AstraZeneca Vaccine : Not a Second Class Vaccine

Many consider the AstraZeneca vaccine to be inferior. This assumption is wrong. Why is it underestimated how well this vaccination also protects?

Is AstraZeneca’s Vaccine Inferior? So far, all candidates have shown impressively: They do what is most important in this pandemic – they prevent people who have been vaccinated from getting seriously ill.

Who would want a vaccine with 60 per cent effectiveness when there are also some with 95 per cent? The vaccine from the British-Swedish company AstraZeneca does not have an excellent reputation with many people. According to a Hamburg Center for Health Economics survey, only two per cent of Germans would opt for the vector vaccine if they had the choice.

Medical staff, who are now mainly vaccinated with the AstraZeneca vaccine, are also resentful. Many wonders why they are getting a less effective vaccine. This is also confirmed by the immunologist and vaccine researcher Leif Erik Sander from the Berlin Charité. “People put the numbers on effectiveness next to each other, and some say: we don’t want that.”

An Understandable Consideration

After all, everyone wants the best possible protection for themselves, and 95 is more than 60. But the issue of effectiveness is, unfortunately (or fortunately) a little more complicated.

First of all, a clarification: new, not yet peer-reviewed data from Oxford University indicate that the AstraZeneca vaccine could be significantly more effective than 60 per cent if the first and second dose is at least twelve weeks apart (Voysey et al., 2021). The effectiveness is explained here using the previously published study data, based on which the European Medicines Agency Ema approved the vaccine. In the relevant analyzes, the first and second dose was four to twelve weeks apart, resulting in the effectiveness of 59.5 per cent.

Technical Term Effectiveness is Misleading

To compare the vaccines, we first have to clarify what effectiveness means because the word can be intuitively misunderstood. Something like this: A vaccine works for 60 per cent of those vaccinated, so many think. Four out of ten people get Covid-19 despite being vaccinated. But this assumption is wrong. “The technical term effectiveness is misleading because it is confused with everyday meaning,” says risk researcher Gerd Gigerenzer from the Harding Center for Risk Literacy. He has known the problem for a long time.

The annual flu vaccination is a good example. “If it is 50 per cent effective, that doesn’t mean that every second person vaccinated will get the flu,” says Gigerenzer. “Rather, there are only half as many cases among those who have been vaccinated than among those who have not been vaccinated.” The same misunderstanding can now be seen with Corona. Gigerenzer, therefore, suggests another expression that would make the idea easier: relative risk reduction.

Effectiveness of the Covid-19 vaccination

The effectiveness results from a comparison: In the vaccine studies, it was measured how many vaccinated test persons fell ill compared to the unvaccinated test persons. The difference is given in per cent. If half as many people who are vaccinated get sick as people who are not vaccinated, the effectiveness is 50 per cent, for example.

The word effectiveness can easily be misunderstood intuitively. For example, if a vaccine is 50 per cent effective, it will only work on half of those vaccinated. So five out of ten people would be unprotected after vaccination. It doesn’t seem right. According to previous studies, there is always protection against severe courses.

To classify this, you have to know that the sick in the corona vaccine studies include anyone who has developed even moderate symptoms, such as cough or fever. The t studies of the vaccine manufacturers suggest that the vaccinations protect against severe disease and death with much higher effectiveness.


It might sound complicated to some, but it gets to the heart of the matter: The percentage that reaches the public due to the vaccine studies indicates how much lower the number of diseases is in vaccinated people compared to non-vaccinated people. The effectiveness is, therefore, a comparison of the risk between vaccinated and unvaccinated.