♪ this is "nightline." >> tonight, divided nation. >> this election is over. >> president-elect joe biden moving ahead and president trump refuses to concede. covid cases explode in america just days after winning with running mate, kamala harris. >> i may be first woman in this office, i will not be the last. plus covid game changer. promising results of new vaccine trial, dr. boeser here to break it down. remember be alex, celebrating the legendary game show host in his own words, how he wanted to be remembered.

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good evening, thank you for joining us, joe biden and kamala harris won't be sworn into office for another 2 1/2 months. but already unveiling a plan to combat the pandemic. while donald trump and his allies double down on unfounded election claims and rebuff calls

to concede. >> i will spare no effort to turn this pandemic around once we're sworn in january 20th. >> reporter: president-elect joe biden today making it clear, his first order of business, tackling the covid-19 pandemic that's now killed nearly a quarter million americans. primary message, wear masks, specifically imploring those who resist it. >> it's not to make your life less comfortable or take something away from it. it's to give something back to all of us, a normal life. >> reporter: biden's remarks coming on the heels of the most promising vaccine news to date, pfizer saying there's is effective presenting infection. on the run after waiting four days to be announced the winner. >> joseph biden jr. is on track to win the state of

pennsylvania, become the 46th president of the united states. >> reporter: in several u.s. cities, democratic strongholds, spontaneous celebrations erupted. on saturday night, the culmination of incredible run for president, once thought to be too old, white and out of touch with today's democratic party, celebrating with his running mate, senator kamala harris. >> we've won with the most votes ever cast for a presidential ticket in the history of the nation, 74 million. >> reporter: biden reaching out to the 71 million who did not vote for him. >> for all those of you who voted for president trump, i understand the disappointment tonight, i've lost a couple of times myself. but now let's give each other a chance. it's time to put away the harsh rhetoric, lower the temperature, see each other again, listen to

each other again. and to make progress we have to stop treating our opponents as our enemies. they are not our enemies, they're americans. >> reporter: harris shattering the vice presidential mold, becoming first woman to win the second highest office in the land. >> while i may be the first woman in this office, i will not be the last. because every little girl watching tonight sees that this is a country of possibilities. >> reporter: president trump still refusing to concede, spending the weekend golfing at his virginia resort. his campaign taking the fight to court, questioning the validity of the votes in key swing states. >> this election is not over, far from it. >> reporter: there's been no evidence to back up any of the allegations that team trump have

made. president-elect biden bringing to the white house a decidedly different style. born in 1942, spent early years in northeast pennsylvania, scranton. family moved to delaware, biden would launch career in politics. 29 years old elected to u.s. senate in 1972. but just a month later, tragedy struck. biden's wife and baby daughter killed in a car crash. sons beau and hunter also seriously injured. nearly resigned his senate seat but served. sworn in at hospital. >> do you solemnly swear -- >> i do. >> reporter: commuting from d.c. to delaware every nig on amtrak. 1977, married second wife jill.

>> we don't use term stepmother. >> we have a mom and mommy. mommy died, this is our mom. >> reporter: and they had a daughter, ashley. biden spent 36 years in the senate and launched two unsuccessful campaigns for the white house. in 1998 and in 2008, where he faces barack obama, obama tapping biden to be his vice president. beginning of a deep and enduring friendship. >> for the final time as president, i am pleased to award our nation's highest civilian honor, the presidential medal of freedom. >> reporter: right before they left office in 2013, obama surprised biden with the presidential medal of freedom, highest honor given to civilian in america. obama would also be there to comfort biden when his son beau died from brain cancer. >> beau biden brought to his work a mighty heart, to his

family a mighty heart. >> reporter: a grief-stricken biden decided not to run for president. but it was president trump's reaction to the unite the right rally in charlottesville, virginia. >> you also had very fine people on both sides. >> reporter: that compelled biden to change his mind, throw hat in the ring one more time. >> at that moment i knew the threat to this nation was unlike any i had ever seen in my lifetime. >> reporter: not auspicious start but propelled by black voters, surprising frontrunner and then nominee for the democrats. >> if you entrust me to the presidency, i'll draw on the best of us, not worst. >> reporter: anything but traditional shl

traditional, in midst of pandemic, president had huge rallies. biden always wearing a mask, had smaller events. he and his running mate accomplished what is only done four times in history, beat incumbent president. >> we're here to bring this home. >> reporter: grew up in california, daughter of immigrants, jamaican father and indian mother, primarily raised by mom. part of a bussing program to integrate berkeley's public schools, going on to star on debate team on howard university. >> do not listen when they say it can't be done. howard taught me and it has taught you, you can do anything and you can do everything. >> reporter: after graduation from law school, she was the first female san francisco district attorney, then became california's attorney general in 2011. during that time she forged a bond with delaware's attorney

general, beau biden. >> i got to know joe in large part through beau's relationship with his father. >> reporter: in 2016, harris easily won race for u.s. senate, sworn in by her future running mate. she launched a presidential run herself in 2019. >> america does not want to witness a food fight, they want to know how we're going to put food on their table. >> reporter: dropping out before any votes were cast. when biden became the democratic nominee, he repeated history like obama, tapping former rival to join the ticket. facing a raging pandemic, tattered economy and polarized nation, newly elected team is not intimidated by the challenges. >> we stand at an inflection point. we have an opportunity to defeat despair, build a nation of prosperity and purpose. we can do it, i know we can.

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now the ceo of the robert wood johnson foundation. pfizer announced the results, what's your reaction? >> i think it's exciting. i always urge caution until a company's results have been validated by impartial scientists. but when you have a vaccine that's more than 90% effective, that can be a game changer, along the same level of protection you get from measles vaccine. and fda had set threshold for approval, above 50% in reduction of risk. exciting news. >> dr. fauci called the effective rate extraordinary and unexpected. did you ever think we'd get a vaccine this successful to deal with such a deadly virus? >> well, you always hope you're going to get a vaccine as good as measles, some of the best out

there. but there are a lot of vaccines where the level of protection is nowhere near that. each year we encourage people to get the flu vaccine knowing in a good year it will reduce your risk about half. so this vaccine has some challenges in terms of how you distribute it. will take a while to ramp up production, but if it holds up and it's as effective in longer periods of time as it's shown in the seven-day evaluation, could be incredible. >> we know it's early but what do we know about the safety of the vaccine? >> we don't know a lot yet, fda is requiring companies to follow patients full two months and it's not through that full period. this vaccine is using a new technology, are mrna, never been used for vaccine in humans before. it's really important to follow

people even longer than that, larger populations, and make sure the vaccine is not only effective but safe. >> doc, as you know, pfizer and three other companies are in late stage trials. when can the american people expect a vaccine to be widely available? >> you know, there's a lot of effort going into planning. vaccines where the government has already paid to have the vaccines be manufactured so if they're effective, they can start to roll out. there's been a lot of planning by the cdc and state health departments in terms of how they would distribute vaccines when they're available, but this vaccine, if it pans out, it's not going to have big impact this winter. in early course will go to health care providers, those in positions of greatest risk, but not widely distributed to the general public until spring or later. >> doc, cases have never been higher in our country, passed 10

million cases today and another surge is sweeping the country. is there anything we can be doing to get it under control before the vaccine comes? >> there is so much we can be doing. one, we need to come together as a nation and recognize that following the recommendations of public health is best way to get economy up and running in sustained way, the best way to protect each other, to make sure our children are safe, our parents are safe, those in our communities are safe. i'm hoping now the election is over, we can see governors stepping up and mandating masks in each of their states. just saw utah do that, a terrific move. we estimate if everyone in america wore masks appropriate time and interactions, there would be tens of thousands of lives that could be saved. that's a small thing to ask people to do. >> any concern at all that news

of a possible vaccine may give the public a false sense of security? >> it's given me real concerns throughout this. lot of people saying there's a vaccine around the corner, why do i need to inconvenience myself by wearing a mask, keeping away from others, or limiting my behavior. those are the things that will save lives this winter. and the story's not fully in yet on this vaccine. this news is encouraging, we need to see a longer period of time, 28 days to see how it protects at that point. we need to see how it does against serious covid infections. this initial result was against all infections and fda wants to see how it protects the most serious infections and then we need to look at safety data. this is encouraging but we're not there yet. i hope people will step up. winter is viruses' high time.

they survive longer and stay in the air and we spend time indoors, that favors the virus. >> you talked about this plenty of time, this notion of fatigue. world has been dealing with this a long time. any sense with the vaccine coming down the road, you think when the world might get the virus under control? >> i do worry about the issue of fatigue. but as you look across the nation, states that thought because they were rural and less densely populated, they didn't have anything to worry about, we're seeing cases skyrocketing, hospitals fill up and states having to put in mobile hospital units. i'm hoping that sense of fatigue doesn't overcome people's ability and willingness to do those measures that will save lives, because the models are only a prediction. we have the ability to make those modelers wrong by doing

things to reduce the spread of this disease in our country. i hope we can come together as americans and do it for each other. >> dr. richard besser, always grateful for your time and expertise, see you down the road. >> thanks for having me, great talking with you. up next, final jeopardy with host alex trebek, how he inspired the next generation. >> announcer: abc news "nightline," sponsored by i robot. experience clean in a whole new way. now roomba offers you personalized cleaning suggestions and vacuums exactly where you need it. by getting to know you and your home, roomba makes cleaning easier than ever before. so say goodbye to cleaning and hello to clean. hey google, tell roomba to vacuum the dining room table. roomba and the irobot home app.

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the outpouring of tributes coming in for the beloved "jeopardy!" host, his absence felt around the globe. >> alex trebek. >> alex trebek sharing the wonders of the world to millions of families each night, inspiring them to strive for greatness. >> i'm an immigrant, like a lot had a hard time learning english. growing up, grandfather would sit me on his lap and we would

watch you, and i credit you for my perfect diction, thank you. >> trebek brave throughout his battle with pancreatic cancer. telling how important fans were to him. >> most important element of my life outside of family and friends. can't help but be touched by what they say. stop worrying about the future, treat every day as a blessing and enjoy it to the fullest. and try to be aware of when you leave this earth that you've made a difference in the lives of other people. >> there's no question, he's left a lasting legacy of compassion and kindness. >> how would you like to be remembered? >> oh, gosh, as a decent guy who did his best to help the

contestants perform, and if that's the way they remember me down the line, perfectly happy with that. >> alex trebek was 80 years old. that's "nightline" for this evening. watch full episodes on hulu, see you back here same time tomorrow. thanks for the company, america, good night.