They are called BA.4 and BA.5 and they are the new subvariants of ómicron that at the moment are growing in prevalence in South Africa and spreading to other countries around the world, including several Europeans.
And although they do not seem worrisome at the moment, they have gained the attention of the World Health Organization (WHO) because, according to laboratory studies, their mutations could allow them to evade the immunity obtained with vaccines or with previous infections.
An issue that would increase your chance of “escape & rdquor; with respect to existing versions of omicron.
That’s why the magazine Nature echoes the study by Tulio de Oliveira, a virologist who runs one of the world’s strongest genomic surveillance programs for SARS-CoV-2. And he does it at the “Center for Epidemic Response and Innovation & rdquor; of the University of Stellenboschin South Africa, from where they already raised the alarm of the arrival of the omicron variant, at the end of last year.
And that is precisely where they have discovered these new sub-variants, as it is in South Africa where BA.4 and BA.5 have rapidly gained ground and are growing in prevalence over the last month.
Work diligently, but calmly
Go ahead, the researchers’ impression of the current situation in South Africa is good.
There are no alarming data and both the infection rate and the hospitalization rate for COVID-19 remain stable in the country.
That is why they say they are calm with these two strains. And they assure that “it is time to work carefully and diligently, but calmly”.
What happens is that in a very short time these new subvariants have been detected in nine countries.
However, they insist that this is not the time for alarms and that it is too early to determine whether their effect could be significant enough to justify government interventions and changes in the current way of dealing with the pandemic.
Because to make this type of decision, the scientists themselves consider that a change in three important data would be necessary:
- The difference in disease severity.
- If you avoid the vaccines.
- And if it causes an increase in the number of cases, since we cannot forget that even if they have the same severity as the current omicronan increase in infections still has a great impact on life.
This is how they found the new variants
April 1, Eduan Wilkinson, bioinformatician from Oliveira’s team in Stellenbosch, saw that researchers from the center’s laboratory and the National Institute for Communicable Diseases in Johannesburg had discovered, in their latest batch of data, several abnormal sequences of the SARS-CoV-2 genome.
They considered that by having some notable mutations in the SARS-CoV-2 region that encodes its spike protein (key for the virus to invade cells), it was urgent to investigate whether they were in more genomes than those sequenced in the country in recent months. .
And they did it so fast that, after working all weekend, found that they were found in 5% of the 500 sequenced genomes during the first week of March in South Africa.
But the first week of April, the proportion had already increased to 50%.
And in the last two weeks, the expansion of the two variants to 8 other countries, in addition to South Africa, has been uploaded to the GISAID data platform:
- BA.4 has been found in a small number of sequences in Botswana, Belgium, Denmark and the United Kingdom.
- BA.5 has appeared in China, France, Germany and Portugal.
What is dangerous about these sub-variants?
To make it simple, what these two subvariants have is a mutation What do they share and what is their name? F486V.
It sits on the spike protein and opens a door to infection at a site targeted by important antibodies generated by vaccinations or a previous infection.
The threat was already known, because last year virologists began to notice the vulnerability of this point in laboratory experiments, but it was believed to be almost non-existent.
For example, him virologist Benhur Lee of the Icahn School of Medicine at Mount Sinai in New York City, and colleagues found, while examining a promising monoclonal antibody treatment, that when exposed to an artificial virus only one version of the spike protein evaded their antibodies.
It was a nearly identical mutation to F486V.
But at the time Lee was relieved because the mutation was extremely rare in real life, so he was sure that antibody treatment would still be widely useful.
However, with the rapid rise of BA.4 and BA.5 in South Africa, it appears that the coronavirus has evolved such that the mutation no longer holds it back, Lee explains.
Risk analysis: At the moment there are no alarming data
Lorenzo Subissi, WHO virologist, He says the agency is currently tracking the two sublineages.
But he cautions that it’s too early to draw any conclusions about whether they pose an additional threat compared to other Omicron variants.
Immunologists are addressing the escape issue by exposing BA.4 and BA.5 samples to blood drawn from people previously infected with SARS-CoV-2 and from people who have been vaccinated.
But pending further data regarding BA.4 and BA.5, Tulio de Oliveira met with the South African government and a consortium of some 200 researchers to tell them that:
- “Without an increase in hospitalizations and with only about 1,200 new infections each day, no action is necessary.”
They warn that we must remain cautious
Scientists say that while it is true that this year’s SARS-CoV-2 variants cause, on average, less severe illness than previous versions of the virus, that is not a sign that the coronavirus will continue to weaken.
Because in addition to acquiring the usual mutations, SARS-CoV-2 can rapidly evolve through recombination, inserting a fragment of a sequence from one variant into the genome of another.
And if an omicron variant recombines with a different SARS-CoV-2 variant, it could produce a virus that evades immunity and makes people sicker or sicker.
“It would be great if these new variants were part of a trend where the virus is getting milder, but there’s no biological reason to believe this will always be the case.”