Health and Science

Covid cases on the rise again, but it's still delta, not omicron, driving the surge

Erika Edwards
A medical worker extracts a specimen from a vial with a nasal swab Covid-19 test at the Dignity Health-GoHealth Urgent Care testing site in the international terminal at San Francisco International Airport (SFO) in San Francisco, California, U.S., on Thursday, Dec. 2, 2021.
David Paul Morris | Bloomberg | Getty Images

Even as more and more states report their first cases of the omicron variant, it's still the super contagious delta variant that's driving nearly all new Covid-19 cases in the United States.

What's more, it appears cases are once again rising after Thanksgiving.

Dr. Michael Saag, an associate dean for global health at the University of Alabama at Birmingham, has seen a "notable increase" of Covid patients in need of monoclonal antibody treatments over the past 24 hours.

"Think about it," Saag said. "Somebody gets exposed and infected on Thursday or Friday of last week. Then it takes two or three days for incubation."

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By all accounts, the driver of current Covid cases across the United States remains the delta variant of the coronavirus, not omicron.

"I know that the news is focused on omicron, but we should remember that 99.9 percent of cases in the country right now are from the delta variant," Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said Friday during a news briefing. The majority of cases, she said, are among people who remain unvaccinated.

Walensky reported that the current seven-day average of new Covid cases is about 86,400 per day. On this day one month ago, according to CDC data, the seven-day average was 70,000 cases per day.

Delta is certainly behind that increase. How omicron may drive cases moving forward remains a mystery.

"It's going to take a while for us to know what the impact is going to be globally for people who are infected with omicron," Dr. Anthony Fauci, chief medical adviser to the Biden administration, said during Friday's briefing.

Dr. Mary Bassett, health commissioner for the New York State Department of Health, said her team has ramped up genetic sequencing to detect and study the omicron variant.

"We urge the public not to panic, as we are still learning more about this variant and are prepared to handle it," Bassett said during a news conference Thursday. So far, at least five cases have been identified in New York. Omicron has also been detected in California, Colorado, Hawaii, Minnesota, Missouri and Nebraska.

Will omicron overtake delta as the predominant variant? No one knows — yet.

"What the virus wants is to infect more people," said Matthew Binnicker, an infectious disease expert at the Mayo Clinic in Rochester, Minnesota.

He explained that viruses mutate because they want to live, spreading more easily from person to person.

"That's why we saw delta take over. It out-competed all of the other variants of SARS-CoV-2 in the world," Binnicker said. "It became king of the hill."

Meanwhile, doctors are preparing for what they fear will be yet another winter surge of Covid-19, attributed to more holiday gatherings.

"We have Christmas and New Year's coming up," Saag said. "Wash, rinse, repeat."