BA.4 and BA.5 are sublineages of the Omicron variant of Covid-19. They are more transmissible than BA.2 but do not appear to be more dangerous. They would be responsible for the epidemic recovery observed in France in June. Symptoms, contagion: up-to-date information.
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 : BA.1, BA.2, BA.3, BA.4 and BA.5. After having the BA1 and BA2 variants, France suffered in June a progress of the BA.4 and BA.5 sub-lineages, responsible for a slight resumption of the epidemic. “So far, we have almost 18% of BA.4 or BA.5 [en France], and the rest in BA.2. But we can go from 18% to 85% in 15 days“, epidemiologist Catherine Hill warned on June 7 on BFM TV. “So we can have more than BA.4 and BA.5 in two weeks, and we don’t know at all what it’s going to do” she summarizes. What are these new variants Covid? Do they lead to symptoms different ? in France, dangers… Point.
What are the BA.4 and BA.5 variants?
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 is the rate of BA.4 and BA.5 in France?
“The detection of BA.4 and BA.5 is in increase” warned Public Health France June 2. “So far, we have almost 18% of BA.4 or BA.5, and the rest in BA.2. But we can go from 18% to 85% in two weeks“, alerted epidemiologist Catherine Hill on June 7 on BFM TV. As of May 16, 15 cases of infection with the BA.4 variant and 31 cases of infection with the BA.5 variant were investigated by the regional units of Public Health France. Omicron’s BA.4 and BA.5 sublines are subject to enhanced surveillance by Public Health France.
What are the differences with BA.2?
“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 was 50.5 years, higher than that of BA.1 infection cases investigated between November 2021 and January 2022 which was 35 years. The proportion of BA.4 or BA.5 cases over 40 years old (70.5%) was significantly higher than that of BA.1 cases. These sub-lineages could thus affect older people more.
What are the symptoms of BA.4 and BA.5?
The symptoms of the BA.4 and BA.5 positive Covid cases do not really differ from previous Covid Omicron cases. As Public Health France pointed out in May “them most common clinical signs were asthenia/fatigue (82.9%), cough (63.4%), fever (63.4%), sore throat (46.3%) and runny nose (43.9%)”.
Are BA.4 and BA.5 more contagious?
The Omicron BA.4 and BA.5 sub-lines replaced the BA.2 and resulted in 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). They now seem responsible for the epidemic rebound observed in France in June, defended Yves Buisson, president of the Covid cell of the Academy of Medicine on Europe 1: “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“, he explained on June 7.
→ In South Africa : the BA.4 growth rate is +8% per day compared to BA2; +12% for BA.5.
→ In Portugal : BA.5 could reach a growth rate of 13% per day.
This growth advantage”is likely due to their ability to evade immune protection induced by previous infection and/or vaccination, particularly if this has diminished over time“explained the ECDC at the end of May.
Are BA.4 and BA.5 more dangerous?
“There is currently no no indication of gravity change for BA.4/BA.5 compared to previous Omicron lines“said the ECDC on May 13.”No hospitalization has been reported among the investigated cases of BA.4 or BA.5 infection. Also, no critical care admissions and no deaths were reported“said Public Health France in its point of May 18.
Sources:
– Epidemiological update: SARS-CoV-2 Omicron sublines BA.4 and BA.5, ECDC, May 13, 2022
– Risk analysis on emerging variants of SARS-CoV-2 carried out jointly by Public Health France and the CNR for respiratory infection viruses, May 18, 2022
– Epidemiological Bulletin, Public Health France