Sanofi and GSK delay Covid vaccine until end of 2021 after low immune response in trials

‘We are disappointed’ says chief — but improved formulation is expected next year

The British government has purchased 60 million doses of the Sanofi/GSK vaccine (file photo) (Reuters)

Two pharmaceutical companies that are developing a Covid-19 vaccine have delayed their programme after trials showed a low immune response in older adults.

GlaxoSmithKline (GSK), which is working with Sanofi and is one of the seven companies from which the British government has purchased vaccines, made the announcement on Friday morning.

According to interim results of its phase one/two study, there was a lower immune response in older adults when compared with those aged 18 to 49, which was believed to be due to an “insufficient concentration of the antigen”.

Thomas Triomphe, executive vice-president of Sanofi Pasteur, said: “We care greatly about public health, which is why we are disappointed by the delay announced today, but all our decisions are, and will always be, driven by science and data.

“We have identified the path forward and remain confident and committed to bringing a safe and efficacious Covid-19 vaccine. Following these results and the latest encouraging new preclinical data, we will now work to further optimise our candidate to achieve this goal.

“No single pharma company can make it alone; the world needs more than one vaccine to fight the pandemic.”

Roger Connor, president of GSK Vaccines, said the results of the study were “not as we hoped”, adding: "It is also clear that multiple vaccines will be needed to contain the pandemic.

“Our aim now is to work closely with our partner Sanofi to develop this vaccine, with an improved antigen formulation, for it to make a meaningful contribution to preventing Covid-19.”

Further clinical trials will take place, and an improved antigen formulation is expected to be available in the fourth quarter of next year, pending successful development.

The news comes after trial data from Oxford University and AstraZeneca showed that their vaccine was safe and about 90 per cent effective.

On Tuesday, medical journal The Lancet published partial results from tests of the vaccine in the United Kingdom, Brazil and South Africa, with safety results for 23,745 participants and protection levels for 11,636 people.

Last month, AstraZeneca’s chief executive, Pascal Soriot, said an “additional study” was needed to validate the efficacy data of its vaccine after results showed a 90 per cent efficacy rate in participants who received less than a full dose initially, followed by a full dose later.

Other trials showed a 62 per cent rate when two full doses were administered.