Sure enough, just as the holiday COVID case surge seemed to be fading, new variants are spreading quickly across the U.S. and are expected to gain ground here too.
One omicron variant in particular — XBB.1.5 — has caught the attention of infectious-disease experts, as it is new and seems to be spreading quickly, even after most of us already have had some combination of COVID infections, vaccines and boosters. So what does that tell us?
“We know it’s very immune-evasive, much more than all of its cousins, and that’s cause for concern,” said Dr. John Swartzberg, professor emeritus of the University of California-Berkeley’s school of public health division of infectious diseases and vaccinology.
The good news: The new variant doesn’t seem to be causing more serious illness or deaths, he said. “There’s nothing we’ve seen thus far that it’s more virulent than the other variants.”
Here’s what else we know about XBB.1.5 and other omicron variants:
Q What is XBB.1.5 and where did it come from?
A It’s similar to the XBB variant that spread rapidly through Singapore last year, then quickly disappeared in the highly immunized country, Swartzberg said. XBB.1.5’s origins are unknown, but Swartzberg said it may well have started in the U.S. It is dominant in the Northeast but only 8% of cases in California and other Southwest states.
Q What about its spread is alarming?
A XBB.1.5 was hardly on the radar at Thanksgiving. Then initial CDC forecasts of variant proportions suggested it multiplied from 4% to more than 40% of cases nationally in just a few weeks, which White House COVID-19 Response Coordinator Dr. Ashish K. Jha this week called “a stunning increase.”
Updated CDC estimates, however, show XBB.1.5 has grown from 2% on Dec. 3 to 28% Friday. The variants known as BQ.1 and BQ.1.1 have remained dominant since November, growing from a combined 54% on Dec. 3 to 62% Friday.
Q What’s happening with COVID cases, hospitalizations and deaths in the U.S. and California?
A For the U.S., California and Bay Area, cases peaked between Thanksgiving and Christmas and never came close to the heights reached the past two winters. Hospitalizations are rising nationally but seem to have peaked in California. Deaths have plateaued at far lower levels than seen in past winters.
Q So what’s there to worry about?
A COVID is still claiming 350 to 400 lives a day in the U.S. and a daily average of more than 30 Californians. That’s higher than the 240 deaths a day seen across the U.S. at the pandemic’s low point in the early summer of 2021. At the current rate, the U.S. would lose 128,000-146,000 people a year to COVID.
By comparison, influenza killed an estimated 12,000-52,000 people a year over nine seasons from 2010 to 2019. The rate of annual U.S. automobile fatalities is around 39,000-43,000, in line with average annual flu deaths.
Q Is XBB.1.5 the same variant that’s been ripping through China?
A No. Swartzberg said China is primarily stricken with the omicron variant BF.7, which accounts for only about 2% of U.S. cases.
Q If I had a COVID infection, vaccine or booster, am I protected?
A Jha said that if you had COVID before July or your last vaccine was before the updated omicron bivalent booster in September, “your protection against an XBB.1.5 infection is probably not that great.” Currently only about 15% of people in the U.S. have had the updated booster.
Q Why is XBB.1.5 spreading so fast?
A Michael Daignault, an emergency physician at Providence St. Joseph Medical Center in Los Angeles, said XBB and XBB.1.5 are subvariants of BA.2, with some key mutations that make it easier to infect our cells. “It has become the most ‘fit’ new variant and comprises a majority of cases now,” Daignault said.
Q Why isn’t it more dangerous?
A That immune-evasiveness enables the variant to avoid the antibodies that form the first line of defense against infectious diseases, but the T cells and B cells that help the body tamp down infections continue to provide protection against severe disease. Also, Daignault said the omicron variant family is not as efficient in getting into our lung tissue, compared to earlier variants such as delta that proved more virulent.
Q What about BQ.1 and BQ.1.1?
A Those two variants hail from the BA.5 omicron variant that dominated most of last year, Daignault said. Since that is what many people were infected with last year, and the updated boosters are tailored to BA.5, people’s immunity should remain fairly protective against them.
Q Why are hospitals still reporting so many COVID patients?
A Daignault noted that hospital practices of screening all patients for COVID result in many positive tests for patients who sought treatment for other ailments and had few if any COVID symptoms. “I have not had a patient in the ER with severe COVID illness — hypoxia, pneumonia — since last January 2022,” Daignault said.
But the XBB.1.5 cases are just taking off now, and Jha said “we don’t know” yet if XBB.1.5 is more dangerous than earlier variants.
Q Are the BA.4 and BA.5 omicron variants still out there, and do the vaccines work against XBB.1.5?
A BA.4 is history and BA.5 only accounts for about 4% of cases, down from 80% a year ago. Jha said this week “we will soon have more data on how well vaccines neutralize XBB.1.5, but right now, for folks without a very recent infection or a bivalent vaccine, you likely have very little protection against infection, and for older folks, diminishing protection against serious illness.”
Q Do COVID tests and treatments still work to detect and fight XBB.1.5?
A Jha said “all the evidence says that tests “should work just fine” and that treatments such as Paxlovid and Molnupiravir “should work fine based on what we know.”
Q If you were recently infected or already had the latest booster, what more can you do?
A Swartzberg said the combination of vaccines, boosters and infections have produced a robust “immunity wall” that has blunted the impact of the virus. Though more contagious, the virus is becoming less deadly — California COVID cases have risen each year since 2020, but deaths declined last year. That said, deaths are still too high, and the elderly remain most vulnerable, but masks and tests can help avoid spreading the virus.