The French drugmaker made the move in light of the dominance of rival products from Pfizer-BioNTech and Moderna.
That decision comes despite positive results during trials.
Instead the firm will now work with the UK's GlaxoSmithKline on an alternative shot.
The move highlights the challenges of competing, particularly with BioNTech, which rose from relative obscurity through its alliance with U.S. giant Pfizer.
Investors appeared to welcome the move, which should save on development costs.
Sanofi shares gained as much as 1% on Tuesday (September 28), on a down day for the broader market.
The firm says it will now use technology developed as part of the vaccine effort to tackle other diseases, including influenza.
