SUMENEP, Indonesia (AP) — Three health care workers rode motorbikes into the Indonesian city of Sumenep, carrying doses of measles vaccine and a list of children who needed them. With blue medical boxes in hand, they went from house to house administering the life-saving shots.

The health workers on wheels are part of the regional government’s latest efforts to curb a deadly measles outbreak on Madura Island that has persisted for the past nine months. More than 2,600 children have already been infected this year and 20 have died.

But efforts to stop the outbreak from spreading through the predominately Muslim population are being hindered in part by concerns that some measles vaccines may not meet Islam’s halal standards because they use a stabilizer that is derived from pigs.

Pork-derived gelatin is widely used as a stabilizer to ensure vaccines remain safe and effective during storage and transport, presenting a dilemma to religious communities that view pigs as ritually unclean. Many Islamic scholars say that vaccines with gelatin stabilizers can be used under religious law, as can other medical products with pig-derived ingredients, under certain conditions.

Indonesian religious leaders ruled in 2018 that vaccines with pig gelatin are haram, or forbidden, but advised Muslims that they should be used until other shots are available “for the benefit of society,” said Ahmad Syamsuri, the head of Disease Control and Prevention at the Sumenep Health Office.

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Parents wait for their children during a measles vaccination campaign following an outbreak, at a kindergarten in Sumenep on Madura Island, Indonesia, Monday, Sept. 8, 2025. (AP Photo/Dita Alangkara)

Parents wait for their children during a measles vaccination campaign following an outbreak, at a kindergarten in Sumenep on Madura Island, Indonesia, Monday, Sept. 8, 2025. (AP Photo/Dita Alangkara)

In Sumenep, many are reluctant to even discuss their religious concerns.

Pujiati Wahyuni, a 31-year-old Muslim mother and nurse, knows parents who refuse the vaccines for their children on religious grounds, though she recently had her daughter receive the vaccine at an Islamic kindergarten in Pamolokan village.

“Yes, there are some. Islam is a big religion. Maybe some Muslim people just do not want to get vaccinated, and it is not just now, but since they were born,” Wahyuni said.

The regional government’s latest efforts began in August and include making more than 78,000 vaccines available to children in the region, which are distributed through local clinics, delivered directly to the residents at their homes and even brought to schools.

The hope is that the campaign will help prevent future outbreaks, infections and deaths. But they cannot compel reluctant parents, said Musthafa, the general secretary of Indonesian Ulema Council in Sumenep.

“We have high hopes for Muslims in Indonesia, who are the ones consuming it. Let us ask the government, in this case the Health Office and the Ministry of Health, to find a halal vaccine,” said Musthafa.

Indonesia, the world’s largest Muslim-majority nation, has reported previous outbreaks of measles, mostly driven by gaps in vaccination coverage.

In 2018, a major outbreak of the highly infectious disease occurred in the easternmost province of Papua, causing dozens of deaths. Due to some vaccine hesitancy then, the Indonesian Ulema Council said the measles-rubella vaccine, produced by the Serum Institute of India, contained an ingredient derived from pigs but allowed its use until a halal alternative was available.

The Serum Institute declined The Associated Press’ request for comment.

A health worker shows a vial of measles-rubella vaccine during a vaccination campaign in Sumenep on Madura Island, Indonesia, Monday, Sept. 8, 2025. (AP Photo/Dita Alangkara)

A health worker shows a vial of measles-rubella vaccine during a vaccination campaign in Sumenep on Madura Island, Indonesia, Monday, Sept. 8, 2025. (AP Photo/Dita Alangkara)

Globally, the World Health Organization says 84% of children received the first dose of measles vaccine last year, and 76% had received two doses. But experts say measles vaccine rates need to reach 95% to prevent outbreaks. WHO noted that 60 countries reported big measles outbreaks last year.

Measles vaccination rates in Indonesia fell below the country’s targets in 2023, according to data from the Ministry of Health. In 2023, measles-rubella vaccinations reached 86.6% of the target, and in 2024, the number fell to 82.3%.

From May to July — the peak of the outbreak in Sumenep — isolation rooms at regional hospitals were full as staff treated over a hundred measles cases daily.

Medical staff stand at an isolation ward for measles patients at Moh Anwar Hospital in Sumenep on Madura Island, Indonesia, Wednesday, Sept. 10, 2025. (AP Photo/Dita Alangkara)

Medical staff stand at an isolation ward for measles patients at Moh Anwar Hospital in Sumenep on Madura Island, Indonesia, Wednesday, Sept. 10, 2025. (AP Photo/Dita Alangkara)

At an Islamic kindergarten in Pamolokan village, the head of the community health center met the students’ mothers before vaccines were administered and urged them to protect their children by reducing the spread of measles in Indonesia.

Despite her hesitation over the vaccine’s ingredients, Ayu Resa Etika, 28, from Kebunan village, finally allowed her 2-year-old son to get his delayed second dose after seeing many local children hospitalized with measles.

“There is a little doubt because it is not halal. But despite all that, this is for the sake of the child’s health,” Etika said. “The effects are quite extraordinary; it can cause death. I am afraid that if my son is not vaccinated against measles, that is the risk. So it’s OK, as long as the effects are good.”

Associated Press writer Aniruddha Ghosal in Hanoi, Vietnam, contributed to this report.

Associated Press religion coverage receives support through the AP’s collaboration with The Conversation US, with funding from Lilly Endowment Inc. The AP is solely responsible for this content.