Dec 2 (Reuters) - The European Union"s drug regulator said on Thursday it had started a rolling review of the inactivated-virus COVID-19 vaccine from French biotech firm Valneva (VLS.PA), weeks after the EU signed a deal with the company for supplies of the shot. The decision to start the real-time review was based on preliminary studies that suggest the vaccine, VLA2001, triggers an antibody response against the coronavirus, the European Medicines Agency (EMA) said.