People hoping to get a late-night or early-morning supermarket shop in might be out of luck as a number of Countdown stores are reducing their hours.

Countdown announced a nationwide reduction of its opening hours and some Auckland stores are temporarily closing due to the strain of increased demand during the Delta outbreak lockdown.

The supermarket chain's central Auckland Metro stores in Albert St and Halsey St were set to temporarily close from Sunday, August 22.

This was to allow teams from these locations to provide support in other larger stores that were seeing increased demand since the lockdown began, Countdown said in a statement.

Trading hours across Countdown stores nationwide would also change to 8am to 9pm to give teams time to restock shelves and meet the high levels of demand being seen across the network.

Four Auckland stores would further reduce their trading hours due to having team members isolating after store visitors tested positive for Covid-19. The stores are: Countdown Lynfield (8am-6pm), Takapuna (8am-6pm), Lincoln Rd (9am-6pm) and Botany (9am-6pm).

Countdown's general manager corporate affairs, safety and sustainability Kiri Hannifin said while the store closures would be frustrating for some customers, it's a reality of the environment that many essential services were operating in.

"A number of our stores are locations of interest and our team are isolating, which we absolutely support.

"At the same time, we're looking at how we can best allocate our team across our stores to ensure we're also keeping our communities fed.

"This may mean further stores close or reduce their hours as all our teams pull together to help out," Hannifin said.

Staff would also be paid a 10 per cent bonus in recognition of the "essential role they played keeping Kiwis safe and fed" in alert level 4 lockdown, Countdown said in its statement.

Hannifin said Countdown was also continuing to work closely with the Ministry of Health and local DHBs to roll out the vaccine to their teams as quickly and safely as possible.