PARIS, Dec 15 (Reuters) – French drugmaker Sanofi (SASY.PA) and its British partner GlaxoSmithKline (GSK.L) said on Wednesday a single booster dose of their recombinant adjuvanted COVID-19 vaccine candidate delivered consistently strong immune responses.”The booster was well tolerated, with a safety profile similar to currently approved COVID-19 vaccines. This is the most comprehensive booster trial to date to explore boosting across different vaccine technologies used for primary vaccination”, the companies said in a statement.”To provide the necessary data to regulatory authorities for the booster vaccine submission, the trial will continue to accrue the number of events needed for analysis, with results expected in Q1, 2022.”At the end of September, Sanofi dropped its plans for its own mRNA-based COVID-19 vaccine because of the dominance achieved by BioNTech-Pfizer (22UAy.DE) (PFE.N) and Moderna (MRNA.O) in using the technology to fight the pandemic. L1N2QU0BISanofi is hoping for a comeback after falling behind rivals in the race for COVID-19 shots, with a vaccine candidate based on the more conventional protein-based approach. “Preliminary results from the VAT0002 clinical trial investigating the safety and immunogenicity of the booster showed neutralizing antibodies increased nine to 43-fold regardless of the primary vaccine received (AstraZeneca (AZN.L), Johnson & Johnson (JNJ.N), Moderna, Pfizer/BioNTech) and for all age groups tested”, Sanofi said.The company said this was the most “comprehensive” booster trial to date as European countries are both grappling with a new wave of COVID-19 infections fuelled by the Delta variant of the virus and are gearing up for the new more contagious Omicron variant.”The ongoing global Phase III trial … includes regular reviews by an independent Data Safety Monitoring Board (DSMB). During its last review, the DSMB identified no safety concerns and recommended the trial to continue into early 2022 to accrue more data,” the companies said.Sanofi also it was continuing “its contribution to global public health needs” with the manufacturing of up to half a billion doses from BioNTech/Pfizer, Moderna, and Johnson & Johnson(JNJ.N) vaccines.