By Ludwig Burger and Tassilo Hummel PARIS (Reuters) -French drugmaker Sanofi said on Monday an upgraded version of the COVID-19 vaccine candidate it is developing with GSK showed potential in two trials to protect against the virus’s main variants of concern, including the Omicron BA.1 and BA.2 strains, when used as a booster shot. While the two companies’ first experimental COVID shot is undergoing review by the European Medicines Agency, Sanofi and GSK have continued work on a vaccine that is molded on the now-supplanted Beta variant, hoping still that it will confer broad protection against…