Efficiency of Antagonist Drugs of the Cellular Transcriptomic Signature of Influenza A Virus Infection.

Inclusion Criteria: * patients hospitalized in intensive care units, * patients with mechanical ventilation invasive or non-invasive or Optiflow® ventilation system. * for a suspicion of severe flu, * with a symptoms for less than 96 hours, * and a respiratory failure defined by the necessity to resort to mechanical ventilation, invasive or Optiflow® Ventilation System The inclusion is conditioned to the detection of Influenza A viruses by PCR on nasopharyngeal swab. Exclusion Criteria: * No consent. * Hypersensibility to Oseltamivir * Negative PCR on nasopharyngeal swab * Symptoms for more than 96 hours. * Moribund patients at inclusion. * Pregnant/nursing woman. * Patients already taking diltiazem in the 48 hours before. * Patients having taken more than 3 intakes of oseltamivir before randomization. * Hemodynamic instability needing a dose of noradrenaline exceeding 2mg/h Contraindication to diltiazem: * sinusal dysfunction without device. * auriculo-ventricular heart block without device. * Cardiogenic pulmonary oedema. * Left cardiac failure * bradycardia\<40/min * Concomitant use of beta-blockers, antiarrythmic drugs, especially amiodarone. * Concomitant use of ivabradine, pimozide, nifedipine, ergot alkaloids.