COVID-19 updates: Michigan, Minnesota, New Mexico leading nation in cases

All fully vaccinated adults in Kansas and Maine can now get a booster if it's been six months since their Pfizer or Moderna dose or two months since their Johnson & Johnson shot, the governors said.

“Expanding access to booster shots will help us put an end to this deadly pandemic," Kansas Gov. Laura Kelly said in a statement.

Nirav D. Shah, director of the Maine CDC, said, "Given the high level of COVID-19 transmission occurring in Maine, we want Maine people to be clear that all adults are now eligible for a booster."

Booster eligibility has been expanded to all adults in several other states, including New York, New Jersey, Arkansas and Colorado.

For the first time in more than two months, U.S. death rates are not predicted to decline in the weeks to come.

Forecast models used by the CDC are predicting that weekly death totals will likely remain stable or have an unknown trend in the next four weeks, with thousands more Americans expected to lose their lives by early December.

The model -- from the COVID-19 Forecast Hub at UMass Amherst -- expects around 14,400 more virus-related deaths in the U.S. over next two weeks, with a total of around 791,100 American lives lost by Dec. 11.

-ABC News' Arielle Mitropoulos

Dr. Anthony Fauci said Tuesday that booster doses may become the standard for a "full" vaccination.

"I happen to believe as an immunologist and infectious disease person that a third shot boost for an mRNA [vaccine] ... should be part of the actual standard regimen, where a booster isn't a luxury. A booster isn't an add-on and a booster is part of what the original regimen should be. So that when we look back on this, we're going to see that boosters are essential for an optimal vaccine regimen," Fauci said in a pretaped interview aired at the 2021 STAT Summit.

-ABC News' Sasha Pezenik

Washington, D.C., will lift its indoor mask mandate on Monday.

"Instead of following a blanket mandate, residents, visitors, and workers will be advised to follow risk-based guidance from DC Health that accounts for current health metrics and a person’s vaccination status," Mayor Muriel Bowser's office said in a statement

Private businesses can still require masks.

Masks will still be required in places including public transportation, schools, child care facilities and nursing homes.

The White House will still require masks indoors, a White House spokesman said, because D.C. has a "substantial" level of community transmission, according to the CDC.

"The White House follows CDC guidance which recommends masking in areas of high or substantial transmission," the spokesman, Kevin Munoz, told ABC News.-ABC News' Beatrice Peterson, Ben Gittleson