(Refiles with headline to reflect text)
PARIS, Dec 11 (Reuters) - An experimental COVID-19 vaccine of Sanofi and Britain’s GlaxoSmithKline showed an insufficient immune response in clinical trial results, the French drugmaker said on Friday, a blow to efforts to find ways to fight the pandemic.
The two companies said they planned to launch another study next year, hoping to come up with a more effective vaccine by the end of 2021.
The news comes as a disappointment for a crop of vaccines under development that rely on more conventional proven designs as the shot developed by Pfizer and BioNTech using breakthrough technology gets rolled out across Britain.
Friday’s results, Sanofi said, 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 likely due to an insufficient concentration of the antigen.”
Phase III studies were expected to start this month.
Sanofi said it would launch a phase 2b study in February of next year instead after a recent challenge study in non-human primates performed with an improved antigen formulation demonstrated better effects.
“The study will include a proposed comparison with an authorized COVID-19 vaccine,” the company said.
“If data are positive, a global Phase III study could start in Q2 2021. Positive results from this study would lead to regulatory submissions in the second half of 2021, hence delaying the vaccine’s potential availability from mid-2021 to Q4 2021.”
The two companies said they had “updated governments and the European Commission where a contractual commitment to purchase the vaccine has been made.”
Reporting by Matthias Blamont; Editing by Josephine Mason
Our Standards: The Thomson Reuters Trust Principles.