As the controversy continues, researchers reviewed studies and have come up with four different profiles for people who choose not to be vaccinated, along with strategies to convince them to do so.

These are the four individual personality types for people who chose to opt out of vaccination, the researchers say:

• Complacent: Those who do not care about immunization. The researchers recommend offering stronger information, like doctor’s views, or making vaccinations mandatory.

• Convenience: People who lack the willpower to vaccinate or face the inconvenience of cost and travel. The researchers recommend asking people to pre-commit, and sending phone or text reminders.

• Calculation: Individuals who weigh potential pros and cons of vaccination, and may not vaccinate when information is contradictory. Incentives for these people may be helpful.

• Confidence: Individuals who possess incorrect knowledge that distorts their perceived risk of vaccination and weakens their trust in vaccinations. According to the researchers, these people are the least likely to change their mind, and trying to do so may make them more adamant, so vaccine proponents should concentrate on the other three groups, they said.

The study appears in the journal Policy Insights from the Behavioral and Brain Sciences.