Sanofi and US company Translate Bio are developing the vaccine based on messenger RNA technology.
The phase 1 and 2 trials aim to verify that the vaccine is not dangerous and to provide initial information on its effectiveness.
Phase 3 would be carried out on many more patients to determine its effectiveness.
The first trials will include 415 people, with inital results expected in the third quarter.
Messenger RNA technology is also used in the Pfizer/BioNTech and Moderna vaccines, already authorised in the European Union, the United States and elsewhere.
It is the second vaccine developed by Sanofi against the coronavirus.
An earlier candidate, developed with Britain’s GSK, is recombinant protein-based, but its development is several months behind schedule and testing is only in phase 2, with hopes to launch it in late 2021.
Sanofi has also agreed to help produce Covid vaccines developed by Pfizer and Johnson & Johnson.