The coronavirus vaccine being developed by GSK-Sanofi will not be ready before late 2021 after the pharma firms announced a delay due to unsatisfactory results in elderly patients.
The companies said they were expecting to have the vaccine ready in late 2021 after they announced a setback in the immune responses observed in older adults participating in their clinical trials.
In an online statement, Sanofi said that the interim trial results had shown an immune response “comparable to patients who have recovered from Covid-19” in adults aged 18 to 49, but “a low immune response in older adults.”
The British pharma firm said that the underperforming results in older adults could be “likely due to an insufficient concentration of the antigen,” a substance which triggers the production of antibodies by the immune system.
“The results of the study are not as we hoped,” GSK Vaccines President Roger Connor said, adding that he was “confident” in the companies’ ability to produce a Covid-19 vaccine which “can elicit a robust immune response.”
The companies said they would aim to “refine the concentration of antigen in order to provide high-level immune response across all age groups” and that they were expecting to kick off a new phase of clinical trials in February “with an improved antigen formulation.”
The study in question involved a total of 441 healthy adults in 10 locations in the United States, who were given two doses of the candidate vaccine or a placebo at 21 days apart.
The companies said that no participant developed any serious adverse effects during the study.
GSK-Sanofi’s announcement comes as several countries gear up to launch their mass vaccination campaigns against the coronavirus, after the UK began its massive vaccination effort this week, following approval of the Pfizer/BioNTech jab.
Pending approval from the EU’s drug regulator, Belgium said it is ready to begin vaccinating people in priority groups as early as 5 January.
Under current arrangements, Belgium is currently set to receive over 20 million vaccine doses from a range of manufacturers. It had not yet been decided whether it would subscribe to the GSK-Sanofi jab.