GSK and Sanofi delay Covid-19 vaccine

The companies said they would do more work on the vaccine and expected it to be available in the fourth quarter of 2021. The previous target for releasing the vaccine was mid-2021.

GSK said in phase 1 and 2 trials adults aged 18 to 49 showed an immune response comparable to patients who recovered from Covid-19 but the immune response in older adults was low, probably due to a weak concentration of the antigen.

The companies will start a Phase 2b study with an improved antigen formulation from February with support from the US Biomedical Advanced Research and Development Authority.

A recent study in primates using an improved antigen formulation showed the vaccine could protect against lung disease and clear nasal passages and lungs within two-to-four days. The results increased the companies' confidence in the platform's ability to produce a highly efficient vaccine, they said.

Roger Connor, president of GSK Vaccines, said: "The results of the study are not as we hoped. Based on previous experience and other collaborations, we are confident that GSK's pandemic adjuvant system, when coupled with a Covid-19 antigen, can elicit a robust immune response with an acceptable reactogenicity profile.

"It is also clear that multiple vaccines will be needed to contain the pandemic. Our aim now is to work closely with our partner Sanofi to develop this vaccine, with an improved antigen formulation, for it to make a meaningful contribution to preventing Covid-19."