An experimental Covid-19 vaccine developed by Sanofi and GlaxoSmithKline showed a robust immune response in early-stage clinical trial results, enabling them to move to a late-stage study, the French drugmaker said on Monday.
Sanofi and Britain's GSK said a global Phase III trial would start in the coming weeks and involve more than 35,000 adults, with the hope of seeing the vaccine approved by the fourth quarter after having initially targeted the first half of this year before a setback.
Sanofi and GSK last December were forced to restart their trial when the vaccine showed a low immune response in older adults as a result of a weak antigen formulation.
The Phase II interim results showed 95 per cent to 100 per cent seroconversion following a second injection
Bosses now said there was a high immune response after a single dose, as they hope the vaccine could be used as part of any booster programme for later in the year.
"The Phase II interim results showed 95 per cent to 100 per cent seroconversion following a second injection in all age groups and across all doses, with acceptable tolerability and no safety concerns," Sanofi said.
Seroconversion refers to the vaccine's ability to prompt the body to produce antibodies against the coronavirus, as measured by blood readings. Later mass trials will be based on real infections.
Booster potential
"Interestingly, we also observed that our vaccine generated a higher antibody response in those with previous Covid-19 infection, we are analysing this further as it may suggest our vaccine could serve as a potential booster, regardless of what vaccine someone may have received (beforehand)," Su-Peing Ng, Sanofi's global head of medical for vaccines, told reporters.
Ms Ng said the vaccine had not been tested against so-called variants in the Phase II trial but that the Phase III study would be assessing it against various strains, including a virus lineage known as B1351 first detected in South Africa.
But Sanofi, Ms Ng said, has conducted parallel studies evaluating its vaccines against variants, with results expected to be published soon.
GSK and Sanofi's vaccine candidate uses the same technology as one of Sanofi's seasonal influenza vaccines. It will be coupled with an adjuvant, a substance that acts as a booster to the shot, made by GSK.
Some 162.75 million people have been reported to be infected by the coronavirus in more than 210 countries and territories since the first cases were identified in China in December 2019, while economies have taken a hit and restrictions have turned daily life upside down.
Europe and the United States have embarked on mass vaccinations programmes in the past months, raising hopes of a gradual reopening, although the virus is still in circulation in many regions, with variants causing concern.
Last month, the European Union executive's President Ursula von der Leyen said protein-based Covid-19 vaccines such as the one developed by Sanofi and GSK offered "quite a potential", a positive signal as the bloc develops its purchasing strategy for the next two years.
Sanofi's shot, however, even if approved, will come long after ones from Pfizer/BioNTech and Moderna, which have produced efficacy results of more than 90 per cent.
So far, Sanofi has purchasing agreements with the EU, the United States, Britain and Canada, as well as with the World Health Organisation-backed COVAX facility.
The company has pledged to help other drugmakers this year, striking "fill and finish" deals for vaccines made by Pfizer/BioNTech, Moderna and Johnson & Johnson.
In addition to its vaccine project in collaboration with GSK, Sanofi is working on a mRNA candidate with US company Translate Bio for which it has started clinical trials.
Sanofi and GSK shares were little changed in early trading.
