Paris: In a major setback to people, France's Sanofi and Britain's GSK on Friday said that their Covid-19 vaccines will not be ready until the end of 2021 after interim results showed a low immune response in older adults. Sanofi and GSK said the delay in their adjuvanted recombinant protein-based COVID-19 vaccine programme was to "improve immune response in older adults." In a statement, they said, "The vaccine's potential availability had been pushed back "from mid-2021 to Q4 2021," they said in a statement. American pharmaceutical giant Pfizer and its German partner BioNTech have said their vaccine had proven 90 per cent effective in fighting corona vaccine in ongoing Phase 3 trials involving more than 40,000 people. The vaccine candidate, developed by Sanofi in partnership with GSK, is based on technology that Sanofi has used to produce seasonal influenza vaccines and on immunological agents developed by GSK. The statement said that the Phase 1/2 study interim results 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 may be due to an insufficient concentration of the antigen. Also Read: World's largest iceberg may strike island this month,Penguins at risk Biden and Harris named Time mag's 2020 person of the year Hungary will seek to annul rule-of-law declaration in EU court: Justice Judit Varga