The new omicron variant makes up nearly 100% of the strains found in wastewater samples in Orlando, Florida, officials said Thursday.

"It escalated rapidly," Orange County Utilities spokeswoman Sarah Lux told ABC News.

In its first test for the variant last Thursday, the department found no evidence of omicron in the community's wastewater, she said. On Saturday, it represented about 30% of the strains found in the samples, and by Tuesday, nearly 100%.

"So, we're talking about zero to nearly 100 in a matter of a week," Lux said.

All parts of the county are seeing an increasing presence of the omicron variant, she said. The southern area, home to the theme parks, has seen the highest amount of virus remnants, followed by the eastern area, which is home to the University of Central Florida.

-ABC News' Arielle Mitropoulos

The CDC's advisory committee recommended Thursday that people who have a choice should get an mRNA vaccine, either Pfizer or Moderna, over the single-shot Johnson & Johnson vaccine after a review of new CDC data on rare blood clots linked to J&J.

The vote was unanimous.

The rare blood clots are not a new safety concern and the vaccine has already become far less common in the U.S. after it was given an FDA warning label about the clotting condition. But more data that confirmed a slightly higher rate of clotting cases and deaths than was previously reported caused the CDC and FDA to take another look at the data this week.

The CDC has confirmed nine deaths and 54 cases from the severe clotting event, thrombosis with thrombocytopenia.

There could also be more cases and deaths because TSS is under-diagnosed and could be underreported, the CDC said.

The clotting is more common among women in their 30s and 40s but has been seen in adult men and women of all ages.

The experts said J&J should not be taken off the shelves and is still far more beneficial than not getting any vaccine at all.

-ABC News' Cheyenne Haslett

Maine and New Hampshire are now averaging more new cases than at any other point in the pandemic, while daily cases in Massachusetts, Vermont, Connecticut, Pennsylvania and Rhode Island are nearing peak levels, according to federal data.

Five of those states -- Connecticut, Maine, Massachusetts, Rhode Island and Vermont -- have the highest full vaccination rates in the country.

In Florida, which has been largely spared from the latest COVID-19 wave, daily cases have increased by 92% over the last two weeks, according to federal data.

-ABC News' Arielle Mitropoulos

COVID-19 cases in New York City have tripled in the last month, officials warned Thursday.

Mayor Bill de Blasio announced a six-point plan to fight the surge, including increasing testing capacity, doubling down on business inspections and distributing 1 million KN95 masks and 500,000 rapid home tests.

"We need to stop this variant," the mayor said. "This variant moves fast. We need to move a lot faster."

-ABC News' Aaron Katersky

A journalist traveling alongside U.S. Secretary of State Antony Blinken on his visit to Southeast Asia has tested positive for COVID-19 in Malaysia, according to U.S. Department of State spokesperson Ned Price.

Meanwhile, Blinken and his senior staff all tested negative for COVID-19 upon arrival in Kuala Lumpur on Tuesday night. The member of the traveling press pool who tested positive had last tested negative in Indonesia's capital, their previous stop, on Tuesday.

"The individual who tested positive will remain in isolation," Price said in a statement Wednesday, "and we will continue to adhere to and go beyond CDC guidance, including with our rigorous testing protocol, for the remaining traveling party."

Blinken has canceled a scheduled trip to Thailand "out of an abundance of caution" and will return home to the United States, according to Price.

"The Secretary expressed his deep regret to the Foreign Minister that he would not be able to visit Bangkok this week," Price said. "He explained that, in order to mitigate the risk of the spread of COVID-19 and to prioritize the health and safety of the U.S. traveling party and those they would otherwise come into contact with, the Secretary would be returning to Washington, D.C. out of an abundance of caution."

"The Secretary extended an invitation for the Foreign Minister to visit Washington, D.C. at the earliest opportunity and noted that he looked forward to traveling to Thailand as soon as possible," Price added. "They affirmed that they would use the upcoming engagements to further deepen the U.S.-Thai alliance."

The U.S. Embassy in Malaysia confirmed that the infected individual "was not involved and has not participated in any of Secretary Blinken's program in Kuala Lumpur."

"The sole member of the traveling party who tested positive is observing all requirements of the Ministry of Health," the embassy said in a statement Wednesday. "We confirm all other members of the party tested negative for COVID-19 upon arrival in Malaysia."

Blinken was in Indonesia on Tuesday, and the U.S. Embassy in Jakarta confirmed that no members of the traveling party tested positive for COVID-19.

All members of the U.S. delegation are required to be vaccinated against COVID-19 and undergo regular testing on trips.

-ABC News' Conor Finnegan