Unlocking Conspiracy Belief Systems: How Fact-Checking Label on Twitter Counters Conspiratorial MMR Vaccine Misinformation.

This study tested whether a simple fact-checking label on Twitter effectively reduces vaccine conspiracy beliefs, misinformation engagement intentions, and vaccination intentions. A web-based experiment ( N = 206) of adults living in the United States through Amazon Mechanical Turk (MTurk) was conducted for the measles-mumps-rubella (MMR) vaccine in March 2020. The results showed that the fact-checking label attached to the conspiratorial misinformation post significantly reduced MMR vaccine conspiracy beliefs compared to the no fact-checking (misinformation-only) condition but did not directly affect MMR misinformation engagement intentions and MMR vaccination intentions. In addition, we found that the fact-checking label effectively decreased vaccine conspiracy beliefs and misinformation engagement intentions for those whose prior favorable attitudes toward MMR vaccination were relatively low. Based on our findings, we suggest that public health professionals and health communicators use the fact-checking label as a promising tool for countering conspiracy theories about vaccination. However, they should further seek alternative ways to limit the public's engagement in misinformation-related activities on social media and promote health protective behavioral intentions, given the limited effects of fact-checking labels.