International 27/01/2021

Is the Oxford vaccine less effective in older people?

Some German media report that it is less effective in people over 65, but there is no data to prove this

2 min
Representation of a series of Oxford vaccine doses
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BarcelonaThe efficacy data of the vaccine developed by the University of Oxford and AstraZeneca were published on December 8 in the journal The Lancet. The scientific article included the analysis of 11,636 participants in clinical trials conducted in the United Kingdom and Brazil. In these trials, people over the age of 55, who were recruited later, accounted for 12% of participants (8% were in the 56-69 age group and 4% were in the 70+ age group). According to the publication, the overall results of the trial showed an average efficacy of 70% against infection and a decrease in hospitalisations for covid-19 in the vaccinated group (there were two, one on the day of the first dose and one ten days later). In the unvaccinated group there were eighteen hospitalizations for covid-19.

On the results of the vaccine in people over 55 years of age, the study authors wrote that "there had been less time for cases to occur and, consequently, the values of vaccine efficacy in this age group were limited". They added that more data would be available in future analyses. However, in an earlier study published Nov. 18 in the same journal, the authors showed that participants in all age groups had high antibody levels after the second dose of vaccine. They also all had, according to the same study, high levels of T-cells, which are responsible for destroying infected cells and are a key part of the immune response to viruses.

In response to the information published in some German media that the efficacy of this vaccine was 8% in people over 65, the professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, Stephen Evans, explained to the Science Media Center that "these data do not suggest that there has to be a markedly lower efficacy at older ages". On the other hand, Adam Finn, professor of paediatrics at the University of Bristol, told the same agency that he had "no idea where the 8% figure came from". Salvador Macip, a doctor and researcher at the University of Leicester and the UOC, also referred to this: "We don't know how they reached this conclusion, if the data from the studies that included those over 65 years of age seem to indicate the opposite. It is true that, as more people are vaccinated, we have more information and the results may change a little, but it is a very big difference from what has been seen and they have not yet provided any conclusive evidence to prove it".