Since the COVID-19 pandemic hit the global community, politicians as well as scientists increasingly turn to Twitter to share urgent health information using various message styles. The results of our 2x2 between-subject experiment show that if a Tweet is written in lower-case letters, participants perceive the information source as more trustworthy. Furthermore, the information is perceived as more credible, and people are more willing to read the health information and share it via social media. Furthermore, scientists are perceived as possessing more expertise than politicians. However, politicians are perceived as possessing more integrity and benevolence than scientists.