New virus variants probably do not pose a threat to the vaccine effect

Preparing for a vaccination. A variant of the original coronavirus has now been detected in several countries. Photo: Kurt Desplenter / BELGA / dpa (Image: dpa)
(Photo: Kurt Desplenter / BELGA / dpa)

Berlin – A ghost with the cryptic name B.1.1.7 is around. This variant of the coronavirus has now been detected in a number of countries, including several times in Germany. As things stand, it is probably more contagious than previous forms.

It would be even worse if the vaccines against B.1.1.7 and similar variants such as 501Y.V2, recently demonstrated for the first time in South Africa, were less effective or no longer effective. But this is not likely, as a current analysis confirms.

Accordingly, at least the vaccine from Biontech / Pfizer is also effective against certain variants of the coronavirus. The antibodies in the blood of 20 people who had been vaccinated were examined, as shown in the study by the US pharmaceutical company Pfizer and the University of Texas, which has not yet been published in a specialist journal and has been examined by independent experts. According to this, the vaccine will probably also achieve an effectiveness of around 95 percent in the modified forms.

Variant B.1.1.7 was initially detected in Great Britain. Similar to the variant 501Y.V2 that appeared in South Africa, it is characterized by changes in the genetic make-up, which result in several changes in the so-called spike protein on the surface. With it, the virus docks on body cells in order to penetrate them. The spike protein is also the indirect target of the RNA vaccines approved in Germany from Biontech / Pfizer and Moderna.

The agents stimulate body cells to produce this protein. This leads the body to believe that there is an infection, the immune system is activated and among other things forms antibodies against the protein. In the event of a later infection, they should help to ward off the virus quickly by binding to the spike protein and marking it as “hostile” for the defense.

Theoretically, it would be quite conceivable that changes to the spike protein of Sars-CoV-2 lead to the antibodies that are no longer able to bind. The vaccine would then be ineffective. But so far there is no evidence of this. Researchers are optimistic that it will stay that way. Because the immune response of a vaccinated person is not so easy to escape.

One of the reasons for this is that after the corona vaccination, people not only produce a single type of protective antibody against the spike protein, but many different ones, as the Berlin virologist Christian Drosten explained in the NDR podcast. Experts speak of polyclonal antibodies. This antibody mix can attack a large number of binding sites on the spike protein. Therefore, individual changes to this protein should initially have little effect.

There is a lot to suggest that “the changes so far are nowhere near so substantial that the vaccines that are now coming do not work,” says Hajo Zeeb, Head of the Prevention and Evaluation Department at the Leibniz Institute for Prevention Research and Epidemiology in Bremen.

In addition, there are limits to how much the spike protein can change, said Adam Lauring, an expert on the evolution of RNA viruses at the US University of Michigan, in a recent podcast. “It does not have an unlimited number of possibilities to escape the antibodies through changes, because it still has to do its job.” This includes attaching to body cells and allowing the virus to penetrate.

Drosten emphasizes another aspect. “Immunity is not just about antibodies.” So-called T cells, which are also part of the human immune system, have different binding sites than antibodies. At the beginning of an epidemic, the binding sites of the T cells are often not even affected by such mutations. Most vaccines also evoked very good T-cell immunity, so Drosten.

Drosten does not expect Sars-CoV-2 to have an effect like that of the flu – experts speak of gene drift – for a few years when the coronavirus has become endemic. Flu vaccines have to be adjusted again and again due to changes in the viruses.

In principle, if there is a high number of new infections, it is more likely that variants with mutations that are favorable for them will arise and spread, says Jörg Timm, head of the Institute for Virology at the University Clinic in Düsseldorf. “After the vaccination has now started, there may also be variants against which the vaccination response does not provide sufficient protection.” Therefore, cases should be examined very carefully in which an infection occurs despite vaccination.

“We will see more of such variants in the future,” says Isabella Eckerle from the Department of Infectious Diseases at the University of Geneva. In order to be able to recognize them at an early stage, it is necessary to decipher the virus genetic material from samples on a broad basis. Andreas Bergthaler from the Research Institute for Molecular Medicine of the Austrian Academy of Sciences (CeMM) emphasizes that the variants should be seen as a “wake-up call”.

The detection systems would have to be expanded and coordinated across Europe. But even if the worst case should occur and corona variants no longer respond to the existing vaccines: “In fact, RNA vaccines in particular can be technically modified relatively easily,” explains Timm. “It would then have to be clarified, however, what the renewed approval of a modified vaccine looks like.” Bergthaler emphasizes: “We must not believe that we have reached the end of the marathon with the vaccines.”

© dpa-infocom, dpa: 210108-99-942973 / 4

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