British corona study: vaccination protection decreases after a few months

A large-scale British study suggests that a third vaccination could be useful: The researchers found that protection against infection decreases after six months. The study makes no statement about a higher risk of severe disease.

According to a British study, protection against infection with the coronavirus is already a few months after the full vaccination. This underscores the need for booster vaccinations, emphasized Tim Spector, epidemiologist at King’s College London and head of the “Zoe Covid Study”. “We can’t just watch the protection slowly wear off while the number of cases and the likelihood of infection are still high,” he told the BBC. “We urgently need to make plans for booster vaccinations.”

However, the study does not make any statements about symptomatic illnesses, severe courses or the risk of dying from Covid-19. The decreasing protective effect relates solely to the risk of becoming infected at all. It is already known that the protection against a severe course is significantly higher than that against the pure infection.

Decline from 88 to 74 percent

The “Zoe Covid Study” examined the extent to which the two vaccines from BioNTech / Pfizer and AstraZeneca protect against infection. Both vaccines require two doses for complete protection.

According to the study, the protection of the BioNTech / Pfizer vaccine decreased from 88 to 74 percent five to six months after the second dose. With the AstraZeneca vaccine, the effectiveness dropped from 77 to 67 percent after four to five months. The researchers emphasized that the decreasing protective effect is expressly no reason not to be vaccinated. The vaccines are still a highly effective protection against Covid-19 for the majority of the population.

Data from 1.2 million test persons evaluated

For the study, the test results of more than 1.2 million subjects who were vaccinated between December 2020 and July 2021 were evaluated. The participants registered their vaccinations using the so-called Zoe Covid app, which volunteers can use to report illnesses and Covid symptoms for research purposes. For the infections evaluated, the researchers refer to positive test results between May 26 and the end of July. The results can thus be related to the highly contagious Delta variant that has prevailed in Great Britain since then.

Many people still have no vaccinations at all

In Great Britain – as in Germany – there is currently a discussion about whether, when and for whom a third vaccination might be necessary. According to experts, the main argument against such a booster vaccination is that vaccine is still scarce in many countries around the world and that many people have not yet been able to get a vaccination.

The World Health Organization (WHO) is therefore calling for no third dose to be inoculated for the time being. Several countries are already offering booster vaccinations – Israel, for example, already for people aged 30 and over.

Virologist Christian Drosten from the Berlin Charité is of the opinion that a third vaccination in autumn only makes sense for old people and certain high-risk patients. “After six months, the antibody level acquired through the vaccination goes down significantly, especially in very old people,” said Drosten in a recent interview. In special situations such as retirement homes, a refresher is therefore conceivable. In terms of numbers, this would hardly conflict with the international scarcity of vaccines.