UC Davis

Health misinformation on social media has consistently posed harms to public health efforts especially in the topic of vaccination. Vaccine misinformation has contributed to the delay and refusal of routine and possibly Covid-19 vaccinations. Studies have mainly been focused on reduction of misperceptions as an outcome of health misinformation corrections. However, vaccination intention and its predictors, such as attitude towards vaccination, perceived vaccine effectiveness, and vaccine safety concerns, are more important outcomes to be tested as they contribute to the actual vaccination uptake. Therefore, this dissertation takes the initiative on investigating what correction methods are the most effective and why, how corrections work in mitigating the harms brought by misinformation on vaccination intention, and whether corrections would have similar effects on real social media platforms. The first study investigated the effects of two-sided refutational messages on vaccination intentions. Results showed that two-sided refutational messages increased vaccination intentions through increasing positive attitudes towards vaccines in comparison to corresponding misinformation messages. This study showed that the effects of correction did not backfire as participants with different levels of conspiracy beliefs had the same correction outcomes. The second study tested whether falsification labels had effects on correcting attitude and perceived harms of vaccines, what were the most effective sources to correct and why. Results showed that all falsification labels increased attitude toward vaccination and lowered perceived harms of vaccines. It also revealed that both medical institutions and research universities were more effective sources to correct misinformation, as they had higher perceived source expertise on vaccines. This study found that correction effects were significant among participants with high and medium levels of conspiracy beliefs. The last study has combined the correction strategies of both studies one and two and shifted the correction environment onto Twitter. This online field experiment explored whether corrections with falsification labeling, sources, and correction explanations could mitigate the harms of misinformation on vaccination intentions among flu and Covid-19 vaccines through attitude, perceived vaccine effectiveness, and vaccine safety concerns. The findings showed that the utilized correction methods increased flu and Covid-19 vaccination intentions through increasing positive attitude. Moreover, correction effects were significant only among participants with the highest level of conspiracy beliefs. This last study showed corrections are effective on social media and could be used to target more vulnerable populations.