This sub-variant, which now accounts for 40% of new infections in the United States, is still very rare in France.
2023 already has its new variant that you should pay attention to. Three years after its emergence, Covid-19 continues to be a talking point, particularly with the end of China’s “zero Covid” strategy, which increases the risk of a strong resumption of the epidemic in a population less exposed to the virus and under-vaccinated . But the corona virus is not only a concern in Asia.
The US Centers for Disease Control and Prevention (CDC), which tracks the progression of the variants, reported last week that a new subvariant, XBB.1.5, was circulating in the US.
XBB.1.5 descends from XBB.1, which itself descends from XBB, which is a recombination of BJ.1 and BA.2.75. Simply put, it is the result of two subvariants of Omicron, the majority variant in many countries around the world.
A meteoric rise in the United States
In the last week of 2022 (December 25-31), it was included in more than 40% of the data sequencing positive tests for Covid-19. In comparison, it was present in only 3.7% of positive tests in the first week of December. Also according to the CDC, XBB.1.5 is the cause of 75% of Covid-19 cases in the northeast of the country.
“We hadn’t seen a variant progress so rapidly in several months,” said Pavitra Roychoudhury, director of Covid-19 variant sequencing at the University of Washington School of Medicine’s virology laboratory.
“This is the first time a recombinant has taken up so much space in a Western country,” CNRS Research Director Samuel Alizon told our Paris colleagues.
A priori no more virulent than the other subvariants
dr David Ho, a professor of microbiology and immunology at Columbia University, and his teams discovered that XBB.1.5 is less likely to be neutralized by antibodies from infected or vaccinated individuals, CNN reports. “Alarming” levels of immune leakage that could hamper the effectiveness of anti-Covid vaccines, concludes the professor, whose work has been published in the journal Cell.
Added to this is the ability to easily bind to the ACE2 receptor, which is present on human cells and which the virus uses to enter the body. “It has a better ability to enter cells,” confirmed Pavitra Roychoudhury. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, is nonetheless reassuring about the subvariant’s virulence.
“It doesn’t seem to cause any more serious illnesses and […] He has so much more immunity in the population that I don’t think it will take off,” the researcher said on CNN.
The CDC, while suggesting that XBB.1.5 “may be more transmissible than the other variants,” cannot confirm that it would cause more severe forms: “We are closely monitoring this variant to see how well our vaccines and treatments work against it.” .”
Very little available in France
Although no number has been reported by the CDC on the number of times the XBB.1.5 subvariant has been sequenced, its superiority over other mutations of the coronavirus has been established.
A situation that France does not know. In addition, XBB.1.5 is not mentioned in the latest Public Health France epidemiological bulletins dedicated to Covid-19. According to the Institut Pasteur, contacted by our colleagues from Paris, only about fifteen cases have been reported by sequencing in France.
Hugues Garnier Journalist BFMTV