Covid-19: are we at the dawn of a ninth wave?

It’s new? The beginning of a new wave of Covid-19 could take shape on the next epidemiological curves. For six consecutive days, the number of cases has been on the rise, with a 41.1% increase on November 18 compared to last week, indicates Public Health France. As of November 19, there were 47,088 contaminations and more than 730 patients diagnosed with Covid-19 admitted to hospital each day. Added to this is a slight increase in the incidence rate (number of cases per 100,000 people) which stands at 287, or 11.1% more in a week. “Deaths from Covid are no longer declining and are expected to increase in the coming weeks in France,” the epidemiologist Antoine Flahault, director of the Institute of Global Health and professor at the Geneva Faculty of Medicine, told L’Express.

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This new stimulus comes almost as a surprise given that the strike of biologists, enraged by the savings that the government still intends to impose on them, prevented PCR test results from rising for several days. This was the case at the end of October, then from November 14 to 16 when they closed their laboratories, and during the two public holidays of November 1 and 11, during which very few tests were carried out. Consequence: the number of positive cases was, for several days, artificially low. As of November 16, for example, the positivity rate had increased (only) by 9.6%. It is currently at +23.2%.

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While it is possible that the beginning of an epidemic recovery has gone under the radar, this ninth wave can be explained by several factors: the return of the school holidays, the drop in temperatures and the spread of the Omicron BQ.1.1 variant in France. This BA.5 sublineage appears to be gaining ground in all metropolitan areas. “The highest levels are in Île-de-France, but the rate of increase seems to be slowing down,” estimates Public Health France. BQ.1.1 accounted for 32 percent of positive cases that moved to “sequencing” on Oct. 24, according to the latest Flash survey.

Like its predecessors, the BQ 1.1 variant proliferates thanks to “a permanent game of escape from the virus with neutralizing antibodies”, points out Hervé Fleury, virologist and professor emeritus at the CNRS and the University of Bordeaux. Bad news: BQ.1.1 appears to be able to “evade” vaccination more and infect people who are already infected more easily, according to “in vitro” studies. For this, “the variant has three mutations, 346, 444 and 460, which are important escape mutations”, and are present in the binding domain of the spike protein to the receptor that acts as a gateway in cells, explains the virologist. Good news, though: BQ.1.1 appears no more virulent than previous variants, according to the latest studies.

“A new wave across Western Europe”

This variant is not the only one out there. Without achieving the same success, “more than one hundred BA.5 sublineages are currently circulating in France, demonstrating the diversification within this sublineage,” adds Public Health France. And France is not an isolated case.

“All epidemiological indicators are currently converging in favor of the arrival of a new pandemic wave across Western Europe,” assures Antoine Flahault. In a report from the European Center for Disease Control and Prevention (ECDC), released Oct. 21, models suggest that COVID-19 cases attributable to BQ.1 and BQ.1.1 between mid-November and early December will account for more than half of infections. And at the beginning of 2023, again according to the ECDC, there would be more than 80% of cases on the European continent. Furthermore, BQ 1.1 would cause symptoms close to gastroenteritis, which could complicate outbreak monitoring.

Jacques Izopet, head of the virology department of the Toulouse university hospital, is more reassuring. “It is still too early to talk about a ninth wave. In the south of France the weather is still good and we have not seen a surge in the number of cases. The indicators are not worrying”. The specialist admits that he would be more concerned if this resurgence of the epidemic was brought about by a new variant – genetically different from Omicron – but, in the case of BQ.1.1, “we can hope that this resurgence is well controlled compared to the previous one”. Del rest, does it still make sense to speak of a “ninth wave”? The question, for Jacques Izopet, arises spontaneously: “the notion of wave is linked to the influx of hospitalized people. If they’re smaller, we can’t really talk about waves anymore.”

The arrival of new vaccines as a firewall?

Regardless of the name given to it, another pressing question: what form will this epidemic recovery take? “The vaccine still seems effective in reducing the risk of severe forms and, hopefully, of long-term Covid. However, it should not be able to prevent the surge of this new wave in the coming weeks,” points out Antoine Flahault. Another important parameter to understand the evolution of this new recovery: the number of target people who received the new vaccines adapted against Omicron subvariants BA.1, BA.4 and BA.5. For now, only “10 to 15%” have been bitten again. An insufficient rate, regretted the Minister of Health François Braun. However, these new so-called “bivalent” vaccines could generate more effective antibodies against BQ1.1. “On a theoretical level it is possible,” adds Hervé Fleury.

If no abnormally serious forms are reported, the concern for the elderly and the immunocompromised remains. “BQ.1.1 escapes monoclonal antibodies used for immunocompromised people, which can lead to treatment problems,” says the virologist. From there to justify the introduction of the mandatory use of the mask for everyone, indoors and on public transport? “I don’t think so, replies Jacques Izopet. For the moment, the rules of common sense are justified, but if the number of cases were to increase, it would seem logical to me to protect ourselves by wearing a mask, for example .” Hervé Fleury is more decisive on this question: “From this summer I say that we must wear masks again. There are people who have been vaccinated four times and who will be infected”. It remains to be seen whether Covid-19 will interrupt the end-of-year celebrations for the third consecutive year.