Containment measures introduced in Vietnam to prevent the spread of the 2009 pandemic H1N1 influenza did not succeed in halting the virus, but may have bought health services and clinical researchers valuable time, according to research. The study also showed that patients with mild disease responded favorably in terms of viral clearance -- and hence reduced transmission of the virus -- to oseltamivir, the most commonly-used antiviral drug, when given in the first 3-4 days of illness.