Sanofi and GlaxoSmithKline will apply for regulatory approval of their long-awaited Covid-19 vaccine as a primary jab and booster, after reporting an overall efficacy rate of 57.9 per cent.

The two large vaccine makers have lagged behind in the race to develop a Covid shot after a dosing mistake that forced the French drugmaker and its UK partner to redo an earlier trial. This delay meant the phase 3 trial was conducted while variants were circulating that could have reduced the efficacy of the jab.

The late-stage trial showed the vaccine was 100 per cent effective against severe disease and hospitalisation and 75 per cent effective against moderate to severe Covid. An early analysis suggests it could be more effective against disease caused by the Delta variant.