Sanofi and GSK announced positive results on Monday from a Phase 2 clinical trial of their joint Covid-19 vaccine, saying it generated strong levels of neutralizing antibodies in recipients across all ages studied. The partners said a large international Phase 3 trial will begin in coming weeks. The duo, two of the world’s largest vaccine manufacturers, is far behind in the effort to produce a Covid vaccine and lock down markets for their product, having suffered a setback in an earlier Phase 1/2 trial last year.