Now Las Vegas’s in-person Consumer Electronics Show (CES), held at the start of January, looks to be on thin ice after several corporate heavyweights either scaled back their plans for the annual tech mecca, or dropped out altogether.

Omicron has spread much faster than scientists previously expected, and on Monday the World Economic Forum highlighted the new strain’s transmissibility as it scrapped plans to bring the most influential people from around the globe to its annual summit in the Swiss skiing resort of Davos. Omicron is already the dominant strain in the United States, where it accounts for 73% of all new cases.

The CES cancellations have come from a swath of major companies. T-Mobile USA, the largest 5G network provider in the country, said late on Tuesday that the “vast majority” of its team—including CEO Mike Sievert—will not be traveling to the event despite the organizer’s efforts to ensure a safe show. 

“After careful consideration and discussion, T-Mobile has made the difficult decision to significantly limit our in-person participation,“ the telecom group said in a statement, adding that it would continue to serve as a CES sponsor.

Citing the health and safety of their employees, other companies that have announced they will not send people to CES include Amazon, Pinterest, Facebook parent Meta, and Twitter.

“Due to the quickly shifting situation and uncertainty around the Omicron variant, we will no longer have an on-site presence at CES,” Amazon said in a statement cited by Bloomberg. 

Only for the vaccinated

With each high-level executive who decides to forgo the event, it becomes less attractive for others to attend, since it is a trade show for industry professionals. 

Gary Shapiro, head of the Consumer Technology Association (CTA), which organizes the CES, told VentureBeat in late November that he already expected only about half of the 171,268 visitors that showed up at the last physical event, held in early 2020.

Some big-name attendees are standing firm for now, however. The new CEO of one of the largest mobile device manufacturers in the world wrote on Wednesday he planned to be there personally and hoped others would join him in Las Vegas for his Jan. 4 keynote.

“I am greatly honored to be hosting our preshow keynote,” Samsung Electronics CEO Jong-Hee Han posted to the company’s website. 

Despite U.S. President Biden’s own words of caution—he told Americans on Tuesday that they are facing “a critical moment”—his Transportation Secretary Pete Buttigieg is scheduled to give an in-person speech on the future of mobility at the show, which was announced only last Friday.

A spokesman for German premium brand Mercedes-Benz told Fortune that operations chief Markus Schäfer still aims to fly to the CES as well, in order to show off the company’s ultra–long-range electric vehicle, dubbed the EQXX, though the company is monitoring the situation closely. To hedge its bets, a digital premiere of the concept car is scheduled for Jan. 3.

For their part, organizers of the CES say they are actively tracking the emerging news and science around the new Omicron variant and “will adjust their plans and health protocols as necessary.” These already include admittance only for those fully vaccinated. The show told Adweek it remained fully committed to keeping the show in person despite the threat.

“At this point, we’re very much focused on having this show and doing it safely and putting the right protocols in place to ensure that people feel comfortable with it,” Jean Foster, senior vice president of marketing and communications at the CTA, said in an interview.