CDC Announces New Strain of Omicron in US

A new version of Omicron has taken root in the US, according to the latest data from the Centers for Disease Control and Prevention. The omicron sub-variant, called XBB.1.5, has raised concerns about a new potential wave of Covid cases after a busy holiday season.

On Friday, the CDC predicted that about 40% of confirmed Covid cases in the US are due to the XBB.1.5 strain, up from 20% a week ago. In the northeast, about 75% of confirmed cases are reported to be XBB.1.5.

It’s not yet clear where this version of omicron came from, but it seems to be spreading quickly here. There is no indication that it causes more severe disease than any other omicron virus, Dr. Barbara Mahon, director of the CDC’s Coronavirus and Other Respiratory Viruses Division, told NBC News.

While overall Covid hospitalizations are rising across the country, areas like the Northeast, which has seen high levels of the new variant, are not seeing a disproportionate increase in hospitalizations, Mahon said.

“We see that the number of hospitalizations in the whole country is increasing,” she said. “They don’t seem to be scoring more in areas that have more XBB.1.5.”

Over a seven-day average, daily Covid hospitalizations reached 42,140 on Friday, up 4.2% from two weeks earlier, according to NBC News calculations. The seven-day average of daily ICU admissions also rose to 5,125 per day, more than 9% more than two weeks ago.

Much is still unknown about the latter subvariant, Mahon said, including whether it is more contagious than other forms of omicrons.

Other scientists are concerned that XB.1.5 is doing even better against the antibodies we created from Covid vaccines and previous infection from the many different types of omicrons that have proliferated since last December, including the original BA.1 and later. Sub-options BQ.1.1 and BQ.1.

XBB.1.5 is a relative of the omicron XBB variant, which is a recombinant of the omicron sub-variants BA.2.10.1 and BA.2.75.

Together, XBB and XBB.1.5 account for 44% of cases in the US, crowding out other versions of Omicron.

According to the World Health Organization, XBB has been found in at least 70 countries and caused a spike in infections in parts of Asia in October, including India and Singapore.

Laboratory studies have shown that XBB is able to evade antibodies from previous Covid infections or vaccinations, meaning that exposure to the virus will mean someone is more likely to get sick or re-infected and show symptoms.

“Clearly, CVV has the ability to evade the immune system,” said Dr. Isaac Bogoch, an infectious disease physician and epidemiologist at the University of Toronto. “This has been demonstrated both in laboratory studies and clinically in cases and hospitalizations.”

Given the high level of herd immunity in the US — whether through infection, vaccination, or both — Bogoch and others are hopeful that, even if the number of cases starts to rise significantly, there will not be a spike in hospitalizations or deaths, as was the case in previous waves. .

Antibody studies don’t tell the whole story. Evidence suggests that other parts of the immune system can protect against the virus, and Covid vaccines should remain effective in preventing severe illness and death from the virus.

“We can certainly have a wave, but it is far less likely to be as lethal or overwhelming to the healthcare system than earlier waves before we had this degree of hybrid immunity,” Bogoch said.

Do Covid vaccines work against XBB.1.5?

As encouraging signs, Rick Bright, an American immunologist and former director of the Biomedical Advanced Research and Development Administration, or BARDA, pointed to Singapore’s experience with XBB.

There was a spike in cases, but “we haven’t seen a corresponding significant spike in hospitalizations and deaths,” Bright said.

“We think this is because more people in Singapore have been vaccinated with the latest vaccines and boosters,” he said.

Unfortunately, this can be a problem in the US.

People aged 65 and over are most vulnerable to any form of the Covid virus. However, according to the most recent data from the CDC, only 37.5% of this age group received the most recent booster dose of omicron.

Experts agree that the most important thing is to get re-vaccinated with new bivalent vaccines to strengthen your immune system against new variants.

“We’re not in 2020, but people still need to take this seriously and protect themselves,” Mahon said, adding that getting a bivalent booster is especially important for people over 65, a high-risk group who have seen fairly low consumption. boosters lately.

A study published last week in the New England Journal of Medicine found that Moderna and Pfizer-BioNTech’s new Covid boosters boost antibody responses to many Omicron sub-options, including the XBB variant.

While the new booster, called bivalent because it targets the omicron BA.4 and BA.5 strains as well as the parent coronavirus, is not perfect, it does offer additional protection over what was found in the parent or monovalent boosters previously available. . said Mehul Sutar, assistant professor of the Emory Vaccine Center at Emory University and author of the report.

“With monovalent boosters, your neutralizing antibodies aren’t as effective against variants, but bivalent boosters ensure they’re a bit better,” he said. “It’s not mind blowing, but it’s better, which shows that bivalent boosters are working as they should.”