a two dose moderna vaccine regiment but suspect ultimately, kids will have to get another booster. >> i think the natural history with this virus throughout the pandemic has been the additional doses will need to keep antibodies up so i would predict we will need something either in the winter of this year or even early next year, even from these youngest kids and we're certainly studying that as well now. >> dr. paul burton thank you so much for joining us, good luck with the new vaccine, for kids, we know a lot of parents are anxious to get their kids vaccinated. up next, newly revealed text messages now show fox's sean hannity advising the trump white house in seeking direction. we have a cnn exclusive report when we come back. our unique water baseded formula and 6x more glycerin. helps restore skin to its best condition. new dove ultimate. 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"outfront" next, breaking news on multiple fronts, putin's forces making key gains tonight, tensions high in the steel plant under siege with thousands of people inside and the mother, the first american known to be kill fighting in ukraine speaks out moments ago to cnn, plus he risked his own life to save nel oh ukrainians, turning his night club into a bomb shelter and tonight he'll talk to us. and shanghai's extreme covid lock down turning into a witch hunt, neighbors turning against each other, ou