OMICRON BA5. BA.5, a sub-variant of the Omicron variant, was still the majority in France in October. A vaccine targeting BA5 has been authorized in France. What are the most common symptoms? How to avoid contagion?
[Updated October 7, 2022 at 11:23 a.m.] The initial virus of the maladie Covid-19 , Sars-Cov-2, mutated several times to the variant Omicron which began to arrive at the end of 2021 in France. Now ubiquitous, this variant has five sublineages of which the BA.5 . ' It represents 91% of positive tests in France during the September 19 Flash survey ' indicate Public Health France in its October 6 epidemiological update. ' The BA.4 sublineage continues to circulate at stable levels, with 8 % of interpretable sequences “adds the organization. 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 . It has been available in France since October 3. This vaccine mRNA is reserved for use for the booster dose only. 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 to circulating strains, much like the vaccine against influenza which changes every year. Among the it is symptoms the most common, the tiredness, cough and fever .
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 mutations L452 (like the BA.4) associated with the increased transmissibility of Delta.
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 experience anosmia [loss of smell] and ageusia [loss of taste], but also nausea, vomiting and diarrhea is higher for BA.4/BA.5' cases says the health agency. ' A Instead 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.
The duration of clinical signs is on average 7 days for BA.4 and BA.5 cases vs. 4 days for other Omicron cases .
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.
On September 20, the HAS gave its authorization for the distribution in France of a new vaccine from Pfizer targeting BA4 and BA5 sublines . What a vaccine mRNA is reserved for use for the booster dose only. This campaign will concern 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 Omicron sublines) is not a new vaccine but an adapted vaccine circulating strains, much like the flu vaccine that changes every year. ). ' Expected clinical efficacy for these new bivalent vaccines is at least equivalent or even superior to that of the original monovalent vaccines 'says the Authority, Regarding the people under 30, HAS maintains its recommendation to use only Comirnaty® vaccines (Pfizer BioNTech).
In September, the Omicron variant is dominant in France and its BA.5 sublineage has been the majority for two months now. In mainland France, BA.5 (all sub-lineages combined) accounted for 91% of interpretable sequences in the September 19 Flash survey, reports Public Health France October 6. BA.5 is also in the majority internationally, illustrating its higher competitiveness compared to BA.2. The Omicron BA.4 sublineage continues to circulate in the world and in France, but at lower levels than BA.5. In mainland France, he represented 8% interpretable footage from the September 19 Flash investigation.
' 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 June 27.
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 of deaths related to 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 showed 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.
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 subvariants' 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 appeared to be lower for BA.5 compared to BA.2. Neutralization levels decreased over time, at a faster rate for BA.5 ' emphasizes Public Health France.
- Risk analysis on emerging variants of SARS-CoV-2 carried out jointly by Public Health France and the CNR for respiratory infection viruses, September 7, 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, 13 May 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. withRxiv. 2022:2022.07.25.22277996.Source journaldesfemmes.fr