Britain's Glaxo and France’s Sanofi are the world’s two largest vaccine companies but have been left floundering in their attempts to come up with a product by rivals Pfizer/BioNTech, AstraZeneca/Oxford University and Moderna.
All of those three companies have vaccines approved and are either being widely administered or, in the case of Moderna, soon to be.
Glaxo/Sanofi, meanwhile, stunned observers in December when they announced the candidate they were developing had shown no impact on the over-50s – the most critical group for Covid-19 inoculation.
The failed approach deployed Sanofi’s recombinant DNA strain used normally for flu jabs alongside GSK’s adjuvants, which are designed to enhance the immune response.
This new Phase 2 study will assess a refined formulation designed to spark an immune response in older adults
If results are positive, a Phase 3 study would follow almost immediately in the hope that a vaccine might be available in the final quarter of 2021, the pair said.
Development work on the new variants of Covid-19 identified recently is also underway, said the statement.
“Over the past few weeks, our teams have worked to refine the antigen formulation of our recombinant-protein vaccine, based on learnings from our initial Phase 1/2 study.” said Thomas Triomphe, Executive Vice President and Head of Sanofi Pasteur.
“We are confident that our vaccine candidate has strong potential and we are very encouraged by the latest preclinical data.
"This new Phase 2 study will enable us to identify the final vaccine formulation for adults of all ages."
Roger Connor, president of GSK Vaccines added: The world needs multiple vaccines and we are confident that combining our proven pandemic adjuvant system with this improved antigen formulation will have significant potential as the pandemic evolves;
Two injections will be given 21 days apart to 720 people in the trial with equal numbers of adults 18 to 59 years and those 60 years and above.
Astra and Pfizer's candidates slash hospital admissions after one dose
Meanwhile, there was more good news for people receiving the Pfizer/BioNTech or AstraZeneca PLC (LON:AZN)/Oxford vaccines.
A study in Scotland found that after four weeks after being inoculated, admissions to hospital of people who received the Pfizer candidate dropped by 85% with a 94% fall among those given the AstraZeneca/Oxford drug.
“These results are very encouraging and have given us great reasons to be optimistic for the future,” said Aziz Sheikh, a professor at the University of Edinburgh’s Usher Institute who co-led the study.
“I am very encouraged. We now have national evidence...that vaccination provides protection against COVID-19 hospitalizations," he added, saying he expected similar results from studies in England and Wales.