Covid19. Symptoms, dangerousness… What we know about the BA.4 and BA.5 sub-variants

The increase in new Covid-19 contaminations is resuming in France, driven by the BA.4 and BA.5 sub-variants, which have notably caused an epidemic increase in Portugal in recent months. The latter notably presents 24.2% of the interpretable sequences in week 23 (from June 6 to 12), against 13.3% the previous week. But what do we know about them?

Read also: Covid19. What is the difference between variants and sub-variants?

new symptoms

Identified in early April by researchers in Botswana and South Africa, these new Omicron subvariants caused different symptoms from BA.1. Some tricky symptoms that we hadn’t seen so much with Omicron, like loss of taste and smell. These are symptoms that we had a lot with the very first virus, and that we observed much less, even almost more with Omicron. Which means that the virus would have greater invasiveness, an ability to invade cells that the previous one did not invade.​, details from West France Yves Buisson, epidemiologist and president of the Covid cell of the Academy of Medicine.

In a note updated on June 15, Public Health France reveals the results of case analyzes of the two sub-variants. Of 73 cases of infection with the BA.4 variant (67 confirmed cases and 6 possible cases) and 228 cases of infection with the BA.5 variant (210 confirmed cases and 18 possible cases) investigated, the most frequent clinical signs were asthenia/fatigue (75.7%), cough (58.3%), fever (58.3%), headache (52.1%) and runny nose (50.7%).

Furthermore, the likelihood of experiencing vomiting and vomiting was higher for BA.4/BA.5 cases compared to BA.1 cases​.

BA.4/BA.5 cases also reported a longer duration of clinical signs, according to Santé Publique France. Finally, asymptomatic cases seem to be fewer with this new subvariant: Only 9 cases investigated (3%) were asymptomatic (4 BA.4 and 5 BA.5), i.e. a lower proportion than for the BA.1 cases (10.9%)​.

A more dangerous variant?

But then, are BA.4 and especially BA.5 more virulent than their predecessors? If the latter seems to have “a greater invasion capacity” than the previous sub-lineages, we don’t have so many elements as for its dangerousness, believes Yves Buisson. We would be tempted, to understand this sub-variant and its effects, to look at the situation in Portugal, where the wave is ending. ” There have been a lot of cases, a lot of hospital admissions and deaths” in the country. Only, Portugal does not have the same background as France compared to Covid-19, points out the specialist. “There is not the same immunity. Portugal were relatively spared by the BA.2, so we can’t say that we will know what they had there. »

The sustained circulation of BA.2 in France, unlike South Africa and Portugal, could have a protective effect against BA.5 and further moderate its impact​, also indicates Public Health France.

For the time being, depending on the cases examined, “the hospitalization rate was not significantly higher for BA.4 and BA.5 compared to BA.1”noted the institution.

“No signal in terms of severity has been reported for these three sub-lineages, and the investigations of the cases of BA.4 and BA.5 carried out by Public Health France go in this direction”points out the National Public Health Agency.

Covid19. Symptoms, dangerousness… What we know about the BA.4 and BA.5 sub-variants

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