Sanofi, GSK announced vaccine trial delay

Sanofi and GlaxoSmithKline have delayed advanced trials of their experimental adjuvanted recombinant protein-based COVID-19 vaccine after it failed to produce a strong enough response in older adults.

According to the drugmakers, phase 1/2 study interim results showed an immune response comparable to patients who recovered from COVID-19 in adults aged 18 to 49 years, but a low immune response in older adults. Sanofi says the results are likely due to an insufficient concentration of the antigen.

The partners will launch a phase 2b study in February 2021 with support from BARDA, as part of Operation Warp Speed. The study will include a proposed comparison with an authorized COVID-19 vaccine. If data are positive, a global phase 3 study could start in April 2021.

Ultimately this setback delays the vaccine’s potential availability from mid-2021 to late 2021.

Sanofi and GSK have contracts with multiple countries, including the United States and Britain, as well as the European Union.

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