The BQ.1.1 subvariant is slowly but surely establishing its dominance in Quebec, where it and its elder BQ.1 now account for nearly a third of COVID-19 cases. But good news: Quebec researchers have just demonstrated that Moderna’s bivalent vaccine does indeed increase the ability of the immune system to recognize and fight this descendant of Omicron.
Data from the National Institute of Public Health of Quebec (INSPQ) released on Wednesday indeed reveal that the BQ.1 and BQ.1.1 lines accounted for 30.4% of the cases sequenced between November 6 and November 12.
These new sub-variants arrived on Quebec territory at the end of the summer. They are recognized for their increased ability to bypass the immune system of already infected or vaccinated patients compared to other variants. They are also resistant to monoclonal antibody treatments given to patients who develop a severe form of COVID-19.
These descendants of Omicron already account for more than 50% of the cases listed in the United States, and more than a third of the cases reported in France.
The family portrait of the Omicron subvariants in circulation in Quebec drawn up by the INSPQ thus clearly demonstrates that the BA.5 lineage (48% of cases, compared to 71% in mid-October), dominant since the 7th wave, is now in the process of being doubled by line BQ.1.1.
The effective bivalent vaccine
However, tests in vitro conducted with blood samples from Quebec healthcare workers exposed to the BQ.1.1 variant demonstrate that Moderna’s bivalent vaccine enhances the immune system’s ability to recognize and neutralize this variant. The administration of a bivalent vaccine after 3 doses of Pfizer would thus generate more immunity against BQ.1.1 than the granting of 4 doses of Pfizer vaccines.
“What we observe [avec le vaccin bivalent de Moderna]it is a jump in the immune response and a greater capacity to neutralize BQ.1.1 than with 4 doses [de vaccin de première génération] “, explains Andrés Finzi, professor and researcher in infectiology and immunology at the CHUM.
Although preliminary, these results confirm those obtained recently by other teams around the world regarding the ability of the bivalent vaccine to enhance the immune response to BQ.1.1 and other recent descendants of Omicron.
If the granting of a fourth dose of the first generation vaccine also seemed to enhance – although more moderately – immunity against the BQ.1.1 subvariant, the bivalent vaccine provides “a much better response” which justifies going look for that reminder, argues Professor Finzi.
“It is certain that with the very first vaccine [formulé avec la souche originale], we had a spectacular immune response, but this virus no longer exists. Newer variants are more resistant and continue to mutate. Even so, the bivalent vaccine provides an advantage to the immune system,” he says.
Clinically, the rise of BQ.1.1 further complicates things in hospitals, as this subvariant is resistant to all the monoclonal antibodies used in Canada to treat the sickest patients, including Evusheld, explains Dr.r Don Vinh, infectious disease specialist at the McGill University Health Center (MUHC). “We know that BQ.1.1 is not neutralized by these treatments and that we lose options to help hospitalized patients. These antibodies were also given [Evusheld] preventively for immunocompromised people. They might have a false sense of security right now and not be protected against BQ.1.1. It is clear that the future is no longer for monoclonal antibodies. Only antivirals remain effective. »