Dr. Deborah Birx warned on Sunday that the escalating coronavirus surge is likely to be the most trying event in U.S. history, as hospital systems around the country strain to combat its mounting daily death toll.”This is not just the worst public health event. This is the worst event that this country will face, not just from a public health side,” Birx, the White House coronavirus response coordinator, said during a masked appearance on NBC’s “Meet the Press.”Birx’s comments add to a chorus of public health officials expressing concern about the growing wave of infections.On Wednesday, Centers for Disease Control and Prevention Director Dr. Robert Redfield said that the coming months will be “the most difficult time in the public health history of this nation.””This fall/winter surge is combining everything that we saw in the spring with everything we saw in the summer — plus the fall surge going into a winter surge. I think that’s why Dr. Redfield made this absolute appeal to the American people,” Birx said.The Covid-19 pandemic is killing record numbers of Americans on a daily basis, and the numbers are expected to worsen as a result of gatherings held for the Thanksgiving holiday.More than 2,000 people in the U.S. are dying from Covid-19 on a daily basis, according to data compiled by Johns Hopkins University. On Thursday, more than 2,800 deaths from the disease were recorded, a new high.Birx called on Americans to change their behavior ahead of the winter holidays. Despite her dire warning, she said that at this point “we know what behaviors spread the virus and we know how to change those behaviors.””We cannot go into the holiday season, Christmas, Hanukkah, Kwanza, with the same kind of attitude, that those gatherings don’t apply to me,” Birx said. “They apply to everybody.””If you do not want to lose your grandparents, your aunts, let’s be clear: If you’re over 70, 20 percent of those over 70 who contract Covid are hospitalized, and still, 10 percent of them are lost,” Birx added.”So if you have anyone in your family with comorbidities or over 70, you cannot do those things. You cannot gather with your mask off, you cannot hug and kiss people outside,” she said.Birx acknowledged the existence of a number of vaccines that have shown promising results in clinical trials. But, she said, those won’t be available for the most vulnerable Americans until February.”So we need to do this now. Yes, the nursing homes will be vaccinated, but there are 100 million Americans that have these comorbidities that put them at substantial risk,” Birx said, referring to underlying medical conditions that can make people more vulnerable to the virus.Health and Human Services Secretary Alex Azar said on ABC’s “This Week” on Sunday that “more general vaccination” could be available around February or March, and that there would be enough vaccines for every American seeking one by the second quarter.The frustration and alarm from a senior member of the White House’s effort to combat the virus stands in contrast to the relative silence from the president himself.President Donald Trump, who will leave office next month, has avoided mentioning the death toll from the disease. He has instead remained focused on personal grievances since losing the November election to President-elect Joe Biden.Biden’s team began formally coordinating with the current administration’s Covid-19 response officials last week, after a delay caused by the White House’s efforts to delay the formal transition.Dr. Anthony Fauci, the longtime director of the National Institute of Allergy and Infectious Diseases, said on Thursday that he agreed to serve as Biden’s chief medical advisor. He was scheduled to brief Biden’s team the same day.