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.

Starting Wednesday, Dec. 16 through Jan. 10, all non-essential stores and schools will be closed in Germany and social meetings will be limited to five people from two households, with an exception made for the Christmas period from Dec. 24 to Dec. 26 when four more people beyond a household will be allowed.

No exceptions will be made for New Year's Eve.

COVID-19 transmissions remain high in the country despite softer restrictions in place. As of Dec. 13, the Robert Koch Institute reported a total of 20,2000 new cases and 321 deaths, bringing the totals to 1,320,716 and 21,787, respectively.

Germany had initially planned for a "semi-lockdown," allowing for a holiday exemption from Dec. 23 to Jan 1 where up to 10 people from two households could meet but those plans were scrapped in favor of these new rules.

ABC News' Christine Theodorou contributed to this report.