New Zealand has reported its first coronavirus-related death, a woman in her 70s on the west coast of South Island.

The woman, who authorities said had underlying health conditions, was reportedly diagnosed with influenza on admittance to hospital.

New Zealand health officials confirmed new 63 cases on Sunday – a drop from the increase of the previous two days – with the overall number of coronavirus cases standing at 514, said the director general of health, Ashley Bloomfield. Nine were receiving hospital care and one other was in intensive care on a ventilator.

The prime minister, Jacinda Ardern, said her thoughts were with the woman’s family. “Today’s death is a reminder of the fight that we have on our hands,” she said. “It also brings home exactly why we are taking such strong measures to stop the spread of this virus.

“Everyone can play their part through the simplest of tasks by not having contact with people outside of your bubble. Stay at home. Break the chain and save lives.”

New of the death came on day four of a government-ordered lockdown.

Bloomfield said New Zealanders could no longer be in any doubt as to the seriousness of the pandemic, “particularly for older people, and those with underlying pre-existing health conditions”.

In the case of the woman who died, as hospital staff had not been wearing the right protective equipment for a Covid-19 case, 21 workers had to be placed into self-isolation.

Of the people infected, 56 had recovered, according to the government. Ardern said this did not mean New Zealand was out of the woods.

“We’ve had discussion over what it is our case numbers might be telling us at present. None of us are willing to draw any conclusions at this early stage,” she said. “We must remember that there is a considerable lag time in any of our results.

“So we all need to be vigilant. No one can be complacent.”

Bloomfield said the opportunity to be lifesavers was right in front of everyone. He quoted Wellington hospital intensive care specialist Dr Paul Young: “If New Zealand pulls together as a community and stays at home, you will save more lives than I will in my entire career”.