The European Commission opened an investigation on Friday into whether French drugmaker Sanofi breached EU competition rules in a flu vaccine marketing campaign.The Commission said it was concerned that Sanofi had carried out a misleading campaign to sell its "Efluelda" flu vaccine while disparaging a rival one called "Fluad" made by CSL Seqirus, primarily in France and Germany.In both markets, Sanofi holds a dominant position, the Commission added. "Sanofi is confident that it has acted, and continues to act, in full compliance with all applicable laws and regulations, including competition law," a company spokesperson said in a statement."The Company takes these matters seriously and is cooperating fully with the European Commission throughout the process."The investigation followed unannounced raids on Sanofi offices carried out in September 2025.