The vessel, Coral Islander, arrived Friday and the Department of Health team boarded to carry out coronavirus tests for the crew.
One of the 20 crew members yielded a positive result for coronavirus.
The Coral Islander sailed from Japan and called into New Caledonia, Solomon Islands, Fiji and Tonga before it arrived in Pago Pago.
An epidemiologist Dr. Aifili John Tufa said the two health department personnel who carried out the tests and the administration pilot who guided the vessel into port were now in isolation.
This is the second ship with coronavirus infected crew members on board to arrive in Pago Pago.