OMICRON BA5. The sub-variant of the Omicron BA.5 variant is still the majority in France in December but tends to be replaced by one of its sub-lineages: BQ 1.1.
[Mis à jour le 2 décembre 2022 à 10h09] The initial virus of the Covid-19 disease, Sars-Cov-2, has mutated several times. The variant Omicron arrived at the end of 2021 in France. Now ubiquitous, this variant has multiple sublineages of which the BA.5 which is the majority in France. “BA.5 represented 93% interpretable footage from the Flash investigation week 45 (November 11)” noted Public Health France in its epidemiological update of December 1. BA.5 is also dominant in the world representing 72% sequences. more than one hundred sub-lineages of BA.5 are currently circulating in France. Among them, the most detected are BQ.1.1, BF.7, BA.5.2 and BA.5.2.1. “Sub-lineage detection BQ.1.1 continues to increase, with 49% of interpretable sequences in week 45“adds the health organization. “This genetic diversification is a normal consequence of the sustained circulation of this variant. This situation of co-circulation and diversification has already been observed on several occasions since the start of the COVID-19 pandemic, but must however be closely watcheds” noted Public Health France in the November 16 variant risk analysis. From symptoms the most frequent of BA.5, the fatigue, cough and fever.
What is the BA.5 variant?
BA.5 is a sublineage of the Omicron variant of Covid-19. It began to be identified in January and February 2022 in South Africa according to ECDC; early April according to Public Health France. It aired at Portugal, leading to a new wave of Covid-19 in May that was particularly virulent for the over 80s. He is particularly watched because he has L452 mutations (like the BA.4) associated with the increased transmissibility of Delta.
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 BA.4/BA.5″ cases says the health agency. “HASInstead of lasting an average of 4 days, they last rather 7 days or even 10 days so we contaminate longer“explained Dr. Damien Mascret on June 27. A new symptom is reported by Professor Luke O’Neill of Trinity College Dublin (Ireland): night sweats : “The disease is different because the virus has changed, night sweats being a new symptom“said the immunologist on Irish radio Newstalk July 7.
How long do symptoms of the BA5 variant last?
The duration of clinical signs is on average 7 days for the cases of BA.4 and BA.5 versus 4 days for other Omicron cases.
What is the incubation period of the BA5 variant?
There are no precise data on the incubation time of Omicron’s BA5 variant. On the other hand, we know that the incubation period of the Omicron variant is shorter than those of the previous Covid variants, i.e. 3 days against 5 days before.
Are vaccines effective against the BA.5 variant?
On September 20, the HAS gave its authorization for the distribution in France of a new vaccine from Pfizer targeting the BA4 and BA5 sublines. This vaccine mRNA is reserved for use for the booster dose only. This campaign is about people at risk of severe form of the disease as well as to those around them and to healthcare professionals. This bivalent vaccine (which targets the original strain of Sars-Cov-2 and the Omicron sublines) is not a new vaccine but an adapted vaccine circulating strains, much like the flu vaccine that changes every year. “Previous vaccines remain effective against severe forms, hospitalizations and deaths. However, bivalent vaccines are better suited to variants circulating, and may contribute to vaccine efficacy against infection. A third dose with a monovalent vaccine strongly increases the neutralization of all major Omicron sublineages. But this increase is even greater in people vaccinated and then infected with a sub-line of Omicron. Finally, a study in mice showed that bivalent vaccines enhanced the production of effective neutralizing antibodies against BA.5” noted Public Health France in its latest variant risk analysis of October 5. About the people under 30, HAS maintains its recommendation to use only Comirnaty® vaccines (Pfizer BioNTech).
What is the rate of the BA.5 variant in France?
The Omicron variant is dominant in France and its BA.5 sub-lineage is still the majority. In mainland France, BA.5 (all sub-lineages combined) represented 93% of interpretable sequences during the November 7 Flash survey, reports Public Health France. BA.5 is also in the majority worldwide (72%), illustrating its higher competitiveness compared to BA.2. The Omicron BA.4 sublineage continues to circulate in the world and in France, but at low levels (2%). more than one hundred sub-lineages of BA.5 are currently circulating in France, illustrating the diversification within this sub-lineage. Among them, the most detected are BQ.1.1 (32%), BF.7 (12%), BA.5.2 (8%) and BA.5.2.1 (5%).
Is the BA.5 variant 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“, explained Yves Buisson, president of the Covid cell of the Academy of Medicine on Europe on June 7. The symptoms last longer (7-10 days)”so we contaminate longer“explained Dr. Damien Mascret on June 27. “A recent study on the viral load of people infected with BA.5 suggests that the competitive advantage of BA.5 over BA.2 is not due to a higher viral load but is more likely dependent on increased affinity for its receptor and/or immune escape, both of which may be related to presence of the L452R mutation“indicates Public Health France.
Is the BA.5 variant more dangerous?
Data accumulated in several countries did not observe an increase in severity associated with BA.4 and BA.5. “In South Africa, a study comparing case fatality rates [proportion de décès liés au BA.5] during the different waves showed a fatality rate of 7.1% over the BA.4/BA.5 circulation period, against 10.9% during the circulation of BA.1/BA.2” reports Public Health France September 7. A first study from South Africa reported by Santé Publique France on July 6 comparing the risk of serious events between the Omicron BA.1 wave and the BA.4/BA.5 wave had shown that the risk of hospitalization/death was less in previously infected cases (70% lower) or vaccinated 3 doses (83% lower) compared to uninfected/vaccinated cases. “The median length of hospitalization (for BA4 or BA5 cases, editor’s note) is 5 days“indicated Public Health France on June 15.
What treatments are effective if you are contaminated with the BA.5 variant?
the Paxlovid remains the first-line curative treatment regardless of the variant or sub-variant of SARS-CoV2. “Its activity is not modified vis-à-vis BA.4 and BA.5 compared to the BA.1 and BA.2 sub-variants” confirm the General Directorate of Health July 11. This antiviral is administered orally. It can be prescribed by any doctor, and is available in health facilities and pharmacies pharmacy since February 2, 2022. In the event of contraindications to Paxlovid (in particular related to drug interactions), the treatment Evusheld (tixagevimab 150 mg/cilgavimab 150 mg) is available. It is administered in healthcare facilities by the intramuscular route. “In French patients treated with Evusheld, seroneutralization seemed weaker for BA.5 compared to BA.2. Neutralization levels decreased over time, at a faster rate for BA.5“ emphasizes Public Health France.
Sources:
– Risk analysis on emerging variants of SARS-CoV-2 carried out jointly by Public Health France and the CNR for respiratory infection viruses, October 28, 2022.
– Risk analysis on emerging variants of SARS-CoV-2 carried out jointly by Public Health France and the CNR for respiratory infection viruses, August 10, 2022.
– Risk analysis on emerging variants of SARS-CoV-2 carried out jointly by Public Health France and the CNR for respiratory infection viruses, July 6, 2022.
– 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
– Kislaya I, Casaca P, Borges V, Sousa C, Ferreira BI, Fernandes E, et al. SARS-CoV-2 BA.5 vaccine breakthrough risk and severity compared with BA.2: a case-case and cohort study using Electronic Health Records in Portugal. medRxiv. 2022:2022.07.25.22277996.