With the vaccines from BioNTech / Pfizer and AstraZeneca, the second vaccination dose is crucial for effective vaccination protection against the currently circulating variants of the coronavirus.

After just one injection, only every tenth vaccination leads to a sufficient concentration of antibodies in the blood.

French scientists from the Pasteur Institute have now published these results in the journal Nature.

Joachim Müller-Jung

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

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    Kim Bjorn Becker

    Editor in politics.

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      They show that the delta variant, which is spreading rapidly around the world, contains mutations that make the virus even more resistant than the alpha variant that has dominated to date.

      The amount of effective antibodies is accordingly reduced by three to five times compared to alpha.

      Similar unfavorable results were obtained with the beta variant, which appeared for the first time in South Africa but is less common in Europe.

      Value cannot be exactly transferred to everyday clinical practice

      In the French study, for which blood sera from dozens of vaccinated and convalescent people were used at intervals of up to four months, the scientists examined the effects of vaccinations on different variants of the coronavirus in the laboratory.

      The results make it clear how important the second vaccination is for building up a protective effect in the human body.

      With the so-called booster, both the mRNA vaccine from BioNTech / Pfizer and the vector vaccine from AstraZeneca provide very good protection against disease.

      In the study, more than 90 percent of the blood sera contained enough antibodies after a few months to neutralize all variants in the laboratory.

      However, this value cannot be exactly applied to everyday clinical practice.

      English studies had recently shown that the Astra-Zeneca vaccine can prevent around 60 percent and the BioNTech / Pfizer agent around 88 percent of Covid-19 diseases during a delta spread.

      The pattern also applies to those who have recovered.

      Regardless of the severity of the disease and the very different individual reactions of the immune system, the initial immune protection is gradually lost - and with it the protection against the variants that have only spread since January.

      Earlier infections should therefore no longer protect against new infections with the delta variant.

      In those who have recovered, a single vaccination increases the amount of antibodies in the blood so much that the person is well protected against Delta. The experiments of the Pasteur researchers with artificially generated monoclonal antibodies, which have so far been successfully used in studies on the antiviral treatment of Covid-19 patients, also show how serious the immunological consequences of the delta spread are. Due to the mutations in the binding protein of the virus, they have for the most part completely forfeited their effectiveness.

      As new figures from the Robert Koch Institute (RKI) show, isolated and completely vaccinated people in Germany are repeatedly infected with the corona virus.

      The institute put the total number of so-called vaccination breakthroughs nationwide on Wednesday evening at 3,806 - compared to around 25 million people who had full vaccination protection at the beginning of July.

      In its latest management report, the RKI emphasizes that the majority of the Covid 19 cases reported in the past few months can be traced back to people who had not been vaccinated.

      The institute estimates that the effectiveness of all vaccines is just over 90 percent.