Using multiple surveillance systems, the Centers for Disease Control and Prevention (CDC) closely tracks new mutations and has identified two of particular concern: BQ.1 and BQ.1.1. The CDC refers to these BA.5 offshoots as “grandchildren of BA.5.” In the middle of September, the two BQ mutations together accounted for just over half a percent of infections in the United States. That proportion has rapidly increased. Now, data from the CDC’s COVID Data Tracker for the week ending October 22 show BQ.1 and BQ.1.1 make up more than 16 percent of cases in the United States. Meanwhile, BA.5 has dropped from almost 90 percent of infections in August to just over 62 percent. BA.4.6 currently accounts for 11 percent, and 6.7 percent of cases are BF.7. Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, told CBS News, “When you get variants like that [BQ.1 and BQ.1.1], you look at what their rate of increase is as a relative proportion of the variants, and this has a pretty troublesome doubling time.” The European Center for Disease Prevention and Control (ECDC) forecasts BQ.1 and its sublineage BQ1.1 will become the dominant coronavirus strains in Europe by mid-November to the beginning of December 2022. Almost 1 in 5 cases in France are now attributed to a BQ variant.
Will BQ.1 and BQ.1.1 Reverse a Decline in U.S. Cases?
In the United States, COVID-19 infections have been on a downward trend recently. The CDC estimates that as of October 19, the current 21-day average of weekly new cases (39,803) has decreased nearly 31 percent compared with the previous 21-day moving average (57,564). Bernadette Boden-Albala, MPH, DrPH, director and founding dean of the program in public health at the University of California in Irvine, warns that the new subvariants — along with more group gatherings indoors as winter nears and low booster vaccination rates — could threaten to reverse this nationwide decline in infections and potentially increase the amount of hospitalizations and deaths. “The subvariants we have experienced to date are derived from the omicron lineage, so it appears to cause less severe disease, but the difference is that they have a mutation in the receptor binding domain that allows it to pass through our primary line of immune defense,” says Dr. Boden-Albala. “You may feel the symptoms of COVID-19 much faster after exposure. Going forward, the hope is that new variants will also be associated with less severe disease, but it’s not a guarantee.” Scientists are currently evaluating the effectiveness of the new bivalent booster vaccines against these new subvariants. The bivalent shots were designed to protect against BA.5 and BA.4 omicron subvariants as well as the original coronavirus. According to CBS, Dr. Fauci said that since BQ.1 and BQ.1.1 are both related to BA.5, the new booster shots will “almost certainly” provide some cross protection. “However, data from individuals with breakthrough BA.5 infection suggest that the bivalent boosters will be less effective against these new variants compared to BA.5,” says Benjamin Pinsky, MD, medical director of the clinical virology laboratory for Stanford Health Care and Stanford Children’s Health in California.
U.S. Keeping Tabs on the XBB Subvariant Spreading Abroad
Based on international reports, the CDC is also closely watching a newly identified omicron sublineage called XBB, although it is still very rare in the United States. The Times of India reported on October 23 that COVID-19 infections caused by XBB have nearly doubled in India in one week. Based on forecasts, the news source predicted that XBB may grow to be the predominant subvariant in the country within a month. In mid-October, public health officials in Singapore cautioned that XBB was the predominant subvariant circulating in the community. On October 22, Eric Topol, MD, the founder and director of the Scripps Research Translational Institute in La Jolla, California, tweeted that indicators suggest the variant may be in descent in Singapore.
XBB May Pose a Special Threat to People Who Are Immunocompromised
The World Health Organization (WHO) has expressed concern about a study that suggests XBB has a significant ability to evade immune-system protections such as vaccination. “This is of concern for us because we need to ensure that the vaccines that are in use worldwide remain effective at preventing severe disease and death. So, the more this virus circulates, the more opportunities it has to change,” noted Maria Van Kerkhove, PhD, an infectious disease epidemiologist who serves as the WHO technical lead for the COVID-19 response. People who are immunocompromised may be particularly vulnerable to XBB. In a preliminary (non-peer-reviewed) study posted at the beginning of October on the preprint server bioRxiv, researchers found that XBB evaded Evusheld, a treatment of tixagevimab plus cilgavimab that the U.S. Food and Drug Administration has authorized to prevent disease in immunocompromised individuals. “New variants — BA.2.75.2, BA.4.6, BF.7, BQ.1.1, XBB — have developed spike mutations that allow the virus to evade recognition by the monoclonal antibodies present in Evusheld, the prophylactic antibody cocktail used to protect immunocompromised patients,” says Dr. Pinsky. “As these variants increase in prevalence, Evusheld will no longer be useful.” The research published in bioRxiv also indicated that XBB is likely to be resistant to bebtelovimab, a monoclonal antibody used to help fight the coronavirus infection by blocking the virus from attaching to the body’s cells. The National Institutes of Health issued a statement on October 19 also finding that the subvariants BQ.1 and BQ.1.1 may be unaffected by bebtelovimab.
