The Covid BA.5 variant, a sub-lineage of Omicron, is gradually replacing BA.2 in France and represents 24% of positive Covid tests. It is more transmissible and eludes the vaccine more. It could lead to loss of taste and smell. What do we know of him? What symptoms? What risks?
[Mise à jour le 23 juin 2022 à 12h30] The initial virus of the Covid-19 disease, Sars-Cov-2, mutated several times to the variant Omicron which began to arrive at the end of 2021 in France. Today in the majority, this variant has five sublineages of which the BA.5 which is released in June in France and gradually replaces BA.2 confirmed Public Health France in its latest variant risk analysis. “The epidemic recovery is linked to the arrival of new variants of the Omicron familythat are called BA.4, BA.5 and which broadcast faster than the previous one, the BA.2. We saw this BA.4 BA.5 arrive in South Africa, then in Portugal“explained infectious disease specialist Anne-Claude Crémieux on June 22 on France info. “If we compare BA.4, BA.5 compared to BA.2 which caused a surge in March, BA.2 was already different from the Omicron variant of December-January because it was more transmissible . But he is no longer immune to the vaccine. Now, we have BA.4, BA.5 which propagate better than BA.2. That one, he escapes the vaccine a little better. And it shows the evolutionary capacity of the virus which is able to evade vaccines, at the same time as increasing its transmission. But we also know that the symptoms are not more severe” added the infectiologist. Public Health France nevertheless emphasizes that “the probability of present anosmia [perte d’odorat] and ageusia [perte du goût]but also nausea, vomiting and diarrhea is higher for the cases of BA.4/BA.5 compared to those of BA.1″. What are these new variants Covid? Do they lead to symptoms different ? in France, dangers… Point.
What is the BA.5 variant?
BA.4 and BA.5 are sublineages of the Omicron variant of Covid-19. The BA.4 and BA.5 sublineages began to be identified in January and February 2022 in South Africa according to ECDC; early April according to Public Health France. They spread to Portugalleading to a new wave of Covid-19 in May, less serious than the previous ones.
What are the symptoms of the BA.5 variant?
According to Santé Publique France, the most frequent clinical signs in the event of infection with the BA.4 and BA.5 variants are fatigue, cough, fever and headache. Furthermore, “the probability of present anosmia [perte d’odorat] and ageusia [perte du goût]but also nausea, vomiting and diarrhea is higher for the cases of BA.4/BA.5 compared to those of BA.1″ the health agency said on June 15. The duration of the clinical signs is on average 7 days for the BA.4 and BA.5 cases against 4 days for the other Omicron cases.
What is the rate of BA.4 and BA.5 in France?
“In France, we observe a gradual replacement of BA.2 by BA.5, which represented 24.2% of the interpretable sequences of Flash Week 22 (compared to 13.3% for Flash Week 21). The detection of BA.4 is also increasing but at lower levels: 3.7% during Flash Week 22 vs 1.4% during Flash Week 21” noted Public Health France June 15. “More 300 confirmed or possible cases of BA.4 or BA.5 infection were investigated by the regional cells” adds the health organization. Omicron’s BA.4 and BA.5 sublines are subject to enhanced surveillance by Public Health France.
What are the differences with the BA.2 variant?
“If we compare BA.4, BA.5 compared to BA.2 which caused a surge in March, BA.2 was already different from the Omicron variant of December-January because it was more transmissible . But he is no longer immune to the vaccine. Now, we have BA.4, BA.5 which propagate better than BA.2. That one, he escapes the vaccine a little better. And it shows the evolutionary capacity of the virus which is able to evade vaccines, at the same time as increasing its transmission. But we also know that the symptoms are not more severe“said epidemiologist Anne-Claude Crémieux on June 22. “These two sub-lineages are quite similar to BA.2 but their Spike protein also has the mutations L452R/F486V and the R493Q reversion. BA.4 and BA.5 soon replaced BA.2 in South Africa. BA.4 and BA.5 present in this country a growth advantage by 8% and 12% per day compared to BA.2, respectivelyt” reported Public Health France on May 18. TheMedian age of cases investigated in France is 47 years old, higher than that of BA.1 infection cases (35 years).
Are BA.4 and BA.5 more contagious?
“The BA5 is more contagious than BA2. Considering the fact that it is more contagious, it escapes post-vaccination immunity a little better so we will probably continue to see this resurgence of new cases in the coming weeks“, explained Yves Buisson, president of the Covid cell of the Academy of Medicine on Europe on June 7. The sub-lineages of Omicron BA.4 and BA.5 replaced the BA.2 and led to a new epidemic wave in South Africa (5th wave). Same thing for the BA.5 exclusively in Portugal (without major epidemiological impact at this stage).
→ In South Africa : the BA.4 growth rate is +8% per day compared to BA2; +12% for BA.5.
→ In Portugal : “HASin Portugal, BA.5 is today majority, with 69% in week 21.. BA.5 was associated with an epidemic recovery in the country, but the peak of this wave that started at the end of April now seems to have passed. If this is confirmed, the amplitude of the wave will have been much less than the previous one.“ indicates Public Health France on June 15.
Are BA.4 and BA.5 more dangerous?
Data accumulated in several countries did not observe an increase in severity associated with BA.4 and BA.5. According to the latest ECDC epidemiological report reported by Santé Publique France on June 15, “There is currently no indication of any change in severity for cases infected with BA.4 or BA.5 compared to other Omicron sublines”. The rate
of hospitalization is not significantly higher for BA.4 and BA.5 compared to BA.1 and the majority of hospitalized cases present risk factors. “The median length of hospitalization (for BA4 or BA5 cases, editor’s note) is 5 days“adds the health organization.
Sources:
– Risk analysis on emerging variants of SARS-CoV-2 carried out jointly by Public Health France and the CNR for respiratory infection viruses, June 15, 2022.
– Epidemiological update: SARS-CoV-2 Omicron sublines BA.4 and BA.5, ECDC, May 13, 2022
– Epidemiological Bulletin, Public Health France