pig to human heart transplant. and dramatic body cam. officers pulling a pilot out of a crashed plane seconds before it's hit by a train. this is nbc "nightly news" with lester holt. good evening the numbers remain staggering tonight, stretching our patience and our capacity to fix all that covid has broken. from the millions forced to isolate at home to the emergency rooms and icus desperately short on staff but filled with the sick, including the very young we've learned that over the last week more than 580,000 child covid cases were reported, tripling the number of cases two weeks prior. the weekly average number of new covid cases overall is close to 700,000 the good news is the number of deaths has been stable, but the strain and stress on our hospital remains critical as more breakthrough infections happen with timely testing remaining a problem. also tonight an update on an omicron-fighting vaccine that's in the works. first miguel almaguer with late details. >> reporter: tonight a new vaccine that specifically targets omicron may be just months away. but as new covid cases explode, our nation is likely just weeks from reaching omicron's devastating peak, with nearly every state now a hot spot, the u.s. is closing in on 700,000 new cases a day, nearly triple last year's surge. pfizer's new vaccine would target omicron and other variants already circulating. >> this vaccine will be ready in march. i don't know if we will need it i don't know how it will be usedit will be ready. >> reporter: in recent weeks, infections have some five and a half million cases just this month while most infections are mild and don't require hospitalization, in areas first hard hit by omicron, there is now a dramatic fight in covid-related fatalities. >> there has been more deaths that i have seen the whole time in just one week than i normally see in a month, let alone in a day. >> reporter: first detected in the u.s. six weeks ago, omicron is decimating the workforce and quickly spreading among children in two weeks, cases nearly tripling with well over half a million kids infected in the first week of january. it comes amid a serious shortage of hospital staff >> we have hundreds of doctors and nurses now that have covid and are isolating because of that. there are many hospitals in the country that are simply on their knees. they are overwhelmed. >> reporter: as the cdc sets the stage for a fourth shot for the immunocompromised, demand for testing remains high lines snaking for whiles through some residential neighborhoods. los angeles county just shattered a pandemic record. 45,000 new cases in a single day many of the sick are vaccinated, even boosted. >> you get vaccinated. you get boosted so that you don't end up in the hospital. you don't end up on a ventilator and you don't die from covid. >> miguel, if i could circle back to this testing issue. tonight the white house says americans with insurance won't need to pay for at home testing kits. what else did we learn? >> reporter: well, that's right, lester hoping to expand testing, the white house says americans with private health care insurance won't need to pay for those over the counter at home covid test kits consumers will instead be able to have their health care plan cover the cost upfront or be reimbursed that policy goes into effect in five days. lester >> miguel almaguer, thank you. as ukrainian troops dig defensive positions tonight in anticipation of a possible russian invasion, u.s. officials are digging in, too, holding the first of high stakes talks with their russian counter parts in an urgent mission to avert open conflict in a moment, some of my interview with the white house national security adviser, jake sullivan but first to the front lines where we start with richard engel. >> reporter: you can see how confident ukrainians are in diplomacy with russia, with every scrape and swing of their shovel. today troops are digging new defensive trenches in the frozen ground close to russian forces ukrainian troops are preparing for the worst because they worry that russia is not negotiating in good faith and is just going through the motions of diplomacy so it can say it gave peace a chance and then invade anyway senior american and russian diplomats met for nearly eight hours. no breakthroughs though russia's lead diplomat today insisted it has no plans to invade, he added a warning. >> after every mistake, every miscalculation with respect to what should be done in your atlantics, security of countries, to the west of russia suffers. >> reporter: russia has more than 100,000 troops positioned near ukraine's borders. it is demanding ukraine never be allowed to join nato and that nato shrink back to what it was in 1997 dismantling much of the alliances present across eastern europe and the baltics. u.s. officials say it's such an unrealistic demand they worry vladimir putin is building a case for the talks to fail, creating a pretext to invade ukraine. at the front, soldiers told us they'll stand their ground as long as they can. olefski says, we all want to return to our families, but this is our land and we'll defend it. troops here told us they hope putin is bluffing, but they're not counting on diplomacy, suspecting it may be just a trick. the only good news out of today's deadlock is that the u.s., russia and nato have all agreed to keep talking, with more negotiations later this week. lester >> richard engel, thank you. for more on how the u.s. is viewing this tense standoff, i spoke late today with jake sullivan, president biden's national security adviser. mr. sullivan, thank you for joining us russia's opening message today was essentially we have no interest in invading ukraine. do you believe them? >> we believe the russians have positioned tens of thousands of troops and advanced military equipment on the border with ukraine and that they have done so with at least the capability, if not the intention to invade we believe the threat of invasion is real and we are determined through a combination of deterrence and diplomacy to divert that circumstance, to defend ukrainian integrity and sovereignty. >> the u.s. position is that some things are on the table, including limiting the size and scope of military exercises as long as russia reciprocates will that be enough, however? will the u.s. have to give more concrete concessions or incentives to make this process move to a peaceful resolution? >> the united states and our allies have been clear that there is a lot to talk about when it comes to reciprocal interest-based security parameters in europe we can talk about missiles and missile placements as we have historically with intermediate nuclear capable missiles we can talk about the size and scope of exercises. we can talk about greater transparency and risk reduction measures to reduce the possibility of unintended conflict. it is ultimately going to be up to the russians to determine whether they want to engage seriously on a substantive agenda or whether diplomacy is a pretext for them to take military action. >> what is the trip wire the white house trip wire to begin these very severe sanctions that have been proposed. >> if russia chooses to roll across the ukrainian frontier and further invade ukraine beyond the incursions it has already made, the united states will respond. we will respond with our allies we will respond with severe actions. >> our thanks to national security adviser jake sullivan. here in new york tonight, doctors are trying to save the lives of people critically injured in that devastating apartment fire, one of the deadliest in recent memory. there are new questions about how the smoke spread here's gabe gutierrez. >> reporter: tonight new images of the charred apartment where the deadly fire started. all that's left after the inferno tore through this bronx high rise sunday. >> this is an unspeakable tragedy. >> reporter: authorities today lowered the death toll from 19 to 17, including 8 children in the chaos with dozens of injured rushed to 7 hospitals, some of the victims were double counted. several are still in critical condition. >> the smoke the children >> reporter: jacobs lived on the 15th floor. >> i drop on my knees and start to pray. god please help us help us. >> reporter: authorities say the five-alarm fire was sparked by a space heater, and the door to that unit somehow did not close. the damage inside now seen in the new images published by dailymail.com. >> the smoke traveled thhe building. >> reporter: a ays that all doors on the building are self-closing to help contain smoke and that apartment was last checked in july. >> how much smoke was there? >> oh, my god. you can't imagine. a lot of smoke. >> reporter: the building's owner also says the smoke alarms did work, but residents would sometimes smoke in the stairwells which would set them off this survivor told us they went off so often, the residents would ignore them. >> that happened the consumer product safety commission estimated portable heaters are involved in about 1,700 fires per year, resulting in about 80 deaths. >> this tragedy is not going to define us it is going to show our resiliency. >> reporter: the fire commissioner says it was the smoke, not the flames that proved deadly here and that usually in a fireproof high-rise building, it is safer to stay in your apartment than to try and get down the stairs. lester >> gabe gutierrez, thank you. there are new details tonight about the sudden death of actor and comedian bob saget who was loved by millions for his roles on "full house" and "america's funniest home videos. here's joe fryer. >> reporter: for his role on "full house," bob saget won a title as prestigious as any award. >> okay. everyone's sandwich just the way they want them. >> reporter: america's tv dad, dispensing all kinds of fatherly wisdom. >> you girls are the greatest. >> reporter: now it is his tv daughters who are offering praise. bob was the most loving, compassionate and generous man say ashley and mary kate olson. one of the best human beings i have ever known tweeted candace cameron bure and from his on screen brother-in-law john stamos, i will never ever have another friend like him. >> he always lifted me up. just thinking about him now makes me happy. >> reporter: saget was found dead sunday inside an orlando hotel room according to the incident report, his family could not get a hold of him, so hotel security went to check and found saget on the bed with no pulse. authorities say they found no signs of foul play or drug use the medical examiner performed an autopsy this morning and will now determine how the 65-year-old died he was on a standup comedy tour. just hours earlier posted on instagram i guess i'm finding my new voice and loving every moment of it >> let's talk about strategy let's forget about strategy. >> reporter: saget rose to stardom in the '80s and '90s playing danny tanner on "full house," along with a gig hosting america's funniest home videos. >> look at all these wonderful moments. oh, is this fun. >> reporter: on tv his image was squeaky clean. >> there is a horse in my living room >> reporter: quite the contrast to his profanity-laced standup routines. >> i always had comedy that was both family comedy, whether it be a role i played or my standup, i was a little more unleashed. >> reporter: recently he reprised his role as danny tanner on the netflix series "fuller house. he leaves behind a wife and like his character had three daughters. the grieving family now asking fans to remember the love and laughter bob saget brought to the world. joe fryer, nbc news. convicted killer robert durst has died. the wealthy new york real estate heir was serving a life sentence after he was convicted in september of murdering his long-time friend susan berman durst was also suspected of killing his wife kathleen who vanished in 1982 and a neighbor who was shot at durst's apartment in 2001. robert durst was 78. coming up, the dangerous cold wave gripping much of the country. al roker tells us where and for how long and the u.s. figure skating dream team now heading to beijing. an arctic blast is bringing the coldest temperatures in years to parts of the country. al roker is tracking it. what are you watching, my friend? >> well, we are watching this big arctic blast that's coming down. it is sub freezing temperatures the jet stream has dipped down to the south. and, so, these are the coldest temperatures we have seen in three years in parts of the northeast. and, in fact, overnight lows windchills of 2 in pittsburgh, minus 1 in new york city, 10 in d.c., minus 9 in chicago. the good news is this is very short lived. by the end of this week, we will see temperatures moderating a bit 41 in new york city. 46 in washington, d.c. 36 in chicago. we have also got windchills to talk about and lake effect snow this is a big band of lake effect snow coming across. it's going to bring some areas another 5 to 8 inches of snow on top of what's already fallen, lester we're talking two inches of snow per hour between watertown and syracuse >> looks like winter's greatest hits. all right, al. thanks very much. we've got an incredible medical breakthrough to talk to you about this evening. the first ever pig to human heart transplant surgeons at the university of maryland medical center in baltimore announcing they placed a heart from a genetically modified pig into a 57-year-old man on friday the patient is said to be doing well. just 25 days until the winter olympics, opening ceremony and team usa has finalized its lineup in one of the most watched sports here's stephanie gosk with that. >> reporter: ladies and gentlemen, your 2022 u.s. olympic figure skating team. >> it's a really cool opportunity to get to show the world, you know, what you love to do. >> reporter: they will jump they will twist. and they will most certainly dazzle. >> when it comes to competition, it is like, hey, just go for it, you know >> reporter: nathan chen took flight to elton john's "rocket man" winning the national championship. recapping a nearly flawless stretch of skating since pyeongchang. on the women's side, 16-year-old alysa liu had to pull out because of a positive covid test, but she was still named part of the olympics team. >> it's seriously a dream come true and i'm so happy. >> reporter: winning nationals this year, 25-year-old mariah bell, making her the oldest u.s. champion in 95 years. >> something i have waited for for a really long time, and it's really amazing. >> reporter: covid has been tough on these athletes at one point vincent zhou had to skate on a makeshift rift >> somebody had one in their backyard with a sheet of ice on it >> reporter: and the virus is likely to be a challenge in beijing. but for now they're just happy to have their tickets punched. >> it is our time to shine and just have them do it is thrilling. stephanie go news. up can you see my wall of smiles? when i first started using genesys technology i was kind of embarrased at all the love and attention i got from my customers. people are so moved by how much i understand about them. they start including me in their lives. that's helen and her friends. i arranged a wellness retreat for them. look at those ladies. such wisdom. mmm. but it's really genesys that helps me understand people and what they truly need. i'm just glad i can help. as this country struggles to contain the latest covid explosion, we take a look tonight at the extreme measures china is taking in some cities, just over three weeks before the beijing olympics janis mackey frayer is there. >> reporter: tonight all 14 million people in tianjin being tested for the coronavirus. the city in partial lockdown after the first local cases of the omicron variant were found here. 75,000 people quarantined. the worry is that it will get worse. >> because of the transmissibility of it so, yeah, i do think people are alarmed and anxious, all hoping for that negative test result. >> reporter: the cluster in tianjin is small compared to most cities in the world, but it's only 70 miles from beijing, which is now on high alert with less than a month before the winter olympics with covid concerns running high here, olympic venues and all areas around them have been completely sealed off. it is china's biggest covid crisis since the first outbreak in wuhan. in the city of tianjin, millions are confined to their homes because of 1,900 cases. they are locked down and pleading online for help some unable to access medical care, including a pregnant woman who had a miscarriage outside a hospital because she didn't have a covid test to get in, igniting anger on social media here about the human cost of china's zero tolerance policy. >> in the coming months, it will be crucial, you know, for china in terms of the effectiveness of this strategy. >> reporter: for beijing's olympics, thousands of athletes and officials will go directly into a tightly enforced bubble. >> if they can pull it off, it will be an amazing olympics. >> reporter: but with the variant already spreading quickly in other countries, there is a race here to contain it before the games begin. janis mackey frayer, nbc news, beijing. and up next for us tonight, the hero with that incredible rescue on the tracks. how they got a pilot out alive. next at 7:00 a plea from a bay o'hare health officer. way she is asking everyone to do for the next 30 days. plus calling in the national guard. how troops are helping with covid tests across four bay area counties. nbc bay area news tonight. final tonight on any day a plane crash by itself is dramatic enough but as gadi schwartz tells us, that's where this story of heroism begins. >> reporter: in the history of high stakes rescue, this train versus plane chain of events is a heart pounder. the odds what you just saw might be too incredible to believe. if it wasn't captured by several vantage points a pilot stuck in a cockpit after crash landing on train tracks while in the distance a terrible sound. l.a. pd's police body cam footage showing the true heroism four seconds before impact. the metro commuter train obliterating the small plane, sending debris flying. >> the bells and whistles and flights started flashing i thought, no, this can't be happening i looked down the tracks and i see this train with three huge white lights coming right at us. >> reporter: tonight the pilot is recovering in the hospital the officer who is saved him say to call him lucky is an understatement, especially when you consider how close they were when the plane went down. so this over here, this is your police station. and then we got planes landing over here. this is the intersection where it happened >> that's right. this is right where it happened i think this guy is a very lucky man not only was it right by the police station. i think he cheated death twice in about ten minutes. i think he should buy a lottery ticket >> reporter: all of it coming together in the final critical seconds when those officers transformed into the literal hands of fate. gatti schwartz, nbc news los angeles. >> i want to know his lottery numbers. amazing. that's "nightly news" for this monday. thank you for watching, everyone i'm lester holt. please take care of yourself and each other. good night ♪♪ thousands of women with metastatic breast cancer are living in the moment and taking ibrance. ibrance with an aromatase inhibitor is for postmenopausal women or for men with hr+, her2- metastatic breast cancer as the first hormonal based therapy. ibrance plus letrozole significantly delayed disease progression versus letrozole. ibrance may cause low white blood cell counts that may lead to serious infections. ibrance may cause severe inflammation of the lungs. both of these can lead to death. tell your 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