The first American to die of the Omicron variant was an unvaccinated Texas man who had previously caught COVID-19

• The first American believed to have died of Omicron was an unvaccinated Texan in his 50s.
• The man, who died on Monday, had underlying conditions and had contracted COVID-19 once before.

The first American believed to have died of the Omicron variant was an unvaccinated man from Texas who had already had the coronavirus once before, county officials said.

The man, a Harris County, Texas, resident between 50 and 60 years old, was a high-risk patient due to underlying conditions and his unvaccinated status, a press release from the county said. He died on Monday.

"This is a reminder of the severity of COVID-19 and its variants," Harris County Public Health Executive Director Barbie Robinson said in a statement. "We urge all residents who qualify to get vaccinated and get their booster shot if they have not already."

"Our thoughts and prayers are with the patient's family, and we extend our deepest sympathies," she added.

The man is the first recorded death attributed to the Omicron coronavirus variant in the US.

Harris County Judge Lina Hidalgo also urged people in the county to get vaccinated and boosted in a tweet posted Monday.

As Omicron sweeps the nation, Biden calls for 500 million tests

The Omicron variant now accounts for 73% of all sequenced COVID-19 cases in the US, the Centers for Disease Control and Prevention reported Monday. Previously, the Delta variant was dominant nationwide. That changed last week — just 26% of sequenced cases were Delta for the week ending December 18, according to CDC data.

As the Omicron variant sweeps the nation, cases are up. In the US, the seven-day rolling average for new COVID-19 infections was 132,659 on Sunday, according to data from the CDC. The nation's seven-day average test positivity rate currently stands at 7.2%, higher than the 5% threshold the WHO recommends staying below.

The Harris County man who died Monday is one of at least 808,000 Americans who have been killed by the virus since the pandemic began, according to data from Johns Hopkins University.

Some parts of the country are experiencing even more pronounced Omicron surges. The CDC estimates that in parts of the Northeast, Northwest, Southeast, and Southwest, Omicron now makes up more than 90% of sequenced cases.

In response to the growing crisis, President Joe Biden is announcing new measures on Tuesday to combat Omicron, including delivering 500,000 free at-home coronavirus testing kits to Americans next month. People who need tests will be able to access them using a website set up by health officials. The administration will also deploy military health workers to strained hospitals in January and February, according to the White House.

It's clear that the whiplash arrival of Omicron has changed the game, experts say.

"We have to acknowledge the reality that unfortunately, with a heavy heart, the virus is in charge," Mara Aspinall, an expert in medical diagnostics at Arizona State University, told the New York Times, adding, "We need to take back control, and the only way to do that as a society is to test and isolate, test and isolate, repeat, repeat, repeat."