Edwin Tamasese was charged with incitement against a government order after he was detained on Thursday.
The outbreak - which has killed at least 63 people, mostly young children, since October - is in part blamed on people spreading false information, claiming vaccinations are dangerous.
Samoa declared a state of emergency, and made vaccinations compulsory.
Mr Tamasese had spoken out against vaccines on Facebook, instead promoting using ineffective remedies such as papaya leaf extract to treat the deadly illness.
Before his arrest, he had described the government's mass vaccination programme as "the greatest crime against our people", and falsely claimed vitamin C could cure the infected children.
Samoa's low vaccination rates are in part due to the deaths in 2018 of two children wrongly being attributed to vaccination against measles, mumps and rubella.
However, their deaths were due to nurses mixing the vaccine with a muscle relaxant instead of water, and not the vaccine itself.
The cases had nonetheless raised local fears, and were exploited by people seeking false proof that vaccines are harmful.
The current crisis in Samoa has also triggered many foreign anti-vaccination campaigners to weigh in and criticising the country's drive to immunise its children, which is trying to lift the level of measles vaccination coverage to more than 90%.