COVID-19: Why do people keep buying toilet paper, when we know it won't run out?

With Aotearoa launched back into COVID-19 alert level 4 after the discovery of the Delta variant in the community, panic buyers have once again been clearing shelves nationwide.

As panicked Kiwis flooded into supermarkets yesterday, toilet paper was piled high in people's trolleys.

It's a baffling pattern of behavior we've seen before - but why do people head straight for the loo roll when a lockdown is announced?

Dimitrios Tsivrikos, a lecturer in consumer and business psychology at University College in London says toilet paper has become an "icon" of mass panic in the COVID-19 world.

"In other disaster conditions like a flood, we can prepare because we know how many supplies we need, but we have a virus now we know nothing about," he told CNN.

"When you enter a supermarket, you’re looking for value and high volume."

He theorises that the large packaging toilet paper is found in could contribute to why people go for it. 

Another expert says it's partially stress-related.

Sander van der Linden, an assistant professor of social psychology at Cambridge University, told CNN stress hinders people's reasoning skills.

"They look at what other people are doing. If others are stockpiling it leads you to engage in the same behaviour," he said.

"People see photos of empty shelves and whether it's rational it sends a signal to them that it's the thing to do."

Regardless of why people do it, multiple Kiwi authorities are pleading with the public not to. 

Supermarkets urged shoppers to "keep calm and kind" after New Zealand's first community COVID-19 case in 170 days prompted a flurry of panic buying on Tuesday afternoon.

Antoinette Laird, head of corporate affairs at Foodstuffs - which supplies New World, PAK'nSAVE and Four Square supermarkets - says while a potential lockdown is "unsettling", there are plenty of groceries on the shelves.

Jacinda Ardern has repeatedly said supermarkets, pharmacies, and other essential businesses will remain open and stocked no matter what alert level the country is at.

"Those providers... will all be open and continue to be open."