The government of Samoa will shut down for two days this week while officials try to curb a deadly measles outbreak that has sickened 3,728 and killed 53—48 of whom were children ages 0 to 4 years old.

The Pacific island nation of around 200,000 first declared an outbreak of measles on October 16. The highly contagious viral infection spread rapidly, and officials declared a state of emergency by mid-November. The outbreak has continued to flare, however. On Sunday, the government reported that there had been 198 new measles cases in the last 24 hours alone.

In response, officials there have closed schools, barred children from public gatherings, and begun an intensive vaccination campaign. Since November, the government has reported vaccinating over 58,000 people.

But officials have their work cut out for them. The World Health Organization and UNICEF estimated that Samoa’s measles vaccination rate for infants was just 31% in 2018. That’s down from about 60% to 70% in earlier years and a high of 90% in 2013.

The drop may be partly explained by the tragic deaths of two infants in July 2018, according to the WHO. The infants died on the same day at the same hospital, shortly after they had each received what was supposed to be an MMR vaccine (which protects against measles, mumps, and rubella).

While some quickly blamed the vaccine itself, officials later determined that two nurses had improperly prepared the immunizations. Investigators found that they had mixed in a lethal dose of muscle relaxant, and one of the nurses tried to cover up the error by taking the empty bottle of the muscle relaxant home after retrieving it from the garbage. The two faced charges of manslaughter and were both sentenced to five years in prison in August of this year.

Still, news of the heartbreaking deaths shook the island nation’s confidence in the healthcare system. And anti-vaccination groups pounced on the circumstances. Most notably, the deaths were picked up by the Children’s Health Defense, run by the prominent anti-vaccine advocate Robert F. Kennedy Jr. As The Washington Post noted, Kennedy’s organization spent months highlighting the deaths on Facebook while questioning the safety of the MMR vaccines. But the organization did not correct the posts or update its audience with information regarding the nurses’ error and convictions.

Kennedy visited Samoa in June, appearing alongside local anti-vaccine advocates and even a staff member of the US embassy. In November, Kennedy’s organization sent a letter to the Samoan prime minister, encouraging officials to question the MMR vaccine. Kennedy peddles the false and dangerous claim that vaccines are linked to autism, despite the fact that numerous scientific studies have robustly debunked the baseless claim.

On Sunday, Samoan Prime Minister Tuilaepa Sailele Malielegaoi encouraged residents to fight back against misinformation. “Let us work together to encourage and convince those that do not believe that vaccinations are the only answer to the epidemic,” he said.

At the same time, he announced that all government services will be closed from Thursday, December 5, to December 6 so that public servants could carry on with the mass vaccination campaign.