More than 41 million people in Germany are fully vaccinated against the coronavirus. How well are you protected against illness with the Delta variant? A look at current data.
In the approval studies, all vaccines currently available showed a high level of protection against the coronavirus: A double vaccination with Biontech / Pfizer accordingly reduced the risk of contracting corona. For the vaccine from Moderna, the protective effect was To protect the double vaccination with Astrazeneca – the value is slightly lower, but is also good. (That doesn’t mean that 60 percent of all vaccinated people stay healthy while 40 percent get sick. More on the importance of risk reduction)
However: A registration study does not always correspond exactly to reality. This is due, among other things, to the appearance of new virus variants. The studies were created in 2020 and show the protective effect against virus types circulating at the time. But meanwhile other variants are in circulation, Delta is particularly widespread.
How well do the vaccines against virus variants work?
“Current studies show that the available vaccines are also effective against virus variants,” writes the Robert Koch Institute (RKI). For the virus variant Alpha (B.1.1.7) the effects on the effectiveness of the vaccines are “low to moderate” compared to the wild-type virus. In Germany, the share of this variant was most recently twelve percent. with 84 percent.
The data situation on this variant is still very thin, as it has only dominated the infection process in many places for a few weeks. Some indications are encouraging, but the picture is not consistent.
The good news first: Recently published data from the UK show that a full vaccination with Biontech / Pfizer protects 88 percent against symptomatic disease with Delta (alpha: 93.7 percent). The full vaccination with Astrazeneca protects 67 percent (alpha: 74.5 percent).
After two vaccine doses, “only minor differences in vaccine effectiveness” were found in the Delta variant compared to the Alpha variant, the researchers write in the “”. In contrast, the protective effect was significantly reduced after just one vaccine dose – it was around 35 percent for both vaccines. “A complete series of vaccinations is essential for a good protective effect,” emphasizes the RKI.
Data from Alberta, Canada, a country with one of the highest vaccination rates in the world, points in a similar direction: you against Delta too. The effectiveness against diseases is given there as a flat rate of 91 percent against alpha and 85 percent against delta. In Canada, the mRNA vaccines from Biontech / Pfizer and Moderna were primarily used.
Data from Israel point in a different direction
That leaves Israel, the country that started a large-scale Biontech vaccination campaign at the end of 2020. There the data point in a different direction: In the country, the effectiveness of the vaccination against Sars-CoV-2 diseases fell at the same time as the spread of the Delta variant from 94 percent fended off by 93 percent.
point to a renewed decline in the protective effect in Israel. Should the data be confirmed, the protection against severe courses would still be a high 91 percent.
Why do the countries’ data appear to differ so widely? Andy Slavitt, US health advisor, sees a possible reason in falling antibody levels. There are “clear signs” that the levels decrease about six months after the second injection, according to Slavitt, but it is unclear whether other cells of the immune system – such as B memory cells and T cells – continue to offer protection.
He also pointed out that vaccination was carried out at a comparatively early stage in Israel. “The data covering the longest period comes from the original 35,000 study participants and the Israeli population,” said Slavitt.
Lower antibody levels in the elderly
Experts had recently repeatedly brought the possibility of third-party vaccinations as so-called “boosters” into play, especially for certain risk groups and the elderly. It may also benefit people who were vaccinated at an early stage due to their vaccination prioritization. However, it is not yet possible to estimate this with any degree of certainty. Biontech plans to provide more extensive data on this issue soon.
“There are groups where we know that the vaccination did not produce quite as high antibody levels. This affects older people, among other things,” said immunologist Carsten Watzl recently. “If it turns out that the antibody levels in these people are also falling quite quickly, you should definitely check whether you vaccinate this group a third time in the autumn in order to have good protection during the winter.”
For the majority of those vaccinated, a booster vaccination in the near future will probably not be necessary in the opinion of the expert. “It can be assumed that the majority of people who were vaccinated this year will get through the winter well.”
It will now be important to collect further data on the effectiveness of the vaccines against Delta and to examine whether there are signs of a decline in effectiveness in other countries over time. It is reassuring that the vaccines continue to offer a high level of protection against heavy sales.
