► What are the new differences?
These new Omicron sub-variants were identified in early April by researchers in Botswana and South Africa, actually between mid-December and early January.
Having become the majority in South Africa, and then in Portugal, they provoked new waves of the epidemic there. In South Africa, “where BA.4 and BA.5 were initially detected and where BA.4 is now the majority, the peak of the epidemic wave was in mid-May and its impact was very moderate. BA.5 is now the majority in Portugal, where the infection rate is increasing but still at lower levels than the previous wave,” summarized French Public Health on Friday.
Now, the beginnings of a pollution recovery are emerging and new incarnations of Omicron are being introduced elsewhere.
In Europe, BA.4 and BA.5 are quickly gaining ground in France where they should end up replacing BA.2, which has dominated since the beginning of the year, as well as in the UK and Germany. Among the specified sub-variables, BA.3 was never created.
En France, la porte-parole du gouvernement, Olivia Grégoire, a évoqué un “léger retournement de tendance” pour l’épidémie de Covid au sortir du conseil des ministres mercredi, parlant de “vigilance” mais “pas d’inquiéquétude” then.
The latest weekly numbers from Public Health France confirm the rebound in cases and the introduction of new subvariants. And a number of specialists note that the relaxation of sanitary measures also contributes to the resumption of the epidemic.
► More contagious?
Both sub-variables appear to spread faster than previous members of the Omicron lineage.
“BA.4 and BA.5 can spread as our immunity progresses, and they do so faster than BA.2 because they have the dual benefit of infection and immune escape. BA.4 et BA.5 induisent donc une vague plus tôt que BA.” 2 ne l’aurait fait», explique à l’AFP Mircea T. Sofonea, maître de conférences en épidémiologie à l’université de Montpellier, dans le sud de France.
Summer, synonymous with more outdoor activities, will it act as a brake on the possible resumption of the epidemic? “While summer can be relied upon to have a lower incidence than winter, it cannot, on its own, prevent a wave of contamination, as the example of the delta (fourth wave) in July 2021 demonstrated,” the epidemiologist upsets.
► More dangerous?
So far, there is no indication of an increased intensity of BA.4 or BA.5 compared to other Omicron lines, according to several scientists. But “it is still too early to measure it correctly,” nuance Mircea T. Sofonea.
Observations from South Africa and Portugal have, for now, led some observers to be reasonably optimistic about increased risks of hospitalizations and deaths.
“The BA.4/5 wave in South Africa has not resulted in many hospitalizations and deaths due to the high immunity of the population,” Tulio de Oliveira, a virologist at the University of KwaZulu-Natal in South Africa, whose team announced the discovery of Omicron in the fall of 2021, of course. We don’t know the long-term effects…”
In Portugal, where the population is more vaccinated but is also older, hospitalizations have nearly risen to the level of the previous wave. Unlike other countries, particularly in Europe, South Africa and Portugal had never before experienced a wave of BA.2.
Having passed a BA.2 wave that “could provide better protection against BA.4 and BA.5”, “genetically closer” to it, Public Health France was judged in May. But this has not yet been confirmed.
Either way, the immune shield erodes over time. “While the protection conferred by an Omicron infection or a third dose of the vaccine remains great after five months against the acute form, it is much reduced against any infection,” emphasizes the Montpellier epidemiologist.
For the most vulnerable groups, a fourth dose of the vaccine is already recommended in many countries, without waiting for autumn. If this is no longer mandatory, it is also recommended to wear the mask indoors in some cases by many scholars, such as ventilation.