A crew member of the US Navy hospital ship sent to New York City to help relieve hospitals during the coronavirus outbreak has tested positive for the disease.

The USNS Comfort crew member tested positive on Monday and is being isolated, according to a Navy statement. The positive test will not affect the hospital ship's overall mission to receive patients.

The Comfort has only treated about 40 non-Covid-19 patients since arriving in the city last week, prompting complaints it was doing little to help overburdened hospitals in the area.

President Donald Trump said on Monday that he agreed to take Covid-19 patients aboard the ship after speaking with New York Governor Andrew Cuomo.

Governor Cuomo announced his intention to ask the president to change the ship's mission during his daily briefing on Monday.

Federal officials say emergency patients will now be seen on the ship, whether or not they have the virus, though the ship can only isolate only a small number of patients.

In Tuesday's press briefing, Governor Cuomo said that the capacity of the ship would drop to 500 patients in order to appropriately isolate those being treated.

On Monday, New York City had 68,776 cases and 2,738 deaths out of statewide totals of 130,703 cases and 4,758 deaths.