The vaccine against Covid-19 developed by AstraZeneca and the University of Oxford causes an immune response in older people, particularly at risk, according to results published Thursday, November 19 and 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 ensured 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 recalled The Lancet, «older adults have a tenfold risk of developing a severe form of Covid-19, so it is essential that a vaccine 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», Explained Professor Andrew Pollard, one of the leaders of the test 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 living in specialized institutions or those over 80.“, Notes The Lancet. These results should therefore be “confirmed in a larger sample of volunteers, including elderly people with health problems“: This is the goal of the phase 3 trials currently underway for this vaccine, which involve 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 given either the vaccine or another product, in order to be able to compare and evaluate the effectiveness of this one.
For its part, the Pfizer / BioNTech alliance assured Wednesday that its own vaccine was effective in people over 65 years old according to the phase 3 results, which has yet to be confirmed by their publication.