The novel influenza A virus H7N9 has shown a “concerning” ability to develop resistance to neuraminidase inhibitors such as Tamiflu (oseltamivir) and Relenza (zanamivir), according to a Lancet study.

Researchers studied 14 patients admitted to a Shanghai hospital with H7N9 influenza. In tracking patients’ viral loads, they noted that two showed persistently high loads after starting neuraminidase inhibitors. Both had also received steroid treatment. A mutation in the virus’s neuraminidase gene was associated with persistent high viral loads and poor clinical outcome.

The researchers wonder what, if any, role the steroid therapy had in the emergence of resistance. They advise early treatment with neuraminidase inhibitors.

Meanwhile, China has reported no new H7N9 cases for 2 weeks. The case count now stands at 131, with 32 deaths.

Source: Lancet