Director-General of Health Ashley Bloomfield said one of the people who tested positive works at an Americold food cold-storage facility in Auckland, which was being swabbed to check if it was possible source of the infections.
"We do know from studies overseas that actually, the virus can survive in some refrigerated environments for quite some time," he said.
Bloomfield said two of the people who had tested positive had traveled to the city of Rotorua while suffering symptoms over recent days and had visited several tourist attractions.
