Foodstuffs New Zealand head of corporate affairs Antoinette Laird said some of its stores in the North Island sell ready meals, sandwiches and muesli pottles which are produced by LSG Sky Chefs.
The products have been removed from the shelves out of an "abundance of caution" until more is known about the source of the recent community cases, she said.
A spokeswoman for LSG Sky Chefs said it provides food for train services out of its Christchurch facility.
A KiwiRail spokesman said it uses LSG Sky Chefs catering for its "scenic services" out of Christchurch.
Due to the change in alert levels, the services are currently suspended until further notice due to social distancing challenges, he said.
"When services resume we'll work with LSG to ensure the safety of our team and passengers."
The LSG Sky Chefs spokeswoman said its Auckland catering operation is up and running, both for airline and retail customers, except for the laundry area.
"We only provide laundry services to airlines, so this does not affect our retail business.
"As a matter of principle, we are not talking about individual details of customer contracts and hence cannot reveal any customer names in this matter. Thank you for your understanding."
The woman who tested positive for Covid-19 was one of several LSG Sky Chefs employees who missed a scheduled test at the start of the month.
Although not mandatory, the woman, one of three people who tested positive during the weekend, had been part of a group of staff the catering company decided to test regularly as a "precautionary measure".
But, she was away on annual leave on February 1 when the tests were last done.
Covid Response Minister Chris Hipkins told Newstalk ZB he wasn't sure how many other staff had missed the test but all have since been tested again in the past 48 hours.
He said often on a public holiday regular testing can occur either the day before or after the holiday, but he wasn't sure if that had occurred at LSG Sky Chefs.
"I don't know have that information. We've asked them to have a look at that."