People who have contracted Covid-19 but haven't yet developed symptoms could be infectious for up to three days days before appearing unwell according to the latest research.
New Zealand's Director-General of Health Dr Ashley Bloomfield says the World Health Organisation research released today shows the virus still spreads the same way as it does with people who have symptoms.
"It's important to recognise that pre-symptomatic transmission still requires the virus to be spread through infectious droplets or by touching contaminated surfaces," he said.
"It may be that people are infectious for one to three days before they develop symptoms."
Dr Bloomfield says there are "very few cases" of true asymptomatic people - people who have been confirmed diagnosed with Covid-19 through a lab test, but don't display any symptoms at all.
"And to date there are no documented cases of asymptomatic transmission," he says, adding: "This does not exclude the possibility it may occur."
Regardless of the new transmission information, it's important for people to stick to the current precautions to reduce the chance of infection, Dr Bloomfield says.
It includes washing your hands frequently, keeping a two-metre distance from people and staying home if you're unwell.