The omicron variant is spreading quickly in the U.S. and could trigger a massive wave of coronavirus infections as soon as January, according to new forecasts by the Centers for Disease Control and Prevention.

The coronavirus is surging throughout the U.S. as December holidays approach, particularly in colder climates. Cases of the new omicron variant of the virus are expected to rise next month following family gatherings, White House officials said Wednesday. The latest statistics show that omicron cases double about every two days, according to the CDC.

The proportion of omicron infections in Georgia and surrounding states is lower than other parts of the country. But the potential of twin epidemics — one from the highly transmissible but potentially less severe omicron, and the other from the more severe delta — has public health officials concerned.

Here’s a look at major developments over the past week related to COVID-19.

Omicron cases on the rise

Overall in the U.S., during the week that ended Saturday, Dec. 11, omicron accounted for 2.9 percent of cases across the country, up from 0.4 percent in the previous week, according to agency projections.

In a southern region of eight states that includes Georgia, Alabama, Florida, Kentucky and Mississippi, for the week that ended Dec. 11 omicron cases accounted for under 1% of all the coronavirus cases — 0.79% — according to the CDC.

Other parts of the country are seeing omicron cases accelerate much faster. In the region comprising New York, New Jersey, Puerto Rico and the U.S. Virgin Islands, the percentage of omicron infections had already reached 13.1 percent, according to the latest estimates.

Despite omicron’s rapid rise, it’s delta that still accounts for 99 percent of COVID-19 cases in Georgia.

In a briefing on Tuesday with state and local health officials and representatives of public health labs across the nation, CDC officials warned of two possible scenarios. The first was a tidal wave of infections, both omicron and delta, arriving as soon as next month, just as influenza and other winter respiratory infections peak.

Federal health officials also forecast a second scenario in which a smaller surge of omicron cases occurs in the spring. It was unclear which forecast was more likely.

Though illness caused by omicron seems to be less severe than that caused by delta, if it proves more infectious and spreads further, it could still send greater numbers to emergency rooms and swamp state medical systems.

“My thought is whether it is delta or omicron or whatever comes next we have to get more people vaccinated,” said Dr. Kathleen E. Toomey, commissioner of the Georgia Department of Public Health. “If you are someone who wanted to ‘wait and see’ about the vaccine, please don’t wait any longer. As long as people are not vaccinated, COVID will continue to spread and variants will continue to emerge.”

Toomey and other public health officials also urge adults who are six months out from completing the initial course of vaccination to get their booster shots. Despite reports that the current vaccine may be less effective at preventing infection with the new variant, it still appears to guard against severe illness and deaths, they say.

As of Friday, only six cases of omicron had been detected in Georgia. Officials think the variant is much more widespread in Georgia and across the country because health authorities have the capacity to genetically sequence only a small portion of test results to confirm its presence.

CDC recommends other vaccines over J&J

The CDC recommended that people should get Pfizer and Moderna’s COVID-19 vaccines over the Johnson & Johnson shot, citing the risk of rare blood clots.

The decision adopted a recommendation by an expert panel that effectively discouraged vaccine providers and adults from using Johnson & Johnson’s shot. New data showed that there was a higher risk for the blood clotting condition than previously known. The risk was greatest among women aged 30 to 49, estimated at 1 in 100,000 who had received the company’s shot.

Johnson & Johnson’s vaccine is not being removed from the market. It will remain an option for people who are “unable or unwilling” to receive the more popular shots from Moderna or Pfizer, the agency said.

Emory mandates booster shots for students, staff

Emory University announced Thursday that it will require all employees, faculty and students to get a COVID-19 booster shot within the next month.

Emory, the state’s largest private university, has become one of the biggest schools in Georgia to order booster shots. It has more than 32,000 employees and about 15,000 students.

President Gregory Fenves said in a letter the university is requiring the shots because of the increased spread of COVID-19 nationwide and the emerging omicron variant.

More than two dozen colleges and universities nationwide have required booster shots, according to the Chronicle of Higher Education. Most are private universities located in the northeast, such as Boston, Bucknell and New York universities.

-Staff writers J. Scott Trubey and Eric Stirgus contributed to this report. The New York Times and The Associated Press also contributed to this report.