Table A1.

Survey measures.

Construct	Measure
Outcome Variable
Vaccine Hesitancy	“When a government-approved vaccine for COVID-19 becomes available, I will get it,” rated a 5-point Likert-type scale (1 = strongly disagree, 2 = disagree, 3 = unsure, 4 = agree, 5 = strongly agree). We classified individuals as “hesitant to be vaccinated” if they answered 1, 2, or 3, and “intends to be vaccinated” if they answered 4 or 5, consistent with established definitions of vaccine intention and hesitancy [6].
Individual Level Determinants
Sociodemographics (7 items)	Age, gender, race/ethnicity, education, marital status, annual household income, work status.
Personal Risk Factors
Physical Health Status	“Do you currently have a chronic/serious health condition (yes/no)?” If “yes”, please specify.
Mental Health
General Depression (4 items)	PROMIS Depression 4-item Short form [22]
General Anxiety (4 items)	PROMIS Anxiety 4-item Short Form [22]
COVID-19 Preventive Measures
Social Distancing	“How often do you practice social distancing when you are with others who do not live with you?” (0 = never to 10 = all the time)
Mask Wearing	“How often do you wear a mask or other face covering when you go out in public?” (1 = never to 5 = all the time)
Hand Hygiene	“How many times per day do you wash your hands with soap and water for at least 20 s?” and “How many times per day do you use hand sanitizer?” (1 = 0 times, 2 = 1–3 times, 3 = 4–6 times and 4 = >6 times)
Social Cognitive Factors
Knowledge	8 items adapted from previously published studies [26,27,28] (e.g., “COVID-19 is spread through coughing and sneezing”, “People exposed to COVID-10 can spread the disease to others, even if they do not have any symptoms”, “Currently, there is no cure for COVID-19”). Response options were “true”, “false”, and “I don’t know.”
Attitudes	Ten items based on the HBM and TPB tapping vaccine attitudes were derived for this study. Questions were introduced by asking, “How important are each of the following in your decision about whether to get a government-approved COVID-19 vaccine when it becomes available?” All items were rated on a 5-point Likert-type scale (1 = not at all important to 5 = extremely important).
Perceived Susceptibility	“My personal risk of getting infected with COVID-19 if I do not take the vaccine.”
Perceived Severity	“How serious the COVID-19 outbreak is in the area where I live”
Cues to Action	4 items on the role of a national vaccine mandate and recommendations from government representatives, public health experts, and one’s healthcare provider in vaccination decisions.
Perceived Benefit	“Whether the vaccine is free of charge.”
Perceived Barriers	“Whether there are any known serious side effects of the vaccine.”
Subjective Norms	“Whether other people I know are being vaccinated.”
Perceived Control (Convenience)	“Whether the process for me to be vaccinated is convenient.”