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BioNTech and AstraZeneca vaccines lose protective efficacy over time.
A large-scale English study has now shown the extent to which the protective efficacy of AstraZeneca and Pfizer/BioNTech corona vaccines diminishes after several months. At the same time, the researchers call for rapid plans for booster vaccinations.
Protection against coronavirus infection diminishes somewhat just a few months after full vaccination, according to one study. As a reference point, the British researchers took the protective effect determined in their study one month after the second dose of vaccine, which, according to them, was 88 percent with Biontech and 77 percent with AstraZeneca.
-14 percent after five months
At Biontech, the protective effect against infection declined 14 percentage points to 74 percent over the next four months, according to the large-scale study released Wednesday. For AstraZeneca, it was 10 percentage points within three months. Protection against infection was then 67 percent.
Test results from 1.2 million subjects
For the study, the team led by Tim Spector of King’s College London evaluated test results from more than 1.2 million subjects who were vaccinated between December 2020 and July 2021. Participants registered their vaccinations through the so-called Zoe-Covid app, which also allows volunteers to report illnesses and Covid symptoms for research purposes. According to the authors, the study is one of the world’s largest studies of vaccine effectiveness.
No conclusion on severe covid courses
For the infections evaluated, the researchers refer to positive test results between May 26 and the end of July. Thus, the results can be related to the highly contagious delta variant that has been prevalent in the United Kingdom since then. However, the study makes no claims about symptomatic disease, severe courses, or the risk of dying from covid-19. The decreasing protective effect relates solely to the risk of becoming infected in the first place.
According to Spector, the findings provide a possible explanation for increased infections among the fully vaccinated. At worst, the protective effect for elders and medical workers who were vaccinated several months ago could fall below 50 percent in winter, he warned. Given high infection rates in the U.K., that could again lead to more patients in the hospital and deaths, he said.
Plans for booster vaccination called for
“We need to make urgent plans for booster vaccination,” Spector urged. This third vaccination is currently being discussed in the UK, but has not yet been officially recommended by the relevant vaccination committee. However, the declining protective effect is explicitly not a reason not to get vaccinated, the researchers emphasized. The vaccines are still a highly effective protection against covid-19 for the majority of the population, they said.
— sources: vienna.at/APA/picture: pixabay.com
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