TUSCALOOSA, Ala. (AP) — An autism researcher at the University of Alabama is helping track social media use by people who publicly advocate against the use of vaccines.

Assistant psychology professor Theodore S. Tomeny and colleagues have used a computer algorithm to analyze almost 500,000 tweets over a five-year period that included the words “autism” and “vaccines.”

Their work found that such messages typically are associated with areas where people have annual incomes of $200,000 or more. They also are linked to places where there is a higher percentage of new mothers.

In Alabama, research found the strongest anti-vaccination sentiment was found along the Gulf Coast and around metro Birmingham.

Tomeny says the study isn’t meant to measure public opinion, but rather to take a snapshot of a “vocal minority” on social media.