Covid-19: AstraZeneca vaccine shows encouraging results in older people

The Covid-19 vaccine developed by AstraZeneca and the University of Oxford causes an immune response in older people, particularly at risk, according to results released Thursday which confirm announcements already made in October.

However, these intermediate results relate to a less advanced stage of development (called phase 2) than those which have been the subject of spectacular announcements over the past ten days by the manufacturers BioNTech / Pfizer and Moderna. Both have assured that their vaccine is 95% and 94.5% effective based on the results of the last stage of clinical trials (phase 3). These announcements have not yet been the subject of a detailed publication in a scientific journal.

The results of phase 2 of the AstraZeneca / University of Oxford project are published Thursday by the medical journal The Lancet. Main lesson: this vaccine provokes in the oldest subjects (over 56 years) an immune response identical to that which it triggers in the youngest (18 to 55 years).

This observation is important, because as The Lancet reminds us, “older adults have a tenfold risk of developing a severe form of Covid-19, and it is therefore essential that a vaccine intended to fight this disease is effective in this population group “.

“The immune response triggered by vaccines is often weaker in older adults because the immune system gradually weakens over time,” said Prof Andrew Pollard, one of the trial managers for the University of Oxford.

The researchers note, however, a limit to their study. The average age in the oldest group of participants was 73 to 74 years old and few of them had any health problems. “They may therefore not be representative of the entire elderly population, including people who live in special institutions or those over 80,” notes The Lancet.

These results must therefore be “confirmed within a larger sample of volunteers, including elderly people suffering from health problems”: this is the aim of the phase 3 trials currently underway for this vaccine, which relate to thousands of people.

Phase 2 involved 560 participants (160 aged 18 to 55, 160 from 56 to 59 and 240 over 70). They had been divided into several groups where they were administered either the vaccine or another product, in order to be able to compare and evaluate the effectiveness of this one.


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