A new virus of the same type that caused the 2003 SARS outbreak is causing concerns, after causing 18 deaths in several countries.
The new type of coronavirus has caused severe pneumonia in small clustered outbreaks, including seven deaths in the past month in Saudi Arabia.
A second case in France yesterday was said to be the result of patient-to-patient transmission in hospital.
Dr Sue Huang, director of the WHO National Influenza Centre in Upper Hutt, said the virus was one of a group of viruses, one of which caused the SARS outbreak which claimed 1000 lives globally.
"This new coronavirus is not the SARS virus and they are different from each other. However, the fact that it's related to the SARS virus and that it can cause severe pneumonia is raising concerns."
Dr Huang said it wasn't known where the virus had come from, and it hadn't been detected in any animal species. There was no evidence of sustained person-to-person transmission, which would be needed to cause a pandemic.
Dr Huang said New Zealand needed to increase surveillance for the infection, including preparing laboratories to test for the virus, and raising awareness among healthcare workers so those coming back from affected areas with severe pneumonia could be identified.
Professor Michael Baker from the University of Otago's public health department said the World Health Organisation was right to take the threat seriously.
"The arrival of SARS in 2003 reminded us that entirely new human infections can emerge without warning and develop into global epidemics that may be difficult to control."
He said many of the systems for control of influenza would also be useful for containing other respiratory viruses.
Dr Siouxsie Wiles, infectious disease specialist at Auckland University, said it was too early to tell, but the evidence so far suggested the virus was unlikely to become a pandemic.
But the mortality rate of 18 deaths from 30 confirmed cases was "frightening".