WELLINGTON (Reuters) – More nations were flying medical staff and supplies to Samoa on Friday to battle a measles outbreak that prompted the Pacific island nation to declare a state of emergency this month, as the death toll rose to 42, most of them children younger than four.

A significant drop in immunisation over the last few years has made Samoa highly vulnerable to outbreaks of the disease, with the World Health Organisation (WHO) saying vaccine coverage is just about 31% there.

Schools have been shut and a mass vaccination effort launched in the nation of just 200,000 located south of the equator halfway between Hawaii and New Zealand, with its government saying 50,068 people have been vaccinated.

The health ministry said 3,149 cases of measles have been reported, with 213 during the last 24 hours. Of 197 victims in hospital, 20 are critically ill children and three are pregnant women, it added.

Deaths in the outbreak have now reached 42, the majority of them children under the age of four, the government said.

Neighbouring New Zealand said it was sending more supplies and personnel, including emergency medical assistance teams, nurse vaccinators, intensive care specialists and Samoan-speaking medical professionals.

“The Samoan health system is under serious strain with growing numbers of people, many of whom are very young, needing complex care as a result of the measles outbreak,” said New Zealand’s foreign minister, Winston Peters.

New Zealand would also fund 100,000 more vaccines for measles and rubella, Peters added in a statement.

Britain said a group of British doctors and nurses left on Friday to help Samoa’s efforts to rein in the outbreak, while Australia said it had also sent medical personnel and supplies.

Measles is caused by a highly contagious virus that spreads easily through coughing and sneezing.

Other nations in the Pacific, such as Tonga and Fiji, are also grappling with a spike in the number of measles cases.

Tonga has said its outbreak followed the return of a squad of its rugby players from New Zealand, where Auckland, the biggest city, is tackling a growing number of cases.

Measles cases are rising worldwide, even in wealthy nations such as Germany and the United States, as parents shun immunisation for philosophical or religious reasons, or fears, debunked by doctors, that such vaccines could cause autism.

(Reporting by Praveen Menon; Editing by Clarence Fernandez)