Table 1.

Identified keywords for the three dimensions of COVID-19 risk perceptions

Perceived Susceptibility (CHV Ontology ID)	Perceived Severity (CHV Ontology ID)	Negative Emotion (CHV Ontology ID)
Vulnerable/vulnerate Risk/risky Unsafe/not safe (ochv#37555) Suspect Doubt/dubious Hesitate/hesitating Danger/dangerous Unsure Believe/believed Undoubted/undoubting Confused/confusing/confusion Immune /immunity High risk/ high-risk At risk/ at-risk Avoid Cancel Postpone	Die Dead/death Lethal Fatal Pain/painful (ochv#9185) Isolate Judge Shame/shameful Suffer/suffering/suffered Paralyzed Restricted	Worse/worthen/worthening Worthened/worst Dread Fear/feared/fearful/fearing (ochv#37463) Scare/scared/scaring (ochv#51823) Outrage Nervous Panic Terrify/terrified/terrifying Worry/worried Anxious/anxiety Stress/stressed Distrust

Note: Laypersons’ words and phrases reflecting the risk perception were populated from standardized vocabularies. The identified keywords were confirmed by human experts, standardized by Linguistic Inquiry and Word Count (LIWC) and (Consumer Health Vocabulary) CHV, and enhanced in term of generalizability as some could be semantically linked to existing medical/healthcare vocabularies as identified by the Uniformed Medical Language System (UMLS). A complete ID in CHV ontology is http://sbmi.uth.tmc.edu/ontology/ [identical ID of a concept].