It follows the arrival of the first quarantine free flight from New Zealand last week.
The government says so far all of the people who have tested positive for the virus were on the flight.
Premier Dalton Tagelagi is a close contact of one of the passengers and is in isolation at home.
Niue remains at Alert Level Yellow as there is no community transmission.
The government asks anyone with Covid-19 symptoms to get tested.
Photo file
