The Government is currently grappling with how to kick-start the country's economy - including the tourism sector - once the lockdown is no longer needed.
More than half a million jobs have been salvaged so far through the Government's wage subsidy scheme, including tens of thousands of tourism jobs.
But Tourism Industry Aotearoa (TIA) chief executive Chris Roberts said the lights have already gone out on international tourism.
"It's effectively gone for the remainder of 2020 - potentially longer," he told the Herald.
"It could be potentially up to five years before we can rebuild international tourism."
The sector was expected to be worth $18b this year, or roughly 6 per cent of GDP, and it supports hundreds of thousands of jobs (there are about 400,000 workers in tourism, including domestic tourism).
The domestic tourism market is worth $6b a year more than the international market, and Roberts said that would be the focus in a post-lockdown New Zealand.
"It's clear that's where we can get some activity underway, and get some money through the tills of those tourism businesses from local Kiwis."
In time, border restrictions could be eased with countries that posed little risk of exporting a Covid-19 outbreak, he said.
"After lockdown is lifted and the virus is under control in New Zealand, there is no way international tourism will just switch back on.
"We don't know how bad this will get globally. The most likely scenario is that the border opens selectively to particular countries."
He said more international visitors came from Australia than any other country, so a relaxation of trans-Tasman border controls would be a huge boost to the tourism sector.