The Omicron variant of the coronavirus has spread to about one-third of U.S. states, but the Delta version remains the majority of COVID-19 infections as cases rise nationwide, U.S. health officials said on December 5.

Six more U.S. states confirmed infections of the Omicron variant of COVID-19 on December 3, but the Delta strain likely remains a greater threat as winter sets in and Americans gather for the holidays, experts said.

Missouri detected the state’s first case of the Omicron variant of the coronavirus in a resident of St. Louis who had recently traveled domestically, according to the state health department.

Europe crossed 75 million coronavirus cases on December 3, according to a Reuters tally, as the region braces for the new Omicron variant at a time when hospitals in some countries are already strained by the current surge.

A sixth U.S. state – Nebraska – reported the Omicron variant of the coronavirus after detecting six confirmed cases of the highly contagious strain, the state’s health department said on December 3.

A case of the Omicron coronavirus variant was identified in Minnesota on December 2, the U.S. state’s health department said, with the identification coming a day after the United States reported the country’s first case of the new variant.

Austria imposed a lockdown on people unvaccinated against the coronavirus on November 15 as winter approaches and infections rise across Europe, with Germany considering tighter curbs and Britain expanding its booster program to younger adults.

Global Covid-19 cases surpassed 250 million on November 8 as some countries in eastern Europe experience record outbreaks, even as the Delta variant surge eases and many countries resume trade and tourism.

Pfizer, Moderna, and AstraZeneca have been running “dress rehearsals” by adapting their current formulations of Covid-19 vaccines to match present known SARS-CoV-2 variants.

Heading into fall, with the Covid-19 pandemic surging again and researchers tracking new variants, there is plenty of news. BioSpace takes a look, including several research studies suggesting that some people have unusually strong immunity against Covid-19.