Detected in France in September, a new subvariant of Omicron named "BQ.1.1" is continuing its inexorable progression, seemingly set to supplant the BA.5 variant of Omicron, which is currently in the majority.
BQ.1.1 derives from the sublineage BQ.1, which itself originated from BA.5. The new variant appears to have emerged in Nigeria in July. It has since spread to Europe, including France, Belgium, Denmark and Italy, as well as to other countries, including Japan, the United States and Australia.
At the very beginning of October, the European countries with the highest proportion of samples infected with these new subvariants (BQ.1 and BQ.1.1) were France (19%), Belgium (9%), Switzerland (9%), the United Kingdom (8%), the Netherlands (6%) and Italy (5%). In the United States, BQ.1 and BQ.1.1 represent 9.4% and 7.2% of Covid-19 cases, respectively. Taken together, these subvariants are second in prevalence to the BA.5 variant (62.2%).
Greater resistance to neutralizing antibodies
The daily growth rate of BQ.1.1 is 11% higher than that of BA.5. In a report from the European Centre for Disease Control and Prevention (ECDC), released on October 21, modeling suggests that Covid-19 cases attributable to BQ.1 and BQ.1.1 will account for more than half of infections between mid-November and early December. And by early 2023, according to the ECDC, more than 80% of cases in Europe will be due to these subvariants.
The growth advantage of BQ.1.1 over the circulating variants is probably due to its strong immunity evasion. Mutations in the viral envelope's spike protein, which allows it to enter cells, means it can evade antibodies. However, to date, there is no evidence that BQ.1.1 is associated with an increase in more severe infections.
Two studies by Chinese and American teams, published on October 4 and October 20 on BioRxiv (not yet peer-reviewed), suggest that BQ.1 and BQ.1.1 have a greater resistance to neutralizing antibodies compared to BA.5. Peking University researchers report that BQ.1.1 defeats therapeutic monoclonal antibodies, including Evusheld, which is used in subjects at risk of developing a severe form of Covid-19.
Increase in cases in Europe
Researchers at Ohio State University in Columbus, meanwhile, have investigated whether antibodies developed by patients who contracted Covid-19 during the BA.5 wave are able to neutralize the new subvariants. It turns out that, compared to the ancestral strain, BQ.1 and BQ.1.1 are respectively 10.4 and 10.7 times less neutralized by antibodies, meaning any previous infection with BA.5 may not protect against these new subvariants. Biologists also determined that BQ.1 and BQ.1.1 are more capable than BA.5 of inducing giant cell formation, a biological property that may promote a greater spread of the virus within the body.
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