The prospect of a massive US Government rescue package and moves by the Federal Reserve have lifted market sentiment but more volatility was certain, Zollner said.
"It's not a stimulus package, it's a survival package," she said.
Wall Street had its biggest market surge since 1933 last night.
"Of course 1933 was not a great year and markets were up and down and all over the place," Zollner said - as they are now.
Economists were modelling scenarios because forecasting was extremely difficult.
"I don't even know how StatsNZ is going to measure activity in this kind of environment," she said.
ANZ's base case was a rapid fall in GDP of 8-10 per cent because of the shutdown.
The Reserve Bank and Government had front-footed their response, which was good, she said.
In the short term the focus would likely stay on global credit markets as most economic data was historic.
The data was starting to show the impact, she said, noting bad manufacturing indexes released overnight, "We'll be watching global markets," she said. "Not so much equities, which are all over the shop, but measures of stress in credit markets are very important."
The key was that central banks managed to head those stresses off.
ALERT_STAGES
"You need the money and credit to keep flowing in the economy," she said: "Not so companies can rush out and invest, but just so that we can all get through this."
A new report from global research unit Morningstar also struck an optimistic tone this morning, while recognising that a complete economic recovery may take some years.
"We expect the Covid-19 impact to be severe in 2020, with global GDP growing 2 per cent below trend," Morningstar analysts said.
"However, we anticipate a vaccine ready to be deployed by mid- to late 2021, setting the stage for a return to normality and a quick recovery of the global economy in 2021."
The dramatic monetary and fiscal interventions announced by central banks and governments globally would provide "enormous tailwinds for the world economy to grow above trend and undo most of the damage by 2024".
