Massachusetts Gov. Charlie Baker said he's activating 500 more National Guard members to support the state's strained health care system.

Baker had activated 250 National Guard members when students returned to classrooms in the fall to help with school transportation, ABC Boston affiliate WCVB reported.

In Maine, Gov. Janet Mills is activating up to 169 National Guard members to help overrun hospitals, ABC affiliate WMTW reported. Maine hit a hospitalization record Monday with over 400 COVID-19 patients in hospitals, according to WMTW.

New Orleans will reinstate its indoor mask mandate beginning Wednesday as the city gears up for Mardi Gras celebrations.

Masks will be required in restaurants, bars, gyms, entertainment venues and public transportation.

About 64.6% of New Orleans residents are fully vaccinated, according to the city.

People 5 and older must show proof of vaccination or a negative test to access indoor restaurants, bars, entertainment venues, bowling alleys, indoor playgrounds, arcades and similar settings.

Omicron is estimated to account for 98.3% of new cases in the U.S. as of Jan. 8, according to new data released by CDC Tuesday. (These figures are calculated using modeling and may not be exact.)

Delta now accounts for only 1.7% of new cases nationally, forecasters estimate.

In three areas of the country -- the deep South, the Southeast and the New York/New Jersey region -- omicron is estimated to account for more than 99% of new cases.

In early December, omicron was estimated to account for just 0.6% of all new cases.

-ABC News' Arielle Mitropoulos

The White House has been limiting its in-person gatherings to 30 people "over the last several weeks" due to the omicron surge, White House press secretary Jen Psaki said.

“We wear masks in the West Wing at all times, including in your office, unless you're in your office alone,” Psaki said.

-ABC News' Ben Gittleson

West Virginia Gov. Jim Justice announced Tuesday evening that he tested positive for COVID-19 and is experiencing moderate symptoms.

Justice, 70, who is fully vaccinated against COVID-19 and has received a booster shot, said he has started a course of monoclonal antibody treatment, as recommended by his physicians. Everyone who has been in close contact with the governor over the past few days is being notified. His wife, Cathy Justice, tested negative for the virus on Tuesday evening, according to a press release from the governor's office.

The governor was scheduled to deliver his State of the State address that night but was forced to do so via a written statement to the West Virginia Legislature instead.

"I feel extremely unwell at this point, and I have no choice but to postpone my State of the State address to the Legislature," Justice said in a statement Tuesday evening. "I woke up this morning with congestion and a cough. A little while later, I developed a headache and fever, so I decided to get tested right away."

"The rapid test that I took came back negative, but by the late afternoon, my symptoms were still getting much worse," he continued. "My blood pressure and heart rate were extremely elevated, and I had a high fever. Finally, my PCR test results this evening confirmed I was positive. Because of all this, I began receiving my antibody treatment and I hope this will lessen these symptoms."