The two companies will test their vaccine's efficacy against variants and when used as a second dose following a first injection with another vaccine.
Sanofi and GlaxoSmithKline (GSK) announced on Thursday that they are launching large-scale trials for their COVID-19 vaccine.
The Phase III clinical trial will involve 35,000 people aged 18 and older from several countries and will investigate the vaccine efficacy against the original strain of the virus as well as the B.1.351 variant, first detected in South Africa.
"Recent scientific evidence shows that antibodies created against the B.1.351 variant may provide broad cross-protection against other more transmissible variants," the two companies said in a statement.
Clinical studies to be launched in the coming weeks will meanwhile look at the protection the vaccine offers when administered as a second dose following a first injection with another jab.
"We are encouraged to see first vaccinations starting to take place in such an important, pivotal Phase 3 study, as we believe that our unique technology platform will provide a clinically-relevant vaccine option," Thomas Triomphe, Global Head of Sanofi Pasteur, said.
"We have adapted our vaccine strategy based on forward-looking considerations as the virus continues to evolve, as well as anticipating what may be needed in a post-pandemic setting. This trial is testament to the urgency and agility in our approach to help overcome the ongoing impact of this pandemic," he added.
The development of the Sanofi/GSK vaccine suffered an initial setback with the companies announcing in December that their jab triggered an "insufficient response in older adults."
They have since adapted the formula and announced earlier this month that their protein-based vaccine produced antibodies in 95 per cent to 100 per cent of cases following a second dose.
The vaccine remains on track to be approved in the fourth quarter of the year, Sanofi and GSK said. By then, most of the adult population in the US, UK and European Union is expected to have been fully inoculated.
In the EU, four vaccines have so far been approved: Pfizer/BioNTech, AstraZeneca/Oxford University, Moderna and Johnson & Johnson, the last of which is single-dose.
Some experts, including Pfizer CEO Albert Bourla, have however said that a third booster dose may be needed within 12 months following the second dose.
Sanofi is also developing a mRNA vaccine — the technology used by Pfizer/BioNTech and Moderna — with US therapeutics company Translate Bio.
It has also struck deals to produce tens of millions of doses of the Pfizer and Johnson & Johnson doses.