Sanofi (SNY) is facing an antitrust probe by the European Commission over a suspected breach of EU competition rules through an alleged misleading communication campaign, the regulator said Friday.

The Commission said it is concerned that Sanofi carried out a communication campaign that "disparages" the only competitor flu vaccine recommended for vulnerable patients with risk factors.

The regulator is investigating Sanofi's claims, suggesting that the evidentiary basis for CSL Seqirus' flu vaccine Fluad is weaker than that for its Efluelda, which contradicts findings by the European Centre for Disease Prevention and Control and national immunization advisory groups in Germany and France, the regulator said.

The Commission is also investigating whether Sanofi made misleading or inaccurate representations of national vaccination recommendations, as well as Sanofi's claims that Fluad is "subject to unresolved scientific objections from medical professional societies."

The regulator said that, if proven, Sanofi's practices may constitute an abuse of a dominant market position under EU competition rules.

Sanofi did not immediately respond to requests for comment from MT Newswires.