Study: Confirmed Cases of H7N9 Bird Flu Drug Resistance

Laboratory tests have confirmed resistance in three H7N9 bird flu patients to a common group of antiviral drugs including Tamiflu, said a study published by The Lancet on Tuesday.

The "apparent ease" with which resistance emerged in H7N9 viruses to the only available treatment is a cause for concern, said the Chinese researchers who conducted the study.

On Monday, Chinese health authorities said no new human cases of the deadly H7N9 bird flu strain had been recorded for the second week in a row.

A total of 130 people have been infected, and 37 died.

For the latest study, researchers followed 14 H7N9 patients admitted to the Shanghai Public Health Clinical Center in China between April 4 and 20.

All had been given antiviral treatment, either oseltamivir or peramivir, and 11 showed a drop in viral count.

Three, however, had a "persistently high viral load" in spite of treatment and had to be placed on respiratory support machines.

Two of them died, said the study authors.