The death toll in Samoa's measles outbreak continues to climb, with a majority of children aged under five among the 53 people dead.

Samoan authorities will shut down the country's government and re-purpose the country's public servants in an effort to fight a deadly measles outbreak.

The death toll reached 53 on Monday, when Prime Minister Tuilaepa Sailele Malielegaoi announced the last-gasp measure.

The Samoa Observer reports all government branches, save for water and power utilities, will close as of Thursday, with workers deployed on vaccination efforts.

The government has already declared a state of emergency, mandating immunisation for children as they seek to overcome low immunisation rates.

On Monday, officials announced a further nine deaths in the past 48 hours.

Of the 53 killed, 48 were children who hadn't reached their fifth birthdays.

Almost two per cent of the population - 3728 people - has caught the disease in the outbreak, which had origins in New Zealand.

Measles is a highly contagious virus, but preventable through an immunisation commonly administered twice in childhood.

Samoa's rock-bottom coverage made this tragedy both heartbreakingly preventable and predictable.

World Health Organisation data shows vaccination rates of children dropped from close to 90 per cent five years ago - close to herd immunity levels - to around a third today.

While New Zealand and Australian aid is hitting the ground, the nature of the disease's spread makes the arrival of vaccinations something of a damage control exercise.

New Zealand Prime Minister Jacinda Ardern pre-empted a growing death toll, listing a 54-strong Kiwi medical contingent on the ground on top of funding and medical supplies her country had delivered.

"We're doing all we can to support Samoa," Ardern said on Monday.

"Health authorities do tend to track the curve of infection. They'll be doing that in Samoa and it means sometimes things can be worse before they are better."

Samoa reports that 58,150 immunisations have been delivered since the start of a mass-vaccination campaign a fortnight ago.

It will not stop the death toll from rising.

For more than a week, roughly 200 new cases have been declared each day.

A Stuff report in Samoa states that 19 critically ill children have been admitted to hospital in the past day, along with two pregnant women.

Children are being urged to get vaccinated and to stay home and avoid contact with other children as authorities do their best to limit the disease's deadly spread.

New Zealand has also provided ICU specialists, Samoan-speaking doctors and nurses and oxygen generators to help local health systems, which have been pushed well beyond capacity.