Omicron variants BQ.1 and BQ.1.1 make up nearly half of new COVID cases. What to know.

• BA.5 has lost its grip on the US, accounting for only 29.7% of new COVID cases as of mid-November.
• BQ.1 and BQ.1.1 are taking over. First identified in September, the two variants make up nearly half of new infections.
• Not much is known about the newest strains, but experts say the bivalent boosters should offer some protection.

Vaccine developer Moderna shared trial data this week showing its new COVID-19 bivalent booster is effective at protecting against the BA.4 and BA.5 omicron subvariants.

But the good news may have come too little, too late.

BA.5 — once the dominant variant during the summer months — now makes up less than a third of new COVID-19 cases heading into the holidays. Edging it out are sublineages BQ.1 and BQ.1.1, which make up nearly half of new cases and appear to be gaining ground.

Although not much is known about the newest strains, experts say the bivalent booster should offer some protection. Here’s what you should know.

Latest COVID-19 news:

• Combination vaccine: Researchers working to create flu-COVID shot
• Bivalent boosters: Which COVID shot should I get, and when? 
• Pfizer-BioNTech: 30 day data shows bivalent booster as safe as earlier shots

BA.5 

Parental strain: The original omicron strain (BA.1) 

Prevalence: An estimated 29.7% of new cases this week 

What to know: BA.5 was detected in the U.S. at the end of April, experts say, with cases first appearing in the Northeast, then spreading to Southern, Midwestern and Western states. The subvariant quickly become the dominant strain during summer, making up more than 99% of new cases by August. The COVID-19 bivalent boosters were designed to target BA.4, and its twin, BA.4.

Stay up-to-date on COVID news: Sign up for the Coronavirus Watch newsletter

BQ.1 and BQ.1.1 

Parental strain: BA.5

Prevalence: 20.1% and 24.1%, respectively 

What to know: BQ.1 and BQ.1.1, the newest strains, have gained the attention of top health experts due to its rate of increase since it was first identified in early September. 

Dr. Peter Hotez, a pediatrician and dean of the National School of Tropical Medicine at Baylor College of Medicine Houston, called BQ.1.1 the “most likely candidate” to drive a new COVID-19 wave, if that were to happen in the coming months.

Mutation: The strains are descendent of the BA.5 omicron subvariant, but contain a couple of key mutations to the spike protein that health experts speculate may give it an advantage. One such mutation, R346T, has been seen in previous variants and is thought to be associated with immune evasion, said Andrew Pekosz, a virologist and professor at Johns Hopkins Bloomberg School of Public Health.

BF.7 

Parental strain: BA.5

Prevalence: An estimated 5.3% of new cases this week

What to know: "It is also picked up a few mutations we know will evade vaccine induced immunity so we’re keeping an eye on it to see how much of that immunity it will evade," Pekosz said. 

Mutation: BF.7 is another descendent of BA.5 with the R346T mutation. 

Bivalent boosters vs. new variants

Moderna: This week, the company shared trial results from over 500 participants ages 19 to 89 that showed:

• Neutralizing antibodies against BA.5 increased 15-fold from pre-booster levels.
• They also increased 5-fold in participants with a previous COVID-19 infection and 6-fold higher for those without.
• Data was consistent between older and younger participants.

The Cambridge-based company said its bivalent shot also showed “robust neutralizing activity” against the BQ.1.1 variant, suggesting it may offer some protection against the newest strains edging out BA.5.

It’s “confirming that updated vaccines have the potential to offer protection as the virus continues to evolve rapidly to escape our immunity,” said Moderna’s chief executive officer Stéphane Bancel.

Pfizer-BioNTech: The companies have yet to share data on how its bivalent booster performs against the BQ.1 and BQ.1.1 variants but they released results in early November that showed:

• At 30 days, neutralizing antibodies against the BA.4 and BA.5 variants increased 13-fold in adults 55 and older and increased nearly 10-fold in younger adults.
• By contrast, people who received a shot targeted solely at the original virus saw a threefold  increase in neutralizing antibodies against those variants. 

Contributing: Karen Weintraub, USA TODAY. Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT. 

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.