Flu drug limitations seen with new H7N9 threat

Researchers isolating a newly emerged H7N9 influenza mutation from a patient in China have discovered its ability to be less affected by the neuraminidase inhibitors that have to date provided the only option to control viral replication in severe bird flu infections.

Whereas the common, human strains of flu virus show less virulence after they have become resistant to drugs, this finding shows that the development of drug resistance in the new bird flu strain has no detrimental effect on the virus's ability to replicate.

"H7N9 influenza emerged earlier this year in China and has caused over 130 human infections so far. As a vaccine against this strain of influenza is not available yet, antiviral drugs are at the moment the only means of controlling infection with H7N9.

"It is known that treatment with antivirals can lead to development of drug resistance in influenza, and this study further underscores the need of prudent use of antivirals in H7N9 influenza infections."

Statement to the press, Nature Communications

This means that using one drug exclusively over another may not be "prudent".

The neuraminidase inhibitors used are Tamiflu from Roche (oseltamivir) and Relenza (zanamivir) from GlaxoSmithKline.