Delta does not forgive half-vaccinations

SI can rest on my own vaccination successes, that is hardly an option in England with almost two thirds of the first vaccinated. On the island, the Sars-CoV2 variant “Delta”, which was first discovered in India and responsible for weeks of emergency, is spreading rapidly. For the British, it is a reality for which the German Chancellor was smiled at in the spring with a view to variant “Alpha” – the then so-called British variant B.1.1.7 -: the second pandemic in the country. English virologists are now actually talking about the two epidemics: the first with the alpha viruses is on the decline thanks to the aggressive vaccination campaign, the other with Delta (B.1.617.2) has been rising steadily since mid-May.

Joachim Müller-Jung

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

Similar in the United States: Despite good vaccination progress, Delta is spreading there in some parts of the country, where other virus variants seem to be running out of breath. The latest figures from Germany show less dynamism, they come from the end of May: Delta’s share of all Sars-CoV-2 variants in circulation was 2.1 percent. Alpha still clearly dominates with a share of more than 93 percent. But the numbers should be treated with caution, the genetic monitoring of the variants in this country is still much more patchy than in Great Britain or the USA.

So what can we expect from Delta, can it curb the new vaccination and low-incidence euphoria in the country? Delta will “gradually” assert itself in the next few weeks, recently predicted the President of the German Interdisciplinary Association for Intensive Care and Emergency Medicine, Gernot Marx, and SPD health expert Karl Lauterbach, that the variant would also become “important in autumn” in Germany. Acute horror prognoses are avoided. With rapidly falling infection numbers, it seems, the experts in this country are becoming more cautious. Nobody wants to cloud the good outlook, now that a good second pandemic summer has been announced in unison. But if you look outside the country, Delta divides the world of experts.

Optimists like the Californian physician Eric Topol, who is respected worldwide as a corona communicator, does not yet see any great new danger and the water glass with the Delta variant is still half full. At least where the vaccination progress has a significant impact. Topol summarizes the latest vaccination studies on Delta with an effectiveness of 95 percent, preventing severe Covid 19 disease after a double vaccination – at least with the mRNA vaccine from Biontech / Pfizer. And the likelihood of a new infection is also reduced by between 70 and 90 percent according to the status report recently published by Public Health England. That’s close to the vaccine’s great approval metrics.

Important: complete vaccination

However, the emphasis here is on the term double vaccination: Only the complete vaccination is extremely effective against Delta. The latest UK data presented by the Health Secretary earlier this week clearly shows that. Of 126 English people who had to be hospitalized in clinics for a Delta infection in the past few weeks, 83 were without vaccination, 28 had only received one dose and three of the clinically treated vaccinees had previously received both vaccine doses. The importance of the second vaccination is confirmed by a few days ago im „Lancet“ published comparative study with the mRNA vaccine from Biontech / Pfizer clearly proven. The levels of antibodies in the blood that work against Delta leave a lot to be desired after the first vaccination. In neutralization tests, which can be seen as a laboratory benchmark for the antibody effect, Delta scores similarly dubious overall as Beta – the variant first described in South Africa, which until then was considered the most unpleasant with regard to immune protection.


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