A university professor in the UK says the "uncontrollable spread" of COVID-19 remains a threat as the world makes preparations for a pandemic.
Coronavirus - which has infected more than 80,000 people and killed about 2700 worldwide - emerged in the Chinese city Wuhan.
The World Health Organisation has said it's too early to declare a pandemic. In New Zealand, the Ministry of Health is preparing should a pandemic be declared globally.
University of Reading associate professor for cellular microbiology Dr Simon Clarke said in a statement it seems the virus can pass between people who aren't necessarily showing symptoms.
Studies have shown some people can contract and spread the disease without showing any symptoms themselves.
Dr Clarke added this makes it even more tricky to track the virus.
"While it remains the case that most people who become infected will have light symptoms or none at all, such uncontrollable spread would present a serious risk to vulnerable individuals," Dr Clarke said in a statement released by the Science Media Centre.
It's important countries throughout the world take this uncontrollable spreading into account and increase monitoring of people from affected regions, said Dr Nathalie MacDermott, the National Institute of Health Research academic clinical lecturer at London's King's College.
Dr MacDermott said affected nations need to take prompt action before clusters of the virus start to affect significant proportions of the population.
"If this were to occur the already significant challenges in containing disease spread of COVID-19 may become insurmountable."
University of Otago researcher David Murdoch told The AM Show on Friday there was a "high chance" the virus will make it to New Zealand, and could perhaps already even be here.
"There's always a chance. There's a good chance we would pick it up - but there's absolutely no way we can be completely sure about that."