Conduct of the program “is delayed in order to improve the immune response in the elderly“, say the groups in a statement.

They now expect a vaccine to be made available in the fourth quarter of next year, when they initially hoped to submit an application for approval in the first half of 2021 and deliver a billion doses that same year.

Sanofi, which is developing this vaccine jointly with GSK, had recently indicated that it intended to start the very last human trials (called “phase 3”) at the end of December.

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Initial results insufficient

However, the interim results of the first trials (phase 1/2) showed a response below expectations.

If the immune response of adults aged 18 to 49 is “comparable to that of patients who have recovered from Covid-19 infection“, this answer is”insufficient“in older adults,” the statement said.

The laboratories therefore want “fine-tune the concentration of antigens to achieve a high immune response in all age groups“.

For this, they will conduct a complementary testing phase from February, based on a test recently carried out on non-human primates with an improved formulation of antigens.

“When we inject a large amount of virus into animals that have received the vaccine, we have excellent results, which is what gives us confidence“, commented to AFP Thomas Triomphe, vice-president of the vaccines branch of Sanofi.