"A large proportion of those who are coming to New Zealand are free, independent travellers ... no doubt there will be a number of solo or independent travellers who would have already arrived," Professor Ryan said.
It was a difficult time for an outbreak with many travelling as part of Chinese New Year, he said, and he had been hearing concerning accounts from the central Chinese city of Wuhan, where the outbreak began.
"My colleagues in Wuhan are telling me there's almost - in some locations, amongst some people - a sense of panic, and normal flu and cold symptoms are now being mistaken as the virus-borne systems ... there's a high degree of uncertainty at the moment."
Winter conditions and air pollution appeared to be exacerbating the situation, he said.
He said the population in Wuhan was about 11 million.
"Approximately five million might already have been leaving Wuhan in order to undertake their New Year travel. Most of that would have been domestic."
Beijing, Guangzhou and Shanghai remain the main ports visitors use to travel to New Zealand.
While the tourism industry would face immediate challenges from the outbreak, Prof Ryan said the impacts were unlikely to be felt long term, which similar incidents had shown.
"After the initial 12 months, things stablised and past patterns of growth and consumption and travel reestablish themselves ... undoubtedly over the next few weeks there is going to be high levels of uncertainty. There will be a drop off in numbers of visitors, the proportion of which is very difficult to assess.
He said the cancellations were only part of the concern.
"There are estimates that the impact of the virus on the Chinese economy may reduce that GDP growth by a further 1 percent."
Prof Ryan said the cost of travelling here meant it could be a less attractive destination if China's economy suffers from the outbreak.
"If in fact the Chinese economy is hit then I think that will reduce the number of people likely to come to New Zealand because we are seen as expensive and there are many significant, cheaper and equally attractive destinations that the Chinese would go to," Prof Ryan said.
The slowing down of the Chinese economy, availability of an array of attractive destinations and lack of five star accommodation all had the potential to work against New Zealand, he said.
About 408,300 Chinese visitors arrived in the year to November, down more than 9 percent from the previous year.
Visitor numbers from China had dropped in the last couple of years, but Prof Ryan said the prediction of one million visitors was likely to still happen, it might just take more time.
"In the longer term, I think we will continue to see a growth in Chinese visitors. But we have to remember ... we face a much more competitive situation, every country in the world is really after the Chinese tourist.
"At the moment, the number of outbound Chinese visitors is thought this year to be approximately 180 million, that's a very small proportion out of total population of 1.4 billion. We will have continued growth from China, we still need to be China ready, we still need to keep very close tabs on Chinese consumer spending patterns. We need to remember that China is also an ageing population."
That was a factor Prof Ryan said the tourism industry would need to eventually address, despite most Chinese visitors arriving while in their 20s, 30s and 40s.
- RNZ
