Tamiflu drug resistance in H7N9 flu cases raises concern

Resistance easily develops when patients take antiviral drugs such as oseltamivir (tamiflu) for treating h7n9 influenza infections. Researcher’s analysis, which includes 14 patients who were hospitalized in Shanghai within 2 days of starting therapy with Tamiflu, appears in The Lancet.

Meanwhile, Chinese health officials reported one more infection and one more death, pushing the overall number of people infected in the H7N9 outbreak to 132, including 37 deaths.

The goals of the Lancet study were to gauge viral loads in patients’ throat, stool, blood, and urine specimens during their hospitalizations and to look for antiviral resistance mutations and their impact on clinical outcomes. The patients were hospitalized from Apr 4 to Apr 27. Their median age was 71, and 10 of the patients were men.

All patients had pneumonia, four had acute respiratory distress syndrome and needed mechanical ventilation, and the conditions of three deteriorated further despite neuraminidase inhibitor treatment and ECMO. Two of the three ECMO patients died.

The researchers found that duration of illness before hospitalization or viral load in admission throat swabs didn’t predict the patients’ response to antivirals or clinical outcome. Those with falling viral load in throat swabs during treatment were more likely to survive, but viral loads stayed high in the three who got worse and needed ECMO.

They noted that the more persistent level could reflect the lack of earlier exposure to H7N9. “By contrast with seasonal influenza, antiviral treatment of A/H7N9 initiated many days after disease onset may still provide some clinical benefit,” they wrote.

Source: Center for Infectious Disease Research & Policy, USA



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