The Covid omicron XBB.1.5 variant is rapidly becoming dominant in the U.S. because it is highly immune evasive and appears more effective at binding to cells than related subvariants, scientists say.

XBB.1.5 now represents about 41% of new cases nationwide in the U.S., nearly doubling in prevalence over the past week, according to the data published Friday by the Centers for Disease Control and Prevention. The subvariant more than doubled as a share of cases every week through Dec. 24. In the past week, it nearly doubled from 21.7% prevalence.

Focus on these new names: BQ1 and BQ1.1.  They are two of the hundreds of subvariants of the Omicron variant of the coronavirus behind COVID-19 that the World Health Organization is tracking.  

These subvariants have shown up in Nigeria, the United Kingdom, Japan, Canada, France, Belgium, New Zealand, Denmark and Italy.  And serious COVID-19 cases are rising around the world, just not in the U.S. yet. But we have been down this road before and we know, by now, where it is likely to lead.

The U.S. should prepare for a spike in COVID cases this winter as more people gather indoors and infections already begin to rise in Europe, White House COVID-19 Response Coordinator Ashish Jha says.

The warning echoes that of some other experts who anticipate a rise in cases in the coming months, while other modelling suggests that infections will recede in the near future.

A new coronavirus variant BQ.1 and its sibling BQ1.1. are steadily accounting for more infections in the United States, spurring some concern that it may help fuel a resurgence in cases this winter.

BQ.1 and BQ1.1., which both descend from BA.5, an omicron subvariant that accounts for over 67% of COVID-19 cases in the U.S., now make up roughly 11% of infections and are closing in on becoming the second-most dominant variant in the U.S., a rate at which Biden chief medical adviser Dr. Anthony Fauci said is "pretty troublesome."

The Centers for Disease Control and Prevention on Wednesday recommended a COVID-19 vaccine booster shot for children as young as 5, aimed at the Omicron variant, hours after the Food and Drug Administration authorized the shot.

The big picture: The announcement comes as the White House continues to monitor a rise in the COVID-19 subvariants emerging and evolving throughout the world.

Children as young as five are to be offered the bivalent Covid booster vaccine ahead of the winter.

The  Centers for Disease Control and Prevention (CDC) has recommended five to 11-year-olds get a single dose of Pfizer's updated shot.

Children aged six and above can get Moderna's bivalent booster. Both new vaccines offer better protection against the new Omicron variants than previous jabs.

Officials are now 'encouraging' parents to get their children vaccinated before schools go back from the fall break.

The US Centers for Disease Control and Prevention signed off Wednesday on the use of updated Covid-19 boosters for children as young as 5. Earlier in the day, the US Food and Drug Administration expanded the shots’ emergency use authorization to include this age group.

The moves mean children and teens can get the boosters from Moderna and Pfizer/BioNTech as long as they’re at least two months past their primary vaccine series or last booster dose.

Earlier this month, the U.S. began administering the first COVID-19 booster vaccines that have been updated to better match the latest circulating coronavirus strains.

Many scientists expect the revised boosters will be more effective than their predecessors, but whether that’s the case and to what degree remains unknown.

The U.S. Food and Drug Administration (FDA) announced Wednesday that it has authorized updated coronavirus booster shots targeting the highly-contagious omicron variant.

"Today, the U.S. Food and Drug Administration amended the emergency use authorizations (EUAs) of the Moderna COVID-19 Vaccine and the Pfizer-BioNTech COVID-19 Vaccine to authorize bivalent formulations of the vaccines for use as a single booster dose at least two months following primary or booster vaccination," it said in a statement.

The Food and Drug Administration on Wednesday authorized new Covid booster shots from Moderna and Pfizer that more closely match the strains of the coronavirus that are currently circulating in the U.S.

Pfizer’s booster, made with partner BioNTech, is being authorized for people as young as 12 years old. The Moderna booster is being authorized for people ages 18 and up.