Thirty-five juveniles and 116 adults were arrested at a "super spreader" underground party this weekend in Palmdale, California, said Los Angeles County Sheriff Alex Villanueva.

The sheriff said the party was in clear violation of the governor's stay-at-home order, adding that the party would have been targeted without the pandemic due to allegations of drugs, weapons, prostitution and underage trafficking.

ABC News' Alex Stone contributed to this report.

Massachusetts will roll back its reopening plans on Sunday as cases and hospitalizations rise in the aftermath of Thanksgiving, Gov. Charlie Baker said.

Capacity will be reduced from 50% to 40% in facilities including offices, gyms, places of worship and retail stores, Baker said.

In offices, people must wear masks when they're not alone, and at gyms, customers must wear masks at all times.

Changes are also coming to Massachusetts restaurants. Customers must wear masks at all times except when eating and drinking, and their time at tables will be capped at 90 minutes.

Dr. Anthony Fauci and White House coronavirus response coordinator Dr. Deborah Birx warned Tuesday that the U.S. hasn't yet seen the full impact of Thanksgiving gatherings.

“We have not yet seen the full blunt and the effect of the traveling and the congregating,” Fauci said at The Wall Street Journal's CEO Council summit .“That should be sometime probably next week, or a week and a half.”

"Then we're going to enter into the Christmas season, again, with more traveling and with more congregating at family and social gatherings. So we're in for a very challenging period," Fauci continued. "And the only way we're going to counter that is by a consistent uniform implementation and adherence to public health measures."

Fauci also said he’s accepted President-elect Joe Biden’s offer to become his chief medical adviser.

“I've already told the president-elect that I would gladly accept that responsibility. It really is very similar to what I'm doing now,” Fauci said.

ABC News' Anne Flaherty contributed to this report.

The University of Michigan said this Saturday's football game against Ohio State is now canceled due to "an increasing number of positive COVID-19 cases and student-athletes in quarantine over the past week."

"The number of positive tests has continued to trend in an upward direction over the last seven days," said Michigan's Athletic Director, Warde Manuel. "We have not been cleared to participate in practice at this time. Unfortunately, we will not be able to field a team due to COVID-19 positives and the associated quarantining required of close-contact individuals."

ABC News' Josh Hoyos contributed to this report.

U.S. President-elect Joe Biden on Monday announced key nominations and appointments of his health team, a slate of experts and public officials who will lead his administration's response to the coronavirus pandemic.

"This trusted and accomplished team of leaders will bring the highest level of integrity, scientific rigor and crisis-management experience to one of the toughest challenges America has ever faced -- getting the pandemic under control so that the American people can get back to work, back to their lives and back to their loved ones," Biden said in a statement. "This team of world-class medical experts and public servants will be ready on day one to mobilize every resource of the federal government to expand testing and masking, oversee the safe, equitable and free distribution of treatments and vaccines, reopen schools and businesses safely, lower prescription drug and other health costs and expand affordable health care to all Americans, and rally the country and restore the belief that there is nothing beyond America's capacity if we do it together."

California Attorney General Xavier Beccera is nominated to serve as the Secretary of Health and Human Services.

Dr. Vivek Muthy, a physician and research scientist, is nominated to be the Surgeon General, a role he served during the Obama administration.

Dr. Rochelle Walensky, an expert on virus testing, prevention and treatment, is nominated to serve as director of the Centers for Disease Control and Prevention.

Dr. Marcella Nunez-Smith, an expert on health care disparities, will serve as the COVID-19 Equity Task Force Chair.

As Biden said last week, Dr. Anthony Fauci will stay on in his current role as director of the National Institute of Allergy and Infectious Diseases. Fauci will also serve as Biden's chief medical adviser on COVID-19.

Jeff Zients, co-chair of Biden's transition team who led the Obama administration's National Economic Council, will serve as coordinator of the COVID-19 Response as well as counselor to the president.

Natalie Quillian, a national security expert, will serve as deputy coordinator of the COVID-19 response.

ABC News' John Verhovek contributed to this report.