For a moment it looked as if the particularly infectious and in many countries dominant delta variant of the coronavirus would face competition.

Lambda had already been publicly proclaimed as the new, big number in the race for the SARS-CoV-2 evolutionary stages.

The professional world was not even aware of this variant - and was surprised how quickly one of these thousands and thousands had not yet been scientifically assessed and therefore uncorrected research papers by virologist teams, this time from Japan, had to serve as a template for another horror story of this pandemic .

Joachim Müller-Jung

Editor in the features section, responsible for the “Nature and Science” section.

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Lambda, that was the tenor of the scientists, could top the delta wave and make the Covid-19 vaccines practically unusable.

"Higher infectivity" and "immune resistance" were actually already mentioned in the title of the Japanese advance publication.

The following remarks on the laboratory and family tree analyzes of the lambda variant, however, quickly made it clear: Lambda is hardly suitable for escalations.

Antibodies can stop lambda

Although the variant has properties that make the pathogen significantly more contagious than the original virus, and with a new, large mutation in the crucial spike protein on the virus surface, it also contains a feature that may protect this virus from many antibodies and the vaccine Effect somewhat diminishes. However, in this respect, too, lambda is by no means the over-delta.

In laboratory tests with the blood serum of formerly infected persons and with antibodies from vaccinated persons, the antibody effect has shown that lambda has already adapted immunologically since the outbreak in Wuhan. This applies to both groups of vaccines, to the mRNA vaccines as well as to vector vaccines. But even with the new suspected immune escape mutation, it is hardly more dangerous than Delta. When it comes to the question of how far lambda could be more contagious, it also ranks behind Delta in the laboratory tests compared to other variants.

Whether Lambda will be able to displace Delta at all - similar to how Alpha, ie the "British" variant, was displaced by Delta a few weeks ago - was not very obvious even from the Japanese studies. In addition, other, similar experimental preprint studies, such as those of an American research group at the Grossman School of Medicine at New York University, came to the opposite conclusion: The antibodies obtained from those who have recovered or from those who have been vaccinated with mRNA are basically capable of to stop the lambda viruses from multiplying in the body and thus to stop Covid-19 diseases.

All of these virological studies are not yet suitable for making a final judgment on the new variant. But the experts are now clearly on a de-escalation course. This is also due to the available epidemiological data. Lambda was first discovered in Peru a year ago, so it is as "old" as the Delta variant first described in India. However, unlike Delta, which appeared worldwide over the course of the months and replaced other, highly infectious or immunologically adapted pathogen variants in many countries, Lambda spread rather slowly first in South America and was last identified in about thirty countries.

The number of cases is low; in Germany, according to the latest figures from the Robert Koch Institute, lambda was only found in one of around a thousand samples. In other countries and even in South America, where the variant spread mainly among unvaccinated people during the last wave of infections, Lambda has so far only been successful where there is no competition from similarly well-adapted and infectious SARS-CoV-2 variants.

When it became aware of this in June, the World Health Organization (WHO) did not put Lambda among the four "Variants of Concern" so far, the worrying variants of the coronavirus. Rather, Lambda - like Kappa, Epsilon and some other virus types - remains on the watch list as an "interesting variant". In any case, many virologists rate the new development stage of Delta, the so-called Delta-Plus, which first appeared in India and of which there are already further developments, as a possible new pandemic problem case higher than Lambda.