US coronavirus deaths top 400,000 as variants threaten to take hold

The country’s dizzying pace of new, grim milestones isn’t letting up: the U.S. exceeded 400,000 deaths due to the novel coronavirus on Tuesday, according to data from Johns Hopkins University.

The saddening milestone comes just over a month after the nation surpassed 300,000 virus-related deaths in December, breaking 250,000 deaths less than a month prior.   

"As of this morning, more than 400,000 Americans – a once-unimaginable toll – have died of COVID-19," said Susan R. Bailey, M.D., president of the American Medical Association, in a statement. "One in every 820 people in our country have died during this pandemic – often alone, typically away from family and friends – comforted only by physicians and nurses in layers of PPE."

The incoming Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky warned on Sunday the U.S. is likely to see "dark weeks ahead," with the coronavirus death toll potentially set to hit half a million by mid-February.

The CDC also warned the more transmissible U.K. strain will likely take hold in the U.S. by March.

The strain has already been detected in over a dozen states with nearly 90 cases, though this count doesn’t reflect the true total of cases circulating the country due to under surveillance.

U.K. officials have estimated the variant, called B.1.1.7, spreads about 50% to 70% more easily from person to person, though scientists don’t believe it causes more severe disease and experts say recently approved vaccines will remain effective.

Bailey's statement also called for Americans to continue wearing masks, practicing social distancing, and washing hands amid the rise in the variant spread.

"Today, vaccine distribution is underway, and there is hope on the horizon," Bailey continued. "Vaccines are safe, effective, prevent illness and save lives. Protect yourselves and your loved ones by getting the COVID-19 vaccine when it’s your turn."   

Data from the CDC reports that over 12.2 million Americans have already received the first dose of either Pfizer or Moderna's coronavirus vaccine, with over 31 million doses out to states.

A more contagious strain threatens to further burden already drained resources and health care workers manning the front lines since early last spring. Meanwhile, California health officials on Sunday warned of a separate coronavirus variant, known as L452R, on the rise across the state since last November, and another strain local to Los Angeles, called CAL.20C, has been identified in more than one-third of LA COVID-19 patients. Researchers believe the local strain is driving the county’s continuing surge.

A California pulmonary disease specialist tied the surge to a mutated strain.

"We have a surge in California and I think it’s all because of a new strain," Dr. Imran Sharief, who treats patients in counties across Southern California, wrote to Fox News. "None of my hospitals have any beds available... Every patient I see in the hospital has COVID, there is nothing else."

"I have never seen any disease causing this much severity of sickness," Sharief continued. "In normal days we have on average a 28-bed ICU unit, but now with make-shift ICU unit capacity, [that] has been increased to 60 to 70 beds. I am seeing at least four to 10 cardiac arrests daily. During normal days you see the same number of cardiac arrests in three to four weeks."

While it’s not clear what impact these mutations may have on virus transmissibility or effectiveness of current COVID-19 treatments and vaccines, researchers said the discovery is imperative to ongoing research.

As the mutated strains continue to circulate, data shows the U.S. already ranks fourth worldwide for the most deaths per 100,000 people, among confirmed cases and healthy individuals, at about 122 deaths. Italy, Czechia and the U.K. claim the highest coronavirus-related fatalities per 100,000 population at 137, 136, and 135 deaths, respectively, according to Johns Hopkins University.

The U.S. logged 141,999 new cases, and 1,403 additional deaths Tuesday, contributing to a total exceeding 24 million infections.

Fox News' Alexandria Hein contributed to this report.

Kayla Rivas is a Health reporter and joined Fox News in April 2020.