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- A retrospective analysis of clinical features of patients hospitalized with SARS-CoV-2 Omicron variants BA.1 and BA.2 | Scientific Reports Nature.com
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BQ, XBB omicron subvariants pose serious threat to boosters
Evusheld injection, a new COVID treatment that people can take before becoming symptomatic, in Chicago on Friday, Feb. 4, 2022.
Chris Sweda | Tribune News Service | Getty Images
The omicron subvariants that have become dominant in recent months present a serious threat to the effectiveness of the new boosters, render antibody treatments ineffective and could cause a surge of breakthrough infections, according to a new study.
The BQ.1, BQ.1.1, XBB and XBB.1 omicron subvariants are the most immune evasive variants of Covid-19 to date, according to scientists affiliated with Columbia University and the University of Michigan. These variants, taken together, are causing 72% of new infections in the U.S. right now, according to data from the Centers for Disease Control and Prevention.
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The scientists, in a study published online Tuesday in the peer-reviewed journal Cell, found that these subvariants are “barely susceptible to neutralization” by the vaccines, including the new omicron boosters. The immune response of people who were vaccinated and had breakthrough infections with prior omicron variants was also weaker against the subvariants.
“Together, our findings indicate that BQ and XBB subvariants present serious threats to current COVID-19 vaccines, render inactive all authorized antibodies, and may have gained dominance in the population because of their advantage in evading antibodies,” the scientists wrote.
Although these subvariants are more likely to cause breakthrough infections, the vaccines have been shown to remain effective at preventing hospitalization and severe disease from omicron, the scientists wrote.
The study examined blood samples from people who received three or four shots of the original vaccines, those who received the new omicron boosters after three shots of the original vaccines, and individuals vaccinated with the original shots who also had breakthrough infections from the BA.2 or BA.5 subvariants.
For people who received the omicron boosters, antibodies that block infection were 24 times lower against BQ.1, 41 times lower against BQ.1.1, 66 times lower against XBB and 85 times lower against XBB.1 compared to their performance against the ancestral strain that emerged in Wuhan, China in 2019.
However, people who received the omicron boosters had modestly higher antibody levels against all of these subvariants compared with people who received three or four shots of the original vaccines, according to the study.
People who were vaccinated and had breakthrough infections had the highest antibody levels of any group in the study, though neutralization was also much lower against the subvariants than the ancestral strain.
The subvariants have evolved away from previous versions of omicron in dramatic fashion. BQ.1.1, for example, is about as different from omicron BA.5 as the latter subvariant is from ancestral Covid strain, according to the study.
“Therefore, it is alarming that these newly emerged subvariants could further compromise the efficacy of current COVID-19 vaccines and result in a surge of breakthrough infections, as well as re-infections,” the scientists wrote.
XBB.1, however, presents the biggest challenge. It is about 49 times more resistant to antibody neutralization than the BA.5 subvariant, according to the study. XBB.1, fortunately, is currently causing no more than 1% of infections in the U.S., according to CDC data.
BQ.1.1 and BQ.1 represent 37% and 31% of new infections respectively, while XBB is causing 4.7% of new infections, according to CDC data.
Antibodies ineffective
Key antibody drugs, Evusheld and bebtelovimab, were “completely inactive” against the new subvariants, according to the study. These antibodies are used primarily by people with weak immune systems.
Evusheld is an antibody cocktail used to prevent Covid in people with weak immune systems who don’t respond strongly to the vaccines. Bebtelovimab is used to prevent Covid from progressing to severe disease in organ transplant patients and other individuals who cannot take other treatments.
“This poses a serious problem for millions of immunocompromised individuals who do not respond robustly to COVID-19 vaccines,” the scientists wrote. “The urgent need to develop active monoclonal antibodies for clinical use is obvious.”
The FDA has already pulled its authorization of bebtelovimab nationwide because it is no longer effective against the dominant omicron variants in the U.S. Evusheld remains authorized as the only option for pre-exposure prophylaxis.
New Covid infections increased by about 50% to 459,000 for the week ending Dec. 7, according to CDC data. Covid deaths increased 61% to nearly 3,000 during the same week. Hospital admissions have plateaued at 4,700 per day on average after rising in November, according to the data.
White House chief medical advisor Dr. Anthony Fauci, in a press briefing last month, said U.S. health officials are hoping there’s enough immunity in the population from vaccination, infection or both to prevent the massive surge of infections and hospitalizations the U.S. suffered last winter when omicron first arrived.
Flu overtakes COVID-19 in U.S. as primary respiratory illness
More people are falling seriously ill with the flu in the United States than with COVID-19, a demonstration of this year’s severe influenza season – but also of the waning seriousness of a pandemic that once brought the world to its knees.
Figures collected by the U.S. Centers for Disease Control and Prevention show that the weekly rate of hospitalizations for the flu has reached 5.9 per 100,000 people, a level not seen at this time of year in more than a decade.
For COVID-19, however, the rate has fallen to 4.3 per 100,000, far below the January high of 34.8. The figures for both the flu and COVID-19 are for the week ending Dec. 3, the most recent data available.
The dwindling severity of COVID-19 comes after President Joe Biden said in September that “the pandemic is over.”
Numbers of COVID-19 cases in the U.S. have been on the rise in recent weeks, with nearly 5,000 daily hospital admissions. But for COVID-19 to qualify as a pandemic virus, “the threshold would be that it is still causing hospitals to be completely disrupted,” said Amesh Adalja, an infectious disease specialist at Johns Hopkins Center for Health Security. “And I don’t think COVID-19 has been doing that for some time.”
We have “ceased seeing hospitals being under siege by the virus,” he added.
COVID-19 measures brought the flu to standstill. Why experts say the coming season is unpredictable
Although COVID-19 is not as threatening as it once was, public health officials across the U.S. have expressed wariness of rising case counts, particularly as part of a “tri-demic” of COVID-19, respiratory syncytial virus (or RSV) and the flu. Parts of the U.S. have warned about localized shortages of drugs to treat sick patients, including some antibiotics and pain relievers.
In California, some school districts and counties – including Los Angeles – have warned they may reinstitute mask mandates if the number of hospitalized COVID-19 patients continues to increase. Nassau Community College in Uniondale, N.Y., plans to bring back a mask mandate next week.
Between influenza, RSV, rhinovirus and parainfluenza viruses, “you have six or seven different pathogens” of concern in the U.S. at the moment, said Peter Hotez, co-director of the Texas Children’s Hospital Center for Vaccine Development.
“And masks help with that as well,” he said.
Epidemiologists in the U.S. continue to track the spread of new COVID-19 variants, including the XBB recombinant variant that has spread widely in places like Singapore, and has begun to become more visible in the U.S. Scientists say XBB is of concern because it seems to be more resistant to vaccines, although infected patients tend to experience relatively mild symptoms.
But overall, “it’s hard to say just yet whether this is going to be a major, significant wave or not,” Dr. Hotez said.
Unlike the past two winters, “we haven’t seen one subvariant really dominate,” he added.
Europe, whose waves of COVID-19 have typically preceded those in the U.S., has also seen a more muted winter wave this year.
“So it says to me that maybe this won’t be as bad as the past ones,” Dr. Hotez said.
That said, he added, “we don’t have a lot of experience with this new situation, where you have multiple variants within this wave.”
The decreasing severity of COVID-19 is a result of broad exposure to the virus and effective ways to treat it. A large percentage of the world’s population has now either been infected by COVID-19 or immunized against it.
In November, the World Health Organization reported a 90-per-cent drop in COVID-19 deaths, compared to nine months before. More than 70 per cent of the world’s population has now been vaccinated in some form.
New variants emerging today “are much easier to handle because of the immunity in the population,” Dr. Adalja said.
Treatments like Paxlovid, an antiviral medication authorized for use in the U.S. last year, have also proven effective. The Centers for Disease Control has reported that adults who take the oral medication are 50 per cent less likely to enter hospital with COVID-19.
Yet all of that comes as scant consolation to health care providers, for whom COVID-19 infections matter less than the total number of incoming patients, which has in some places reached new heights.
One hospital in Pomona, Calif. recently handled a record 382 emergency room visits in a single day and has set up a flu clinic in an auditorium, according to the Los Angeles Times. Other hospitals are reporting double their regular numbers of incoming patients.
Across the U.S., hospitals have reached capacity numbers not seen since this past January.
“It’s not like COVID-19 is the only game in town any more,” Peter Chin-Hong, a scholar of infectious disease at the University of California, San Francisco, told ABC News. “You can get COVID-19, then you can get a cold or then you can get RSV, and then you get influenza.”