Corona Weekly Report: Are we as threatened by a BA.5 wave as Portugal? – knowledge

BA.5 caused a wave of infections in South Africa and Portugal. Photo: Imago / Frank Hormann / Sven Simon

The omicron subvariant BA.5, which was first discovered in South Africa, has caused a wave of infections in Portugal. Do we have to adapt to this in Germany as well?

At first glance, the current corona data is positive. The infection rate in Baden-Württemberg is less than 200, and the number of patients treated in intensive care units with Covid-19 is around 90, its lowest level in almost a year. The R value, an important indicator of the further course of the epidemic, has been below 1 for several months.

But that has now changed. It has risen rapidly since May 25th and now stands at 1.09. This in turn could be related to the new omicron subvariant BA.5. It has already caused waves of infection in South Africa and Portugal and is also increasingly spreading in this country. Does that mean that we in Germany should expect increased numbers and more action again? We have looked at the available data and put it together for you. In our first graphic, we show the different sub-variables of the omicron and the ratio they play in the infection process in Germany:

In the area chart, BA.5 is currently just a small blue spot in the top right edge. In calendar week 20 (May 16-May 22), the rate was 5.2%. In fact, we can already see that their share is increasing, so the variable is gradually increasing. Accordingly, preliminary assessments for the 21st week (May 30 – June 6) are already showing 11.7%. If the ratio continues to double every week, BA.5 will be the dominant alternative in Germany by mid-June.

BA.5 was first discovered in South Africa. Here, the variant, along with BA.4, caused the infection to flare up again. Note: First, the variant BA.4, which appeared a little earlier, prevailed in South Africa. However, since the end of March, the BA.5 virus has spread rapidly here and already accounts for more than 30% of infections:

How quickly BA.5 becomes dominant in an environment where it does not compete with the BA.4 variant, which is also new, can currently be observed in Portugal. Here, BA.5 constitutes the majority of samples sequenced since mid-April and is responsible for a sharp increase in incidence to more than 1800. Sample sequencing is relatively slow in Portugal, but BA.5 can be identified by mutation-targeted tests demonstrating ‘del 69/70’. We show the estimated quota in this way in the diagram:

But why does BA.5 spread so quickly? On the other hand, ECDC reported that BA.5 is 13% more contagious than the BA.2 variant, which is also currently prevalent in Germany. On the other hand, there are several indications that BA.5 undermines immune protection through previous infections, particularly with the BA.1 omicron variant. Virologist Christian Drosten also told ZDF: “These variants (BA.4 and BA.5, editor’s note) have the L452R mutation in addition to the omicron in the spike, which was known from Delta, among other things, to have increased virulence in hamsters. Also, immune escape is likely.”

The efficacy of Omicron vaccines is unclear

This could also mean negative consequences with regard to new vaccines that have been adapted to Omicron. According to a Chinese study, there is already evidence that these may be less effective against the BA.5, BA.4 and BA.2.12.1 line that emerged in New York.

But there is also reason to trust Germany. Compared with South Africa and Portugal, posterior immunity in Germany is likely to be slightly higher. After all, the aura numbers here have decreased relatively recently. Another circumstance gives hope that in Germany, at least during the summer, accidents will not be as high as in Portugal: both BA.4 and BA.5 are very similar to the BA.2 variant. However, in Portugal and South Africa, there was no apparent wave with the BA.2 variant, which is why immunity to the new variants was not significant there.

More protection from infection with BA.2

So molecular biologist Ulrich Elling of the Austrian Academy of Sciences explained to “Standard”: “In Austria, we have built up quite a bit of immunity against BA.2. Unfortunately, the immune protection against additional infection after omicron infection does not last long, but for the time being We can still benefit from it.” And this can also be applied to Germany. The graphic shows the various developments in Germany and Portugal:

At this point, it is difficult to estimate the severity of a new wave of infection caused by the BA.5 variant. For the fall semester, however, caution is advised regarding BA.5. For example, immunologist Karsten Watzl of ZDF warns: “One does not know how the situation will develop during the summer. But if the numbers increase seasonally in the fall, then variables such as BA.5 will prevail.”

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