RKI weekly report
BA.4, BA.5, XD and XE: An overview of the Covid variants
BA.4, BA.5, XD and XE: It is easy to lose track of the Covid variants. Photo: Jens Büttner/dpa-Zentralbild/dpa
© dpa-infocom GmbH
With the unwieldy names of the newly discovered Covid species, it is easy to lose track. The RKI now lists some in the weekly report – including the number of proofs in Germany.
According to data from the Robert Koch Institute (RKI), several of the fairly new omicron sublines and mixed variants have so far been found relatively rarely or not at all in Germany.
As of April 18, a total of 25 samples were detected from line BA.5, according to the RKI weekly report on Thursday evening. The proportion in a sample was therefore 0.2 percent the week before last. More recent values are not yet available. BA.4 has not yet been proven. In Germany, however, the genome is only decoded in a small proportion of the positive samples.
The predominant subtype in Germany: BA.2
The predominant subtype in Germany is currently BA.2, in the random sample the RKI states the proportion for the week before last at over 95 percent. It was – even better transferrable – followed on BA.1. BA.4 and BA.5 have only recently become known and are classified as of concern by the World Health Organization (WHO) as part of Omicron. According to WHO information, evidence came from South Africa and some European countries. Both sub-lines had different characteristics than other Omicron variants, it was said – but details are still open.
In addition, the RKI reports evidence of several mixed variants (so-called recombinants) that are observed. They can develop when a host cell is infected with two different pathogens at the same time. The RKI records the following evidence: one each from XD (spike protein from omicron, remainder delta) and from XE and three from XG. The latter two are mixtures of BA.1 and BA.2.
The search for mutations
“The XM line detected most frequently (90 times) is a recombinant from the omicron sublines BA.1.1 and BA.2,” writes the RKI. This was identified for the first time in mid-February and has since been detected in several European countries, including Denmark, the Netherlands and Great Britain. It was said that the proof was partly also provided by a targeted search for certain characteristic mutations. The RKI also points out that the classification can currently still be error-prone.
So far, there has been no epidemiological evidence of altered transmissibility, disease severity and/or altered immune response in the recombinants compared to the original variants. It has been said that XE may be a bit more transferrable compared to BA.2.
Overall, the RKI speaks in the report of declining trends in several corona indicators in Germany. Among other things, key figures on hospital admissions and outbreaks in facilities are decreasing. In more than 200 laboratories nationwide, fewer and fewer PCR tests have recently been carried out, on which the official statistics are based. The RKI writes that the significant drop last week was also due to the Good Friday holiday. According to the report, more than every second test was positive. Overall, the health experts continue to assess the infection pressure in the population as high.