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Market research company IRI has released figures for the week ending March 1 which showed a 14 percent increase for the week on the year before.
Managing director Craig Irwin said in the three days from the confirmation of the first case, sales increased $38 million more than the same week last year.
"It's in the obvious categories that you would have expected, right - so, toilet paper, water, even dietary supplements.
"Some of those categories are up 20, even 50 percent.
"This at the moment is the fifth-biggest week of the year and the only other weeks that beat it are the four weeks around Christmas and there's no other reason that this should be up that high other than the impact of of the panic buying," Irwin said.
The increase in confirmed coronavirus cases was likely to cause the trend to continue for the next few weeks, he said.
Research Company Nielsen's data showed a similar pattern. Executive director of retail Lance Dobson said health and hygiene, staple foods, and household emergency products were the top picks - with a massive 95 percent increase in rubber gloves sales.
"It's products like hand wash, it's antiseptic liquid, household cleaning products, disinfectant.
"We also saw quite a big spike in rubber gloves for shelf stable foods.
"It's things like rice, flour, canned food, and then we're also seeing toilet paper and, strangely, candles and matches also seeing quite a big lift."
The increase in ingredients and pre-prepared meals was great for supermarket and food retailers, but Irwin suspected it was not so good for the hospitality industry as people chose to dine at home.
"Hearing from restaurateurs where they're saying numbers are down and if you look at that and our numbers and look at what is being purchased in the grocery store you can start to join those two together and go 'well, people are deciding maybe not to go out into the public places where they are with a large group of people," Irwin said.
People on the streets were not too concerned, and had not been adding anything extra to the trolley. One said that, if it came to it, he could go without toilet paper for a couple of days.
Cottonsoft has been trying to prevent exactly that. In a statement, the toilet paper producer and distributor said its production plants in Dunedin and Christchurch were extending their hours to keep up with demand.
"The recent unprecedented panic buying of toilet paper has resulted in many retailers seeing empty shelves, resulting in many households being deprived of the ability to purchase essential household commodities, however toilet paper seems to have borne the brunt of this impact."
Cottonsoft said it would be limiting the range of products it made, to ensure availability of toilet paper.