dallas braiden and glen kuiper will continue to call the a's games. we'll be thinking of him and his family. >> that's going to do it for us. >> "nightly news" is next. tonight, news on covid booster shots and how soon americans may need them. moderna now joining pfizer and urging boosters before the winter. moderna's president speaking out to nbc news. what he said about updating the vaccine against the delta variant. >> i think we're pretty worried now. >> the u.s.eporting over 100,000 cases in 24 hours, but vaccinations rising to their highest level in a month. also, the first day of the new school year for some american students. the battle over masks in the classroom. the historic town destroyed by california's largest

wildfire. homes, businesses and cars wiped out in a matter of hours. the inferno exploding to the size of los angeles, and the new fire threat we're monitoring. the fifth day of travel nightmares for spirit airlines passengers. over half its flights today canceled. how long will it last? new york governor andrew cuomo under mounting pressure to resign over sexual harassment allegations. the new deadline in his impeachment inquiry. and the u.s. women's soccer team bouncing back from disappointment here in tokyo. but in the men's relay, a heartbreaking finish, and my conversation with usa superstar allyson felix, going for gold in her fifth olympics. >> announcer: this is "nbc nightly news" with lester holt reporting tonight from tokyo. >> hello from japan as the olympics round the corner toward the final weekend over competition, we'll have the latest from here just ahead. but first, increasingly alarmed

by the aggressive delta covid variant, the head of vaccine maker moderna tonight telling nbc news he believes booster shots will soon become necessary for those already vaccinated, echoing the same conclusion reached by pfizer. both companies racing to determine just how effective their vaccines remain beyond six months. but the cdc this evening is still not calling for boosters. focusing on increasing first-time vaccinations as the country added 119,000 new covid cases and 641 new deaths according to an nbc news count. and the delta variant fueling new concerns in classrooms and the workplace tonight. we're covering it all, and we begin with miguel almaguer. >> reporter: just as new vaccination rates begin to rise in states where hesitancy is high, tonight moderna joins pfizer saying americans will likely need a booster before winter. moderna says its vaccine remains durable six months second do.

>> both we have today the vaccine is holding up well against the variants of concern, including delta, but we just don't know how long that will last. >> reporter: with nearly 140 million doses of its two-shot regimen administered in the u.s., moderna says research is under way to see if boosters between the three companies offering vaccines can be mixed and matched. the delta variant proving to be a game-changer. >> i think we're pretty worried now. if you look at the delta variant, it took a surprising step. i don't think any of us three or four months ago would predict something this many times more infectious. >> reporter: delta is moving the metrics in a dangerous direction, with new cases spiking in 40 states, deaths,

infections, and hospitalizations are up roughly 40%. >> as the delta variant becomes more prolific, how do your boosters address that variant? >> one of the most important things we need to do is actually bring the delta variant into the vaccine. and that way we're teaching the immune system where the delta variant looks like in our vaccine, just like we did with the prior vaccine. >> reporter: soon children not yet old enough to be vaccinated will return to schools and counties where spread is extraordinarily high. >> there is no question we're going to see outbreaks in schools with this delta variant. the question is how many and how big will they get. >> reporter: as parents begin to return to the office, delta is increasing the risk they too could spread the virus to children still waiting to be vaccinated. >> children under the age of 12 are not just little adults, as we all know. one of the things we need to figure out is what's the right dose. >> reporter: tonight an evolving virus bringing home a new threat. miguel, what are our

experts saying about the return to work for parents when it comes to protecting their children? >> well, lester, they say the risk really depends on where you live and how high the local transmission rate is. doctors say the best way to protect children who are unvaccinated is to make sure people around them are vaccinated. lester? >> all right, miguel almaguer, thank you. and concern over the delta variant and bringing people back to work has many businesses reconsidering their plans. stephanie ruhle joins me now. stephanie, some companies are tapping the brakes here. >> today amazon is the latest company to announce it's pushing back return to office for corporate employees, delaying until january. viacom, cbs, and wells fargo say they'll wait until october. they join other major companies, some also requiring many employees to show proof of vaccination. most recently, microsoft and walgreens. and tonight, harsh consequences for those who don't follow the rules. three employees at cnn terminated for coming to the office unvaccinated, violating company

policy. lester? >> stephanie ruhle, thank you. let's turn to the debate now on wearing masks. perhaps nowhere it is more intense than our schools with conflict, confusion, and little consistency from district to district. gabe gutierrez visited the atlanta area where he got a glimpse of this controversy that could soon be playing out across the country. >> reporter: in dekalb county, georgia, the new school year is already under way, and students like camille kaufman are required to mask up. >> i did not want to go to school if we didn't wear masks. >> her mom agrees. >> if the alternative is to stay home and have another school year in her room, then that would have been pretty devastating. >> reporter: today nearby atlanta public schools opened their doors, lsd with a mask requirement. many of the country's largest districts have similar mandates. last week the cdc abruptly changed its previous guidance, now recommending masks in schools for all students and staff, regardless of vaccination status.

just miles away in gwinnett county, parents have been protesting. allie is so furious, she is pulling her two young daughters from in-person classes. >> it's about choice. i want my children to know that mommy and daddy make their decisions for them, their health decisions. we would never, ever put our children in harm's way. >> reporter: we spoke with her and a group of parents. >> mandate is a very dangerous word. >> this is about parents taking back their power. my children, my decision. period. >> reporter: they agree with florida governor ron desantis, who has banned mask mandate, even threatening to withhold funding from any district that imposes one. several are doing it any way. >> if you're coming after the rights of parents in florida, i'm standing in your way. i'm not going to let you get away with it. records but now the highly contagious delta variant is spreading, just as millions of unvaccinated kids are heading back to

school. >> do more harm than good when it comes to our children. >> our kids are less concerned about wearing masks than we are. >> reporter: tonight it's their parents debating the pandemic's lesson. gabe gutierrez, nbc news, atlanta. in just 60 seconds, a raging wildfire tears through ♪♪ i thought i was managing my moderate to severe crohn's disease. then i realized something was missing... ...me. my symptoms were keeping me from being there for her. so, i talked to my doctor and learned humira is the #1 prescribed biologic for people with crohn's disease. the majority of people on humira saw significant symptom relief in as little as 4 weeks. and many achieved remission that can last. humira can lower your ability to fight infections. serious and sometimes fatal infections, including tuberculosis, and cancers, including lymphoma, have happened, as have blood, liver, and nervous system problems, and new o heart failure. tell your doctor if you've been to areas where certain fungal infections are common

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powerful red flag winds sent the everybody did. >> we have firefighters getting guns pulled out on them because people don't want to evacuate. >> reporter: at 322,000 acres, the dixie fire is now size of lo and the sixth largest fire in california history. more than 60 structures burned with the number expected to rise. >> there were a couple of towers that flamed twice as tall as the trees. huge towers of flame. >> reporter: and tonight firefighters on the front lines of a new threat. the growing river fire is burning in an area that hasn't seen flames in 100 years, with drought-riddled brush ready to ignite, a plea for those in the past to evacuate should the time come. >> finally get allowed back in there. it's either standing or it's a pile of ash. >> reporter: with the fire at the doorstep of another community, another tense and uncertain night lies ahead. steve patterson, nbc news, greenville,

california. it has happened yet again. thousands of passengers hoping to canceled hundreds of additional departures. here is tom costello. r: day five of the spirit airlines meltdown. stranded passengers stuck in hours' long lines weaving through airports nationwide. from ft. lauderdale to san juan, newark to vegas, spirit had promised things would start to improve today. instead, it canceled another 400 flights, 52% of its schedule. after canceling 60% tuesday and wednesday, 40% on monday. more than 1700 flights so far this week. >> they're not even -- everybody is on standby. >> i lost two days of work because of this. >> reporter: spirit says the problem started sunday with weather-related cancellations. add to that the surge in summer travelers, staffing shortages and

computer problems and spirit's dominoes a strong airline in terms of operations. and what happened this week has exposed the problems. >> reporter: leaving passengers s and stuck. >> weairbnb. so we don't have a place to stay as of now. >> reporter: ahead of another busy summer travel weekend. >> well, tom, what can people do if their flights are canceled under these circumstances? >> if the airline cancels the flight, then passengers should be reimbursed for hotel and food, but actually getting on another plane, because all airlines are full right now, that could take days or longer. lester? >> all right, tom costello, thanks. in new york, governor andrew cuomo is so far refusing to accept growing calls to resign after this week's report detailing numerous allegations of sexual harassment, which he denies. kate snow has the latest. >> reporter: holed up at the governor's mansion today, andrew cuomo is increasingly

isolated. >> i think the circle around the governor issmalle >> reporter: ally jacobs heads the democratic party in harassment. what was it in that report that made you change your mind? >> i was personally upset by the magnitude of it and the specificity of it. >> reporter: on wednesday, he called the governor and pleaded with him to resign. it didn't work. >> he was very clear that he had felt that his side of the story had not been fully aired, and he wanted to do that. he didn't think he was being treated fairly. >> reporter: today the state assembly judiciary committee said it's wrapping up impeachment investigation into sexual harassment allegations and also whether cuomo covered up nursing home covid deaths or had staffers help write his book. cuomo asking attorneys to write submissions by the end of next week. phil stack unless cuomo resign, a

lengthy impeachment process seems inevitable. you don't see any way he can survive this politically? >> i don't. >> reporter: while cuomo denies any wrongdoing, jacobs thinks he will eventually recognize he has the step down. >> reporter: the accusers say what's taking so long? >> it's hard. when this is your life, your legacy, your history with your father, and it's all coming to an end. >> reporter: the only one who doesn't see that yet he says is the governor himself. kate snow, nbc news, new york. the head of one of the nation's largest labor unions has died. richard trumka served as head of the afl-cio for more than a decade. he was a third generation coal miner who put himself through law school before rising in the rates. president trump who called trumka a close friend said he died from a heart attack on a camping trip with people everywhere living with type 2 diabetes are waking up to what's possible with rybelsus®. ♪ you are my sunshine ♪ ♪ my only sunshine... ♪

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this week president biden announced the u.s. has ship in order than 100 million doses of vaccine to help the international battle against covid. cynthia mcfadden now on why that's so important to the fight here at home. . >> reporter: an international pandemic requires an international response, and that was the idea behind covax, a multibillion alliance launched to ensure that poor countries would get access to the life-saving vaccines. it hasn't entirely worked out that way. now nearly 18 months into the pandemic, covax has delivered

vaccine to 138 countries, but still only about 15% of the world's population is fully vaccinated, with the highest numbers found in the world's richest countries. >> the greatest threat to our vaccination effort at adequately in vaccination abroad. the delta variant that we're suffering now is a by-product of the virus spreading unchecked abroad. >> reporter: in march, we were given exclusive access to the roll-out of nearly 900,000 covax vaccines in uganda, enough to fully vaccinate about 1% of the population. distribution is time consuming and expensive, which we saw as the unicef team delivered 40 precious doses to the boubuma island. it's wonderful to have this, yet it's a much smaller amount than you hoped.

>> reporter: this doctor helped to eradicate smallpox. he says we don't have a choice to vaccinate the rest of the world. countries and others variants. >> reporter: so while the biden administration's gift of 100 million doses with a promise of more to come is welcome, it still leaves covax woefully underresourced. perhaps the minister of health in uganda said it best. >> let every human life matter. we have to hold hands together if we are going to win this war. >> reporter: to date, less than 2% of those living in the developing world have been vaccinated, and that is a problem for everyone. cynthia mcfadden, nbc news. here in tokyo, it's been a day of notable ups and downs for team usa. we get more on that from tom llamas. >> reporter: tonight triumph and defeat for team usa on the track.

ryan crouser bringing home the first gold on the men's side for track and field with this record breaking push. carouser and joe kovacs going one, two shot put. carouser sharing a message to his late grandfather. >> i was lucky enough to talk to my family back home. they stayed up late. i felt like they were actually here. >> reporter: nageotte in pole vault. >> the united states has some ground to make up. >> reporter: and a shocking finish in the 4x100 meter relay after sloppy baton handoff, the american men failing to advance to the final. sprinter carl lewis tweeting the team did everything wrong, call it a total embarrassment and completely unacceptable. >> the bronze medal on the line. >> reporter: tonight the u.s. women's soccer team celebrating after beating out australia for bronze. >> i just wanted to win. that's really it. win and be the best

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she's headed to the 400 meter final again. allyson felix, the most decorated runner u.s. history with nine olympic medals. she shared with me why her last olympics may also be her most meaningful. allyson felix says her fifth olympics is about a lot more than medals. she is running for progress, for equality and for her daughter. >> i feel like becoming a mother changed me in every possible way. i mean, it showed me how strong i was. >> reporter: in 2018, felix, just 32 weeks' pregnant was submitted to the hospital with severe pre-eclampsia, a life-threatening complication. her daughter camron

was born weighing 3 pounds, 7 ounces. >> i was literally sitting there watching her fight every single day. running was the furthest thing of my mind. all my energy was going into making sure she was okay. >> reporter: kamron spent a month in the nicu. and then lo and behold, she is out watching you run. >> i can't believe how far we have come. >> she is off to the olympics being a mom. >> reporter: but the road back to competition wasn't easy. at first, felix could barely walk 30 minutes on a treadmill left the elite athlete in tears. people kind of expect you to be super woman. >> and you expect yourself to be able to be super woman as well. and then you go through a real life experience and you are just grateful for your life. >> that experience also led felix to activism, testifying before congress about black maternal mortality. >> we need to provide women of color with more support during their pregnancies. >> and penning a raw

op-ed about her frustration with her now former sponsor nike, writing "i asked nike to contractually guarantee that i wouldn't be punished if i didn't perform at my best in the months surrounding childbirth. if i, one of nike's most widely marketed athletes couldn't secure these protections, who could? nike declined. the way you stood up for women, women of color, mothers, that was a big risk. >> it was terrifying, you know. there had been silence around, you know, the culture of pregnancy in sport for too long. and what i was experiencing, i couldn't just sit back and just let it go. >> soon after she and others spoke out, nike announced expanded protections for pregnant women, and this year felix started her own shoe company on her terms. now admired as much for her advocacy as for her athleticism. >> this is so much bigger than just running fast. it's showing women

that we can be present at home, and we can also thrive in our professions. >> there is camron in mommy's arms. >> it's integrity. >> that's "nightly news" for this thursday from tokyo. you can watch all the olympic action tonight here on nbc. and a program note, a new episode of "nightly news" kids edition from tokyo is streamin g right now at 4:00. how far away are you from needing the booster shot. >> i'm aging, and soy need a booster. >> the new numbers on the advice

as doctors of the new variant is driving up cases. it won't be long before levi's stadium is opening to thousands of stands. we will tell you what the 49ers had to do to make sure that covid doesn't come in as well. redemption for team usa and the women's national soccer team earns a spot on the podium. >> that is what this team does. we never give up. we always fight. >> we will take you live for tokyo for what we can watch tonight in primetime. the news at 4:00 starts now, and thank you for joining us on this olympic edition of nbc bay area. >> and we will go live to tokyo in a few minutes, but right now, brace for a booster, because moderna said that while the covid vaccine protection is holding up, people will need a booster within months. and cdc has said that they are not ready to say that the boosters are ready. and we have this report that while some people are not