Jacinda Ardern talks about her meeting with Rotorua tourism operators affected by coronavirus. (Video first published on March 19, 2020)

Deputy Prime Minister Winston Peters has confirmed that "locking down" New Zealand is a possibility if community transmission of coronavirus begins, as health officials acknowledge stronger actions will be needed to save lives.

Peters, speaking to reporters on Thursday afternoon, said all possible decisions were being looked at by the Government, and "lockdown is a possibility" when the evidence suggested it needed to occur.

Asked if lockdown would come when New Zealand has community spread of the virus, he said: "Yes".

KEVIN STENT/STUFF Deputy Prime Miniser Winston Peters has said "locking-down the country was a possibility if Codi-19 reached community transmission. (file photo)

On Thursday, rumours of an imminent shutdown of schools and other public places in New Zealand were widespread. Prime Minister Jacinda Ardern quashed the rumours, saying Kiwis must prepare but not panic.

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But the Government does appear to be moving away from the "flattening the curve" strategy, which tries to minimise the burden on the health system by reducing transmission through self-isolation of confirmed and potential Covid-19 cases.

ALDEN WILLIAMS/STUFF A hospitality worker wears a face mask at The Greedy Cow Cafe in Tekapo. (file photo) File generic coronavirus

Recent modelling, in a study published by London's Imperial College, has shown that mitigation strategies — which include self-isolation of cases and social distancing of elderly and those vulnerable to the virus — would still see the virus overwhelm health systems and would only reduce deaths by half.

"Suppression" of transmission was recommended. This required the social distancing of the entire population, self-isolation of cases and households, and the closure of some schools and universities.

The clamp downs may be lifted when transmission eases, and then return when the virus begins to spread again.

MONIQUE FORD / STUFF Ministry of Health director-general Dr Ashley Bloomfield says they are looking at trying to contain Covid-19 as a "series of spikes".

Such measures would be needed for 12 to 18 months, roughly until a vaccine was expected to be produced, the study said.

Minister of Health David Clark said he had received advice on the study, and Cabinet was considering how it could be implemented.

He said the advice was "in line with the strategy that we've been taking that we contact trace all cases and don't get widespread outbreaks", and was considered when banning indoor gatherings of more than 100 people on Thursday afternoon.

ROBERT KITCHIN/STUFF Education Minister Chris Hipkins says schools may be clsoed as Covid-19 spreads.

He did not directly answer a question about planning for a lockdown.

"We are going to take the advice as we receive it. Right now, the advice that we have, is that the internal events of 100 or more should be cancelled," he said.

Ministry of Health director-general Dr Ashley Bloomfield has said health officials were looking at trying to contain the virus in a "series of spikes", in light of the modelling, instead of having a flat curve of cases.

"We want to act before we see evidence of widespread of community outbreak," he said at a press conference on Thursday.

"What we're planning for is a long-term effort here, because if we manage to successful prevent community transmission here in New Zealand, but there are other countries that have cases still, we can't keep ourselves locked-down for a year."

New Zealand does not have community transmission of Covid-19. There were 28 confirmed cases on Thursday, all linked to overseas travel.

He said "flattening the curve" would still have an influx of patients that would overwhelm a health system two or three times the size of New Zealand's.

"Our aim is to stop it getting to that point, where the peak is higher than our health system's ability to cope," he said.

"We're preparing to take all the measures we need to make sure we don't get wider community spread ... We have shown that we are prepared to act early."

Education Minister Chris Hipkins, responding to questions in the House, said school closures would occur in proportion to the spread of Covid-19.

Individual schools that had positive cases would close, and a greater number of schools may close if community outbreaks occur.

Bringing the school holidays forward to create some "breathing space" was an option on the table, he said.