COVID-19. What we know about BA.4.6, this new sub-alternative from Omicron
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COVID-19. What we know about BA.4.6, this new sub-alternative from Omicron

The BA.4.6 variant tripled in one month in the UK, now accounting for 11% of new contamination cases. In the United States, it has been identified in at least 61% of new cases, according to health authorities (CDC).

It is already present in France, in 2% of the analyzed sequences, as in many other countries around the world.

BA.5 is still dominant, but…

As a reminder, in France, the dominant subtype is still BA.5, which accounts for more than 90% of the pollution since mid-July and the end of the seventh pandemic wave.

The emergence of new subspecies is a natural and expected evolutionary phenomenon. In the absence of an epidemiological or clinical indication, this does not constitute a signal of concern with respect to public health.

public health France

Like all other viruses, Covid-19 has already mutated hundreds of thousands of times. Only the more “privileged” versions with their new features can replace the others – generally because they are more portable. On the other hand, its severity is impossible to predict: it can be less deadly than more virulent. The Delta variant, in 2021, replaced a less dangerous version of the virus, before it was replaced by Omicron, which is less deadly in nature but more contagious.

Finally, both virus avatars are somewhat resistant to vaccines and antibodies associated with a previous infection: since the arrival of Omicron, vaccines have been shown to be much less effective in counteracting infection, and recurring infection. The release of Omicron “adapted” vaccines should improve protection.

recombinant variable

The BA.4 variant was first discovered last January in South Africa. However, the massive distribution of BA.5 did not make it disappear. So far, the shape of BA.4.6 is still very ambiguous. Its first discovery dates back to April 25, 2022.

However, according to Manal Mohamed, a University of Westminster microbiologist at The Conversation, this would be a species called “recombinant.” Recombination occurs when a new copy of the virus appears when one person is infected with two variants at the same time.

First seen in France in June:

Within BA.4, the sub-strain BA.4.6 was first detected during the week of June 13 and its detection during surveys appears to be stabilizing around 2%

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High immune escape

Very recently, he has not yet revealed all his secrets. It remains a “scion” of Omicron and is thus a highly contagious and less lethal version of the Delta variant, for example. Only factual observations, first, can tell us about its ability to thrive and the potential damage it can cause. Another unknown remains, the immune escape:

BA.4.6 will be similar to BA.4 in many ways, but it carries a spike protein mutation […]. The R346T mutation has been observed in other variants and is associated with immune evasion

Manal Mohammed Microbiologist at the University of Westminster

The researcher continues, “which means that it helps the virus escape from antibodies acquired during vaccination and a previous infection.”

According to a study published in September by researchers at the University of Oxford, antibody production will be lower with BA.4.6 compared with other subvariants of circulating Omicron.

A case that could be resolved by the prospective availability in Europe of specially modified vaccines against Omicron. According to Moderna, which is preparing to market a bivalent vaccine – as a reminder – against the original strain and the BA.1 sub-variant, this version is “effective against all strains of Omicron”.

Another troubling hypothesis: In BA.4.6, as in a few other still-in-the-minority sub-variables, many treatments (Evusheld, Paxlovid, etc.) would simply become ineffective, according to a Columbia University study.

Vaccination remains the key

Even with “old” vaccines – new ones are not yet available, and will only be available as a booster at first – protection against severe forms of Covid-19 remains high.

A full vaccination schedule (two doses plus a booster dose) provides protection from infection, even if it is much less than the original virus.

US President Joe Biden frankly declared the end of the pandemic on Sunday — even as the eighth wave threatened and more than 500 people died from Covid every day in the United States.

Nobody can know if BA.4.6 will be able to establish itself in Europe and/or in France. A small successor, BA.4.6.1, much more contagious, can be hit directly by a pawn.

France has seen the start of an eighth pandemic wave two weeks ago, with a 50-70% increase in pollution every week.

#COVID19 #BA.4.6 #subalternative #Omicron

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