A new killer strain of bird flu terrorising China could pose a risk to New Zealand, a flu expert said today.
More than 100 people have been diagnosed with the "unusually dangerous" H7N9 flu in China, with reports of at least 22 dead.
News that a 53-year-old Taiwan businessman picked up the virus while visiting China earlier this month - the first reported case outside the mainland - has sent alarm bells ringing for health officials and governments around the world.
"There is a risk here, and we have to continue to reassess the situation," said Canterbury virologist Dr Lance Jennings of the National Influenza Specialist Group.
"To hear that a traveller from Taiwan has contracted it while in China escalates the level of concern.
"But there are still a lot of unanswered questions. The important thing to remember when dealing with flu is to expect the unexpected."
Dr Jennings said because the virus was new, the seasonal flu vaccine offered no protection, and the population would have no natural immunity.
Unlike the H5N1 virus, which caused the 2009 pandemic, the new avian flu strain did not cause large outbreaks among poultry, making it difficult to identify when bird populations were infected.
"It is only when it crosses the species barrier into humans that the virus has been discovered."
It was also affecting largely older people, compared to the H5N1 which affected younger adults.
Dr Jennings said New Zealand's pandemic plan was well tested, and information had been sent to district health boards and laboratories to ensure anyone presenting with symptoms of the virus was identified and tested.
The World Health Organisation (WHO) said investigations into the possible sources of infection and reservoirs of the virus were ongoing.
Until the source of infection has been identified, further cases of human infection with the virus in China are likely, it said.
So far, there has been no evidence of the virus being passed on from human to human.
"This is definitely one of the most lethal influenza viruses we have seen so far," WHO flu expert Dr Keiji Fukuda told a news conference in Beijing today.
"When we look at influenza viruses this is an unusually dangerous virus."
In total, 108 laboratory-confirmed cases of bird flu, including 22 deaths, have been reported to WHO.
In a statement on Tuesday, WHO was not recommending any travel or trade restrictions, or screening at points of entry.
Earlier this week, before the Taiwan case came to light, the Ministry of Health said it was not considering screening travellers at airports here, but said it would review the situation if anything changed.
Health Minister Tony Ryall said New Zealand's health system was "ready to respond" to any increased risk of bird flu.
The ministry said they were unable to provide any further update today.