Posted at 5:00 a.m.
spicule
The main difference lies in a series of mutations in the spike, the portion of SARS-CoV-2, the coronavirus responsible for COVID-19, which allows it to enter human cells. “It makes BA.4/5 less recognizable by the antibodies generated by vaccination,” explains Andrés Finzi, immunologist at the University of Montreal. “In addition, it has a greater affinity with the receptors of the human cell. Mr. Finzi’s results, obtained from healthcare workers, show that recognition of the “BA.” 4/5”, so named because the two BA subvariants. 4 and BA. 5 are very similar, falling very rapidly four weeks after the third dose of vaccine. “And these are in people whose first two doses were 16 weeks apart, which gives better protection. Another study, published by Columbia University researchers in Nature beginning of July, shows that compared to the Delta variant, the protection conferred by three doses is four times less good with BA. 4/5, and half as good with the original Omicron variant. “But it is in relation to the risk of infection, specifies Mr. Finzi. Protection against critical illnesses appears to be holding up. »
PHOTO MARCO CAMPANOZZI, PRESS ARCHIVES
Immunologist Andrés Finzi, professor at the University of Montreal
Innate immunity
Another difference is the BA subvariant. 5 is more resistant to “innate immunity”, an automatic immune response against all microbes. “We have seen an evolution of SARS-CoV-2 in its resistance to innate immunity as early as the Alpha variant,” explains Nevan Krogan, a virologist at the University of California at San Francisco, who is the lead author of a study on the subject published in December in Nature. “We are working on increasing this resistance with the Omicron, we will publish on the BA. 5 later this summer. »
Monoclonal antibodies
The same increased ability to resist different types of BA immunity. 5 allows him to evade monoclonal antibodies, a treatment against COVID-19. “With Omicron, we saw that several monoclonal antibodies worked less well, and this continues with BA. 4/5,” Mr. Finzi says.
Vaccines
Should we wait for a vaccine specific to the BA sub-variant. 5, as the FDA requested in June of pharmaceutical companies preparing a new Omicron vaccine? ” I do not know. It will be necessary to evaluate the costs and benefits of waiting for the end of the tests of the vaccine against BA. 4/5, compared to tests against the Omicron, which have been running for longer, Finzi says. But of course we are waiting for a new vaccine. »
More than two thirds of cases
The BA variant. 5 now accounts for 70% of new cases of COVID-19, according to data from the National Institute of Public Health of Quebec. However, the most recent data is from July 10, three weeks ago. Everything indicates that BA. 5 continued to gain traction. Indeed, in the United States, where the progression of variants has recently been shown to be similar to that north of the border, the newcomer now represents no less than 82% of new cases. Thus, if the seventh wave was first propelled by the arrival of the BA sub-variant. 2.12.1 is actually the arrival of BA. 5 which rapidly increased the number of cases.