Three months after receiving the last shot of the vaccines from Pfizer or AstraZeneca, the effectiveness against the now dominant Delta variant drops significantly. This is the conclusion of a major study by the University of Oxford. More than three million nose and throat swabs were examined for the study.
After three months, according to the researchers, the protection of the AstraZeneca vaccine drops to 61 percent and that of Pfizer to 75 percent. In vaccinated people older than 35 years, the effectiveness decreased more quickly than in young people, the researchers write.
The research also states that if vaccinated people become infected with the Delta variant, they are likely to pass on the virus just as easily as unvaccinated people. The researchers found the same number of virus particles in the nose and throat in both groups.
“This can make group immunity a greater challenge,” Dutch researcher Koen Pouwels told ANP news agency. “Vaccines are probably the best at preventing severe disease, but slightly less effective at preventing transmission of the virus.”
The study has not yet appeared in a medical journal. It has yet to be peer-reviewed before it can be published.
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