The coronavirus numbers in the U.S. continue to surge as the country surpassed 400,000 deaths.

“Deaths certainly did not take a holiday,” Dr. Michael Saag, associate dean for global health at the University of Alabama at Birmingham, said on Yahoo Finance Live (video above). “In fact, the holidays are causing a lot of deaths.”

Despite urgent calls not to travel, more than 7 million people were screened at TSA checkpoints during the week of Christmas. Another wave will likely follow in coming weeks as a newer, most contagious coronavirus strain becomes dominant in the U.S.

President-elect Biden’s nominee to lead the Centers for Disease Control and Prevention (CDC), Dr. Rochelle Waleksnky, predicted the U.S. will cross the 500,000 death count by mid-February.

“We still yet haven’t seen the ramifications of what happened from the holiday travel, from holiday gathering in terms of high rates of hospitalizations and the deaths thereafter,” she told CBS. “So, yes, I think we still have some dark weeks ahead.”

‘Never seen this much death before’

There have been over 24 million coronavirus cases in the U.S. so far, roughly 25% of the world’s total confirmed case count.

Some areas of the U.S. are facing an insurmountable number of cases — over the weekend, Los Angeles became the first county to hit 1 million cases, roughly ? of the state’s total.

Public health officials from LA County attributed much of it to the region lifting restrictions on business and in-person gatherings back in November, right before the Thanksgiving holiday.

"We've never seen this much death before," a nurse for St. John’s Regional Medical Center told the Ventura County Star. "I’ve been in health care for 22 years, and I’ve never been scared. Right now, I am ... I fear for my children."

Though he works mostly in the outpatient setting, Saag said his situation is “on the verge of being overwhelming.”

The vaccine race

Another issue are the mutant strains of the virus popping up around the globe.

These variants have been shown to be more transmissible than the original strain of the virus, meaning that social distancing and other public health guidelines are more crucial to follow than ever before.

“The variant is in the country,” Saag said. “It’s not even clear if it came from outside, because there are pathways when these viruses replicate that are just kind of common. So it’s possible that a variant emerged in Great Britain and simultaneously in Colorado. That’s possible. But nonetheless, I think whatever we can do to keep the variants at bay while we vaccinate people is really essential.”

Saag described it as like “a cat-and-mouse game” that the medical community has to stay in front of.

“That means vaccinating a lot of folks before these variants have a chance to mutate to a point where maybe the vaccines won’t work,” he said. “So we need all hands on deck in any way we can.”

As of Jan. 19, over 31 million vaccines have been distributed so far, but only 15.7 million people in the U.S. have actually been inoculated. In order for the country to reach herd immunity, between 80-90% of the public needs to be vaccinated.

The incoming Biden administration’s goal is to vaccinate 1 million Americans a day throughout the first 100 days of Biden’s presidency. But Saag said he thinks it can even get to 2 million daily vaccinations.

“That’d be great,” he said. “So maybe they’re setting a bar for lower expectations. And if we exceed it, fantastic. That’d be great. Our goal is to get as many Americans vaccinated as soon as possible. That’s how we bring the end to this.”

Adriana is a reporter and editor covering politics and health care policy for Yahoo Finance. Follow her on Twitter @adrianambells.

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