Lifestyle Health Unvaccinated Houston Man First Known Death in the U.S. from Omicron COVID Variant Cases of COVID-19 with the omicron variant now account for 73% of all new infections in the U.S. By Julie Mazziotta Julie Mazziotta Twitter Julie Mazziotta is the Sports Editor at PEOPLE, covering everything from the NFL to tennis to Simone Biles and Tom Brady. She was previously an Associate Editor for the Health vertical for six years, and prior to joining PEOPLE worked at Health Magazine. When not covering professional athletes, Julie spends her time as a (very) amateur athlete, training for marathons, long bike trips and hikes. People Editorial Guidelines Published on December 21, 2021 12:04 PM Share Tweet Pin Email Houston hospital workers cover a patient who died of COVID-19. Photo: Go Nakamura/Getty An unvaccinated man in Houston is the first known death in the U.S. from the omicron variant of COVID-19, Texas health officials said Monday. The man was in his 50s and had tested positive for the omicron variant before his death, officials in Harris County said. Along with being unvaccinated, he had preexisting conditions and had a previous case of COVID-19. "Our thoughts and prayers are with the patient's family, and we extend our deepest sympathies," Barbie Robinson, HCPH executive director, said in a press release. Robinson emphasized the need for vaccination to prevent severe illness and death. "This is a reminder of the severity of COVID-19 and its variants," she said. "We urge all residents who qualify to get vaccinated and get their booster shot if they have not already." COVID Variant Omicron Now Accounts for More Than 70 Percent of U.S. Cases, CDC Says In Harris County, just over half of residents — 58.7% — are fully vaccinated against COVID-19, according to the Texas Department of State Health Services. The omicron variant was first identified in the U.S. on Dec. 1 and in just two weeks already become the dominant variant, accounting for 73% of all new cases between Dec. 12 and 18, the Centers for Disease Control said Monday. The variant is highly contagious — the week prior, omicron represented just 12% of new cases. The majority of omicron infections are in the New York and Pacific Northwest, where omicron accounted for 90% of new cases last week. RELATED VIDEO: Doctor Says Fully Vaccinated People Are Going to Test Positive with Omicron: 'Our New Normal' Omicron appears to produce a milder illness than previous variants like delta, researchers have found. In a large study of omicron patients in South Africa, most had mild symptoms or were asymptomatic, and recovered in just a few days. Patients typically reported experiencing a scratchy throat which then transitions into nasal congestion, a dry cough and muscle aches and pains. The variant does seem, though, to evade vaccines. Researchers tested the antibodies of people who received various COVID-19 vaccines and found that they are all less effective against omicron than previous variants. The typical two-dose series of Pfizer offered just 34% protection, and Johnson & Johnson and AstraZeneca had little to no effect against the variant. A booster dose, though, did significantly increase protection — a study from the U.K. found that a third dose of Pfizer was 75% effective against omicron. And though the vaccines are less effective in preventing infection with omicron, they are still extremely protective against severe illness that could lead to hospitalization or death. Omicron Is Moving Fast — but a Booster Shot Offers Significant Protection from Infection Dr. Anthony Fauci, the nation's top infectious disease expert, said Wednesday that a booster shot will protect against infection from omicron, and that Pfizer and Moderna do not need to formulate an omicron-specific booster shot. "Our booster vaccine regimens work against omicron," Fauci said, according to The New York Times. "At this point, there is no need for a very specific booster. And so the message remains clear: If you are unvaccinated get vaccinated, and particularly in the arena of omicron if you are fully vaccinated, get your booster shot." As information about the coronavirus pandemic rapidly changes, PEOPLE is committed to providing the most recent data in our coverage. Some of the information in this story may have changed after publication. For the latest on COVID-19, readers are encouraged to use online resources from the CDC, WHO and local public health departments. PEOPLE has partnered with GoFundMe to raise money for the COVID-19 Relief Fund, a GoFundMe.org fundraiser to support everything from frontline responders to families in need, as well as organizations helping communities. For more information or to donate, click here.