Skip to main content
Premium Trial:

Request an Annual Quote

Sanofi/GSK Vaccine Delay

A candidate SARS-CoV-2 vaccine from Sanofi and GlaxoSmithKline exhibited an insufficient immune response in early-stage clinical trials, delaying the companies' vaccine development timeline, Reuters reports.

Sanofi and GSK announced last April that they would be working together on a candidate SARS-CoV-2 vaccine using the approach Sanofi uses for its influenza vaccine and an adjuvant from GSK. At that time, the Guardian reported that the companies planned to have a vaccine ready by the second half of 2021.

However, Reuters now reports that while their Phase I/II trial indicated that the vaccine generated an immune response similar to that of recovered COVID-19 patients among 18-to-49-year-old participants, older participants had a weaker response. In a press release, the companies say that effect is likely due to insufficient concentration of the antigen.

"With this type of vaccine, the result is not a surprise, we know that more antigen is needed in older patients. But when in Phase I and II, drugmakers test tolerance and one cannot test strong dosages," Jean-Daniel Lelievre from Henri-Mondor hospital in France tells Reuters.

Sanofi and GSK add that they are planning a new Phase IIb clinical trial with a different antigen formulation and have revised their vaccine timeline.