Police and official agencies are now hunting for a person who attended a gym session at the same time a student infected with Covid-19 worked out during last month's Valentine's Day outbreak.

The Ministry of Health has revealed today some 6,000 contacts required to be tested and self-isolate during the February outbreak there is still one person who has evaded authorities.

But a gymgoer is now the only person that remains unaccounted for after the 21-year-old, known as Case M, worked out at City Fitness Papatoetoe in Hunter's Plaza in South Auckland in the hours after he took a Covid test.

Health officials later revealed the student, who studies digital technology at Manukau Institute of Technology, visited the gym twice while infectious, on February 20 and 26.

Today health officials revealed police and other agencies had been asked to find and test the person.

"One person from the gym remains outstanding and health staff are working with other agencies including police to try and contact this person, said the health ministry.

In the meantime the nearly 6,000 people who did the right thing and came forward for testing were praised for their actions.

"We do wish to thank all members of the community who did the right thing in order to keep the community safe," said the ministry.

The Valentine's Day cluster currently sits at 15 cases, comprising four families connected to Papatoetoe High School.

The initial mystery of how the student contracted Covid sparked a week-long alert level 3 lockdown in Auckland.

It was later revealed the student's mother and another mother took a walk where the infection was contracted during an earlier three-day snap lockdown at the start of the outbreak.

Health authorities are still unclear how the first family contracted the virus, with no clear link to an existing case at the border despite an exhaustive probe.