A COVID-19 vaccine candidate developed by Sanofi and US group Translate Bio “will not be ready this year,” said the company’s CEO to Le Journal du Dimanche newspaper.

Clinical trials of this vaccine, which will be based on a technology known as mRNA — on which lean approved vaccines of Pfizer/BioNTech and Moderna — are expected to start this quarter.

In December last year, Sanofi had said it was targeting “earliest potential approval” of the shot in the second half of 2021, following positive preclinical data.

“This vaccine will not be ready this year, but it could be of use at a later stage all the more if the fight against variants was to continue,” said Paul Hudson.

The CEO gave no other details. Officials at Sanofi were not available for comment.

The news could mark another blow for Sanofi, already embattled with a delay for another COVID-19 vaccine candidate it hopes to bring to patients and for which the company has teamed up with Britain’s GlaxoSmithKline.

The two groups stunned investors last year by warning their traditional, protein-based COVID-19 jab showed an insufficient immune response in older people, delaying its launch towards the end of 2021.

Sanofi, last month, had agreed to fill and pack millions of doses of the Pfizer/BioNTech vaccine from July.