Getting on top of this outbreak quickly will be key to preventing wider spread.

Otago University infectious diseases expert David Murdoch is applauding the Government for its swift response.

He told Mike Hosking we're learning from overseas what not to do.

"We're seeing clearly in Victoria but there are other places that have had explosive outbreaks and they have been linked to delays in response, so I think the vigorous response is absolutely the right thing to do."

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