Nearly 1000 Countdown staff are off work because of Covid-19 and the company says that means it is having to change how it operates - and what's on the shelves may change, too.
Staff are either isolating because they are infected or are a household contact, with staffing at the two distribution centres in Auckland down 45 percent while stores in the city have about 10 percent of workers away.
The company said it was expecting the number of affected employees to grow and that many of its suppliers, growers and manufactures had also been hit, with a particular impact on butchers, forklift and truck drivers.
There have been gaps on supermarket shelves with some stores running low on toilet paper, potato chips and frozen food.
Countdown corporate affairs, safety and sustainability Kiri Hannifin said the key thing is that there was plenty of food and groceries to go around.
"It's just taking longer to get through. Please bear with us.
"As has been the case with supply chains around the world dealing with Omicron, this kind of disruption to the workforce is hard to manage, but we're doing our best and bringing on temporary team members where we can, keeping up our recruitment and we've also seconded team from our support offices too.
"With fewer team members available to work across the network, we're prioritising getting key lines and essentials into our stores, so customers may not always see their favourite brands or products. We're also changing how we operate in some stores and distribution centres, by doing things like temporarily shifting team around to support critical areas and reducing hours if we need to."
In addition, fewer delivery slots were available for online orders and supply chain issues would mean more substitutions in orders, too.
"Our team is doing their best to ensure our customers, particularly those who are staying at home and isolating, get what they need, but it is challenging at the moment," Hannifin said.
Rapid antigen tests will also be available at Countdown pharmacies this week.
"These will retail at $32.99 for a five-pack. We have a limited supply of RATs for sale at the moment as we have focused on having tests available in critical parts of our supply chain first, but we'll be selling RATs in more stores as they come through from our suppliers."