Delta variant still causes almost all US virus cases. Will omicron add misery or fade away?

While all eyes are on the new and little-understood omicron variant, the delta form of the coronavirus isn’t finished wreaking havoc in the U.S., sending record numbers of patients to the hospital in the Midwest and New England.

“Omicron is a spark that’s on the horizon. Delta variant is the fire that’s here today,” said Dr. Nirav Shah, director of the state Center for Disease Control and Prevention in Maine, where an unprecedented 334 people were in the hospital with COVID-19 as of midweek.

The U.S. recorded its first known omicron infection on Wednesday, in a fully vaccinated person who had returned to California from South Africa, where the variant was first identified just over a week ago.

But there is much that is unknown about omicron, including whether it is more contagious than previous versions, makes people sicker or more easily thwarts the vaccine or breaks through the immunity that people get from a bout of COVID-19.

For now, the extra-contagious delta variant accounts for practically all cases in the U.S. and continues to inflict misery at a time when many hospitals are struggling with shortages of nurses and a backlog of patients undergoing procedures that had been put off early in the pandemic.

Two more U.S. cases were confirmed Thursday. One was in a Colorado woman who had recently traveled to southern Africa. The other was in a Minnesota man who had attended an anime convention in New York City just before Thanksgiving that drew an estimated 50,000 people. Minnesota officials said he had no history of international travel. That would suggest the variant has begun to spread within the U.S.

Governments around the world are weighing new measures for populations tired of hearing about restrictions and vaccines as the coronavirus delta variant of COVID-19 pushes up cases in Europe and fears grow over the omicron variant.