Virologist Christian Drosten spoke again on Twitter for the first time in two weeks. After “a lot of nonsense” spread in the past few weeks, he wanted to give some information about the SARS-Cove-2 virus.
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He provided an overview of the currently known omicron sublines. Three new variants are currently observed by Sars-CoV-2 surveillance: BA.4, BA.5 and the F486V mutation.
Omikron BA.4 and BA.5 are variants of Omikron with their own origin. They are not descended from the BA.1, 2 or 3 species familiar to us, but rather from a common ancestor of the omicron. In addition to Omicron, these variants have the spike L452R mutation, which is already known from Delta, among others.
Drosten warned that in hamster experiments this mutation resulted in increased virulence, so they were more contagious. In addition, immune escape is likely. “In addition, there is the F486V mutation that should also be associated with Immunescape,” Drosten explained. This means that omicron species at least partially bypass an immune defense against other variants of Sars-CoV-2 formed by the body through vaccination or infection.
“One sees a gradual increase in BA.4 and BA.5 since January in South Africa, but since mid-April there has been a sudden exponential increase at roughly Rt = 1.5. How is that possible?” the virologist wrote on Twitter.
It is possible that the variant had an immune escape advantage in communities where the BA.2 wave was not present, Drosten said. This is the case in South Africa. Accordingly, the sharp increase in incidence now is due to “loss of transmission immunity that started after the BA.1 wave in December”. The latency period will be appropriate.
So far, fortunately, there has been no impact on hospitalizations in South Africa, “but this could happen in the coming weeks”. BA.4 and BA.5 are also found in Europe, but they are still very rare.
As of April 18, a total of 25 samples of the BA.5 variant had been detected in Germany. The BA.2 subtype, which followed the first omicron variant and is easier to transmit, is still dominant in Germany. At the beginning of April, the Robert Koch Institute (RKI) gave its share of the samples 95 percent.
Instead, you will notice an increase in BA.2 strains with the L452Q mutation and additional L452 mutations in the United States and other countries like India. These mutants are summarized as BA.2.12.1.
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Against the background of the current BA.2 distribution in the USA, a strong increase in BA.2.12.1 can be observed there, but with a low overall incidence. “One could also consider the increased virulence of this variant due to the L452 mutation,” Drosten says. This means that this variant could also be a more contagious type of mutation that has been circulated so far.
In particularly affected areas, an increase in hospital stay can already be observed. However, their total number is still reassuringly low, according to Drosten. You have to keep monitoring the situation.
In Germany, the nationwide seven-day infection rate has recently decreased. The RKI gave the value of new infections per 100,000 inhabitants per week on Thursday morning at 826.0. The value on the previous day was 887.6. A week ago, the nationwide infection rate was 720.6.