Is sub-variant ΒΑ.2 of “Omicron” more dangerous than BA.1; The LSE Professor of Health Economics Elias Mosialos in a post on facebook emphasizes that we will soon know from more targeted studies what exactly BA.1 differs from BA.2 in the unvaccinated and in the vaccinated population. He adds that neither the data from England nor Denmark show that there is cause for concern for more serious disease than BA.2 in vaccinated.
As we know and according to him World Health Organization, the “Omicron” variant, also referred to as B.1.1.529, has 3 main sub-variants: BA.1, BA.2 and BA.3. BA / 1 is prevalent in most countries but BA.2 is observed in several countries such as South Africa, Great Britain, the Netherlands and Denmark. BA.2 appears to be more contagious than BA.1.
But does BA.2 increase the risk of serious infection?
A recent study from Japan, which was widely reported in the international media and on twitter, compared the transmission of contagion and pathogenesis between Omicron BA.1 and BA.2. The results of this study have raised concerns that BA.2 infection may be causing a more serious illness.
Mr. Mosialos adds that we must not forget anything else. We watched her wave “Omicron” concerned mainly by the comparative advantage in transmissibility over Delta and notes:
This study thoroughly investigated, but in unvaccinated mice, cellular mechanisms of incubation and production of BA.1 and BA.2.
So yes, the results can help us understand how different the two types of Omicron work. But this does not mean that it is right to attribute the ability of BA.2 to cause serious disease in vaccinated people, because this happened in unvaccinated mice.
But there is evidence from South Africa to help us draw conclusions about BA.2 as the data collected by the South African NICD was made public. The data show that the same percentage of BA.1 and BA.2 cases were admitted to the hospital. Among the 95,470 molecular tests performed, the positivity for BA.1 and BA.2 was 3.4% and 3.4% respectively. Of the 3058 treated, a similar fraction had clinically severe disease. This corresponds to 33.5% of those who became ill and were treated with BA.1 and 30.5% of those who became ill and were treated with BA.2. After stratification of the data (for factors such as age, sex, comorbidities) no difference was observed in the risk of serious infection caused by BA.2 in relation to BA.1
Also, neither the data from England nor Denmark show that there is cause for concern for a more serious disease than BA.2 in the vaccinated.
In England, meanwhile, the incidence and prevalence of BA.2 continue to rise, but not at the rate that Omicron BA.1 “escaped” last December. The increase in BA.2 is gradually slowing down, with a doubling time of 4.5 days compared to 3.8 last week. Based on epidemiological analyzes, BA.2 accounted for 1 in 5 infections in England on 8 February. This, of course, is still an average that hides the significant regional fluctuations, ranging from 40% in London to 4% in the North East of England.
We will soon know from more targeted studies how exactly BA.1 differs from BA.2 in the unvaccinated and vaccinated population.
A new small study however for BA.2 it showed that similar to BA.1, there was little neutralizing potential of the virus before the third booster dose. But after the 3rd dose, the neutralizing antibody titers (ie the measurement in a blood sample) rose sharply against both BA.1 and BA.2. The neutralization degrees between BA.1 and BA.2 were relatively similar.
Individuals who have been vaccinated and subsequently infected with BA.1 have also been shown to have higher neutralizing antibody titers to BA.2
We must not forget something else, however, says Mr. Mosialos. “Between BA.1 and BA.2, there are similar but also many distinct mutations and the role of each of them is not yet known. Therefore we do not know exactly why BA.2 appears to be more contagious than BA.1. This is the role of ongoing research and researchers on coronavirus. And that’s what they do. “It’s our job to stay informed and to protect the most vulnerable.”
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