By Akshay Syal, MD -
NBC News
A new version of omicron has taken hold in the United States, according to the latest data from the Centers for Disease Control and Prevention (CDC).
The subvariant, called XBB.1.5, has raised concerns about another possible wave of coronavirus cases after the busy holiday travel season.
The CDC projected Friday that about
40% of confirmed COVID-19 cases in the country are caused by 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.
[The wave of infections in China raises fears of a new mutant version of COVID-19]
It's still not clear where this version of omicron came from, but it seems to be spreading fast.
There is no indication that it causes more severe illness than any other omicron virus, Dr. Barbara Mahon, director of the CDC's Division of Coronavirus and Other Respiratory Viruses, told NBC News.
People walk past a COVID-19 testing site in New York City, December 12, 2022.EDUARDO MUNOZ/REUTERS
While
overall coronavirus hospitalizations are rising across the country
, areas like the Northeast that have seen high levels of the new variant have not seen a disproportionate rise, Mahon said.
“We are seeing that hospitalizations have gone up overall across the country,” he explained, “without it looking like they are affecting areas that have more XBB.1.5 more.”
There were a daily average of 42,140 hospitalizations
in the seven-day count on Friday
, up 4.2% from the previous two weeks, according to a tally by NBC News.
The seven-day average of daily intensive care unit admissions also increased to 5,125 per day, an increase of more than 9% compared to two weeks ago.
Much is still unknown about the latter subvariant, including whether it is more contagious than other forms of omicron, Mahon said.
Other scientists worry that XB.1.5 may be better able to get around the antibodies we've developed from coronavirus vaccines and from previous infections of the many different types of omicron that have spread since last December, including BA. 1 original and the most recent sub-variants, BQ.1.1 and BQ.1.
The XBB.1.5 is a relative of the omicron variant XBB
, which is a recombinant of the omicron subvariants BA.2.10.1 and BA.2.75.
Combined, XBB and XBB.1.5 account for 44% of the cases in the US, displacing other versions of omicron.
XBB has been found in at least 70 countries
, according to the World Health Organization, and has led to surges in infections in some parts of Asia, including India and Singapore, in October.
[US hospitals report rise in serious strep A infections in children after 15 deaths in UK]
Studies done in the lab have found that XBB is able to evade antibodies from previous infections or vaccinations, which means that being exposed to the virus would mean someone is more likely to get sick or reinfected and show symptoms.
“It is clear that XBB has characteristics that allow it to evade the immune response,” said Dr. Isaach Bogoch, an infectious disease physician and epidemiologist at the University of Toronto.
"That has been shown both in laboratory studies and seen clinically in cases and hospitalizations," he said.
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Given the high level of immunity in the country's population, whether from infection, vaccination, or both, Bogoch and others hope that even if cases begin to rise significantly, there will not be a dramatic increase in hospitalizations or deaths as seen in previous waves.
Antibody studies do not give a complete idea of what is happening.
Other parts of the immune system can protect against the virus, and COVID-19 vaccines should remain effective in preventing severe illness and death from the virus, study results suggest.
"We certainly could have a wave, but
it's much less likely to be as deadly or overwhelming for the health care system compared to previous waves
when we didn't have the level of hybrid immunity that we have now," Bogoch said.
Do XBB.1.5 vaccines work?
As encouraging signs, Rick Bright, an American immunologist and former director of the Biomedical Advanced Research and Development Authority, or BARDA, pointed to Singapore's experience with XBB.
There was an increase in cases, but "we did not see a significant increase in hospitalizations and deaths as a correlation," Bright said.
“We think it is because a large population of people in Singapore have been vaccinated with the latest vaccines and boosters,” he said.
Unfortunately, that could be a problem in the US People over the age of 65 are the most vulnerable to any form of the coronavirus.
However, only 37.5% of that age group have received the updated omicron booster, according to the most recent data from the CDC.
Experts agree that
the most important thing is to receive a booster dose with bivalent vaccines
to bolster your immune system against the newer subvariants.
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"It's not 2020, but people still need to take this seriously and protect themselves," Mahon said, adding that getting the up-to-date vaccine is especially important for people older than 65, a high-risk group in which it has been recently seen a low booster vaccination rate.
A study published last week in the New England Journal of Medicine found that new boosters from Moderna and Pfizer-BioNTech improve antibody responses to many Omicron subvariants, 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 original coronavirus, isn't perfect, it does offer additional protection than was seen in previously available original or monovalent boosters, said Mehul Suthar, an associate professor at the Emory Vaccine Center at Emory University and an author of the report.
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"With the monovalent boosters, your neutralizing antibodies just aren't as potent against the variants, but the bivalent booster makes sure it's a little better," he said.
“
It's not amazing, but it's better,
indicating that the bivalent boosters are working as they should,” he noted.
The new XBB.1.5 variant was not included in the report, but Suthar predicts that its evasive immune properties will be in a similar range to XBB.
He hopes that the bivalent boost will also strengthen protection against the latest version.
