It is a setback when others start vaccination campaigns: French laboratories Sanofi and British GSK announced on Friday that their vaccine against Covid-19 would not be ready until the end of 2021, after less good results than hoped for of the first clinical trials.

French laboratories Sanofi and British GSK announced on Friday that their Covid-19 vaccine would not be ready until the end of 2021, after less good than expected results from the first clinical trials.

The conduct of the program "is being delayed in order to improve the immune response in the elderly," the groups said in a statement.

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

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Sanofi, which is developing this vaccine jointly with GSK - which provides its adjuvant - had recently indicated that it was planning to start the very last human trials (called "phase 3") at the end of December.

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

"Unsatisfactory formulation"

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

The laboratories therefore want to "refine the concentration of antigens so as to obtain a high immune response in all age groups". 

"The formulation of the product is not satisfactory. It is important to optimize it, it may take a little longer," Thomas Triomphe, vice-president of the vaccines branch of Sanofi, told AFP. disappointment".

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For this, they will conduct a complementary phase of tests, called 2b, from February, based on a test recently carried out on non-human primates with an improved formulation of antigens.

This showed that "the candidate vaccine could confer protection against pulmonary pathologies and cause the rapid elimination of the virus in the nasal passages and the lungs within 2 to 4 days", they underline in their communicated.

"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.

Will they arrive too late?

Traditionally, developing a new vaccine takes time and money: according to industry specialists, it takes around one billion euros and ten years on average.

For the Covid, research, boosted by exceptional funding and public-private partnerships, has however pulverized the usual deadlines.

Thus, 11 vaccines around the world have already passed through the final phase of clinical trials.

Among them, several have already published efficacy results, including the American Pfizer, which works in collaboration with the German biotech BioNtech.

The UK has already given the green light to their vaccine and started a vaccination campaign on Tuesday.

That of the American biotech Moderna could for its part be authorized as of next week in the United States.

So will Sanofi and GSK arrive too late?

These are "three to four months late, but ultimately with more information on better wording," says Mr. Triomphe.

"It will be up to our partners to decide whether they want to order doses."

Sanofi and GSK had in fact signed several delivery contracts, including one with the European Union, which has reserved 300 million doses of vaccines for 2021.