No vaccine is currently available for human infection with influenza A (H7N9) virus, the World Health Organization (WHO) said Thursday in its latest update on the outbreak of the deadly disease in China.

However, it said that preliminary test results provided by the WHO Collaborating Centre in China suggested that the virus is susceptible to the neuraminidase inhibitors (oseltamivir and zanamivir).

The WHO-coordinated international response is also focusing on work with WHO Collaborating Centres for Reference and Research on Influenza and other partners to ensure that information is available and that materials are developed for diagnosis and treatment and vaccine development, it said.

To date, China has confirmed 14 H7N9 cases and five have died.

More than 400 close contacts of the confirmed cases are being closely monitored. Thus far, none of them have developed any symptoms of illness, according to the WHO. "At this time there is no evidence of ongoing human-to-human transmission," it said.

The WHO said it was yet to know the reason for the virus to infect humans. However, analysis of the genes of these viruses suggested that although they have evolved from avian viruses, they showed signs of adaption to growth in mammalian species.

These adaptations included an ability to bind to mammalian cells, and to grow at temperatures close to the normal body temperature of mammals, which is lower than that of birds, it said.

The WHO said it is prudent to follow basic hygienic practices to prevent infection, including hand and respiratory hygiene and food safety measures. It also advised not to eat diseased animals.

The organization said it did not advise special screening at points of entry with regard to this event, nor did it recommend that any travel or trade restrictions be applied.