France's pharmaceutical giant Sanofi, which has lagged rivals in producing new generation Covid-19 vaccines, has said it has decided to halt development of an mRNA candidate and focus on another vaccine against coronavirus.

Despite positive results at phase one and two trials, the candidate will not go to the third and final phase, Sanofi said, as they believed it would arrive too late to market with 12 billion anti-Covid doses already due to be produced by the end of the year.

Results from phase three trials of the other vaccine, developed with Britain's GlaxoSmithKline, are expected before the end of 2021.

The firms are combining a Sanofi-developed antigen, which stimulates the production of germ-killing antibodies, with GSK's adjuvant technology, a substance that bolsters the immune response triggered by a vaccine.

Sanofi said initial results for the mRNA product showed antibodies were created by 91-100% of test participants two weeks after a second injection.

No side-effects were observed and tolerance of the jab was comparable to other ARN vaccines developed by Pfizer-BioNTech and Moderna.

The immune response from the Sanofi mRNA vaccine "is strong" the company's vice-president for vaccines Thomas Triomphe said.

Sanofi had been working since March 2020 with Translate Bio, a US firm specialising in mRNA technology, and had even bought the biotech company for €2.7 billion at the start of August.

But Mr Triomphe admitted: "The need is not to create new Covid-19 ARN vaccines, but to equip France and Europe with an arsenal of messenger ARN vaccines for the next pandemic, for new pathologies.

"There is no public health need for another messenger ARN vaccine," against Covid-19, he added.

Sanofi has already launched new tests for a seasonal flu vaccine and intends to start clinical tests next year.

Germany's BioNTech, which developed a coronavirus vaccine with US giant Pfizer, announced in July that it aimed to start trialling a malaria vaccine using mRNA technology.

Messenger RNA works by providing human cells with the genetic instructions to make a surface protein of the coronavirus, which trains the immune system to recognise the real virus.

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