A measles outbreak on Indonesia's Sumba Island has killed five children and sickened 711 other children, UNICEF said Thursday.
The U.N. children's agency, along with the World Health Organization and the government, had launched a vaccination campaign to contain the deadly virus. It also is planning to vaccinate as many as 200,000 children on the island between the ages of 6 months to 15 years old, said John Budd, a spokesman for UNICEF.
The island is located about 1,000 kilometers (621 miles) southeast of the capital Jakarta.
Budd said the cause of the outbreak appeared to be low immunization rates among children on the island. It remains unclear when the first cases were reported.
"There are areas, pockets if you like, particularly in more remote areas where the immunization rates have dropped, which makes children far more vulnerable to preventable disease like measles and polio," he said.
Measles is one of the most highly contagious viruses, and in the developing world kills between 3 percent and 5 percent of the children who get it.
There have been several outbreaks of measles in Indonesia over the last few years because most children have not been vaccinated. Nationwide vaccination rates for measles is about 70 percent, according to the WHO, but rates in poor and remote areas in the vast archipelago can dip to as low as 10 percent.
Vaccinating people living in a ring in neighborhoods or villages surrounding a case usually shuts down transmission very effectively and drastically reduces the severity of any cases that slip through. Patients are not contagious during the 12 days they are incubating the disease, which spreads through coughing and sneezing.
The measles outbreak, Budd said, comes at a difficult time for the country's overextended health system, reports the AP.