NSW's last coronavirus patient has been discharged from hospital, with four coronavirus patients in the state now cleared of the disease.

NSW Health's executive director of health protection Jeremy McAnulty said it was "terrific news".

"NSW Health is extremely proud of its medical response to date with prompt, expert care to all patients, a comprehensive screening program and extensive information campaign," Dr McAnulty said.

Scientists at NSW Pathology used samples from NSW patients to cultivate and map the virus.

Australia's number of confirmed cases has remained at 15, while another 15 Australians on board a cruise ship docked in Japan have also contracted the virus. More than 220 Australians on the ship remain in quarantine.