Acceptance of COVID-19 Vaccination Among Health System Personnel

Daniel J. Parente; Akinlolu Ojo; Tami Gurley; Joseph W. LeMaster; Mark Meyer; David M. Wild; Reem A. Mustafa

doi:10.3122/jabfm.2021.03.200541

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Appendix Figure 1.
Vaccine acceptance as a function of respondent order. The proportion of respondents reporting early (<3 months), late (>3 months), and never vaccine acceptance within 500-participant rolling windows is shown. Earlier respondents seem on the left while later respondents seem on the right. Rolling averages are compared with the whole-sample averages (solid lines). Vaccine acceptance patterns remain essentially stable as a function of respondent order, which is consistent with – but does not definitively establish – the absence of strong nonresponse bias.

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Table 1.

Respondent Characteristics; (n = 3347)

Characteristic	N (%)^*
Age, years
18 to 24	437 (13.1)
25 to 34	974 (29.1)
35 to 44	709 (21.2)
45 to 54	565 (16.9)
55 to 64	520 (15.5)
65 years or greater	142 (4.2)
Sex
Men	726 (21.8)
Women	2601 (78.0)
Other	7 (0.2)
No response	13
Race
American Indian or Alaska Native	6 (0.2)
Asian	125 (3.8)
Black or African American	104 (3.1)
White	2912 (87.6)
Native Hawaiian or Other Pacific Islander	4 (0.1)
Other	79 (2.4)
Multiple	95 (2.9)
No response	22
Hispanic, Latino, or Spanish Origin
Absent	3170 (95.4)
Present	152 (4.6)
No response	25
Educational attainment
Some high school or less	3 (0.1)
High school graduate	59 (1.8)
Some college	398 (11.9)
College graduate	1467 (43.9)
Master's degree	696 (20.8)
Doctorate or professional degree	716 (21.4)
No response	8
Clinical role
No clinical responsibilities	844 (25.6)
Attending physician	247 (7.5)
Fellow or resident physician	79 (2.4)
Advanced practice provider (APRN, PA)	118 (3.6)
Licensed nurse (RN, LPN)	491 (14.9)
Clinical pharmacist or pharmacy staff	81 (2.5)
Physical, occupational, or speech therapy	117 (3.5)
Unlicensed care aid	48 (1.5)
Case management or social work	32 (1.0)
Technician (radiology, EKG, lab draw, etc)	76 (2.3)
Clinical laboratory or clinical pathology	52 (1.6)
Administrative or support staff	300 (9.1)
Medical student	227 (6.9)
Nursing student	82 (2.5)
School of health professions student	153 (4.6)
Other student	34 (1.0)
Other	316 (9.6)
No response	50

APRN, advanced practice registered nurse; PA, physician assistant; RN, registered nurse; LPN, licensed practical nurse; EKG, electrocardiogram
↵* Percentages refer to all respondents (excluding “no response”) for each item.

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Table 2.

Intentions, Barriers, and Facilitators Associated with SARS-CoV-2 Vaccination (n = 3347)

Variable	N (%)^*
If a vaccine for novel coronavirus (COVID-19) receives Food and Drug Administration (FDA) approval, when do you intend to become vaccinated?
Within the first month of approval	1241 (37.2)
1 to 3 months after approval	744 (22.3)
4 to 6 months after approval	379 (11.4)
7 to 12 months after approval	231 (6.9)
More than 1 year (12 months) after approval	410 (12.3)
I do not intend to be vaccinated	331 (9.9)
No response	11
Which of the following concerns influence your decision to delay vaccination or to not receive vaccination?^†
Long-term side effects of the vaccine	1197 (57.1)
The vaccine will not be safe	1152 (55.0)
The vaccine will not be effective	777 (37.1)
Risk of vaccination is more than the benefit	650 (31.0)
The vaccine will be too expensive	255 (12.2)
I may be allergic to the vaccine	234 (11.2)
Short-term side effects (painful injection, muscle pain, feeling unwell the day of the injection, etc.)	159 (7.6)
Personal religious, moral or ethical reasons	154 (7.4)
The vaccine will give me novel coronavirus (COVID-19)	100 (4.8)
I will not have time to get the vaccine	79 (3.8)
Already been infected with novel coronavirus (COVID-19)	48 (2.3)
Other	303 (14.5)
No response	24
How concerned are you about becoming infected with novel coronavirus (COVID-19)?
Extremely concerned	532 (15.9)
Moderately concerned	1195 (35.7)
Somewhat concerned	835 (25.0)
Slightly concerned	554 (16.6)
Not at all concerned	228 (6.8)
No response	3
In general, would you say your health is:
Excellent	948 (28.4)
Very good	1651 (49.4)
Good	641 (19.2)
Fair	95 (2.8)
Poor	6 (0.2)
No response	6

↵* Percentages refer to all respondents (excluding “no response”) for each item.
↵† Queried of all persons not reporting intention to become vaccinated within the first month. Percentages may not sum to 100% because respondents may report multiple concerns.

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Table 3.

Bivariable and Multivariable Logistical Regression Models for Intention to Receive COVID-19 Within 3 Months of Regulatory Approval

	Bivariable (Crude)		Multivariable (Adjusted)
Variable	cOR (95% CI)	P Value	aOR (95% CI)	P Value	Significance^*
Age, decades	1.02 (0.97-1.07)	.548	0.95 (0.90–1.00)	.054
Men^†	2.39 (1.99-2.89)	<.001	2.43 (2.00–2.95)	<.001	***
Influenza vaccine^‡	2.37 (1.79-3.15)	<.001	2.35 (1.75-3.18)	<.001	***
Viral concern^§	2.30 (1.99-2.65)	<.001	2.40 (2.07-2.79)	<.001	***
Patient interaction^‖	0.97 (0.85-1.12)	.704	0.92 (0.79-1.07)	.282
Higher education^¶	1.62 (1.40–1.87)	<.001	1.41 (1.21–1.65)	<.001	***
Poor health^**	0.87 (0.74-1.03)	.115	0.85 (0.71–1.01)	.065
Race^{^††}
White	Reference	–	–	–	–
Black	0.16 (0.10–0.25)	<.001	–	–	–
Asian	1.53 (1.04-2.29)	.036	–	–	–
Other/multiple	0.63 (0.47-0.86)	.003	–	–	–
Hispanic^{^††}	0.97 (0.70–1.36)	.873	–	–	–

cOR, crude odds ratio; CI, confidence interval; aOR, adjusted odds ratio.
↵* Significance with respect to the multivariable model (*P < .05, **P < .01, ***P < .001).
↵† Self-reported sex.
↵‡ Completion of influenza vaccination in the 2019-2020 season.
↵§ “Extremely concerned” or “moderately concerned” about becoming infected with COVID-19 on a 5-point Likert scale.
↵‖ Job responsibility involving direct patient interaction.
↵¶ Master's degree or Doctorate/Professional.
↵** Reporting anything other than “Excellent” or “Very Good” health on a 5-point Likert scale.
↵†† – Not included in the multivariable model.

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Table 4.

Post-Hoc, Exploratory Subgroup Analyses: Intention to Receive COVID-19 Vaccination and Reported Barriers Among White, Black, Hispanic, and Asian Respondents

Variable	N (%)^*
Variable	White	Black	Hispanic	Asian
If a vaccine for novel coronavirus (COVID-19) receives Food and Drug Administration (FDA) approval, when do you intend to become vaccinated?
Within the first month of approval	1152 (38.5)	17 (13.6)	56 (37.1)	61 (40.1)
1 to 3 months after approval	675 (22.6)	14 (11.2)	34 (22.5)	44 (28.9)
4 to 6 months after approval	333 (11.1)	12 (9.6)	19 (12.6)	20 (13.2)
7 to 12 months after approval	197 (6.6)	17 (13.6)	13 (8.6)	9 (5.9)
More than 1 year (12 months) after approval	355 (11.9)	29 (23.2)	18 (11.9)	16 (10.5)
I do not intend to be vaccinated	278 (9.3)	36 (28.8)	11 (7.3)	2 (1.3)
No response	10	1	1	0
Which of the following concerns influence your decision to delay vaccination or to not receive vaccination?^†
The vaccine will not be safe	1015 (55.2)	64 (59.3)	37 (38.9)	56 (61.5)
The vaccine will not be effective	693 (37.7)	38 (35.2)	34 (35.8)	29 (31.9)
I may be allergic to the vaccine	186 (10.1)	23 (21.3)	4 (4.2)	18 (19.8)
Risk of vaccination is more than the benefit	568 (30.9)	40 (37.0)	25 (26.3)	24 (26.4)
Short-term side effects (painful injection, muscle pain, feeling unwell the day of the injection, etc.)	129 (7.0)	18 (16.7)	4 (4.2)	11 (12.1)
Long-term side effects of the vaccine	1052 (57.2)	69 (63.9)	49 (51.6)	43 (47.3)
The vaccine will be too expensive	229 (12.5)	8 (7.4)	15 (15.8)	15 (16.5)
I will not have time to get the vaccine	69 (3.8)	0 (0.0)	9 (9.5)	5 (5.5)
The vaccine will give me novel coronavirus (COVID-19)	81 (4.4)	16(14.8)	5 (5.3)	3 (3.3)
Personal religious, moral or ethical reasons	124 (6.7)	21 (19.4)	3 (3.2)	3 (3.3)
Already been infected with novel coronavirus (COVID-19)	45 (2.4)	2 (1.9)	0 (0.0)	1 (1.1)
Other	266 (14.5)	16 (14.8)	4 (4.2)	11 (12.1)

↵* Percentages refer to all respondents (excluding “no response”) for each item.
↵† Queried of all persons not reporting intention to become vaccinated within the first month. Percentages do not sum to 100% because respondents may report multiple concerns.

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Appendix Table 1.

Estimated Demographics of the Underlying Population Invited to Participate in the Survey

	N (%)^*,^†
	Survey	Health System^‡	University^‡	Composite^§
Age, years
18 to 24	437 (13.1)	1153 (9.9)	1334 (18.7)	2487 (13.3)
25 to 34	974 (29.1)	4054 (34.8)	2763 (38.8)	6817 (36.3)
35 to 44	709 (21.2)	2667 (22.9)	1362 (19.1)	4029 (21.5)
45 to 54	565 (16.9)	1887 (16.2)	812 (11.4)	2699 (14.4)
55 to 64	520 (15.5)	1572 (13.5)	628 (8.8)	2200 (11.7)
65 years or greater	142 (4.2)	315 (2.7)	221 (3.1)	536 (2.9)
Sex
Men	726 (21.8)	2225 (19.1)	2912 (40.9)	5137 (27.4)
Women	2601 (78.0)	9423 (80.9)	4208 (59.1)	13631 (72.6)
Other	7 (0.2)	–	–	–
No response	13	–	–	–
Race^‖
American Indian or Alaska Native	6 (0.2)	57 (0.5)	24 (0.4)	81 (0.4)
Asian/Pacific Islander	129 (3.9)	399 (3.4)	635 (9.6)	1034 (5.7)
Black or African American	104 (3.1)	2007 (17.2)	353 (5.3)	2360 (12.9)
White	2912 (87.6)	8555 (73.4)	5241 (78.9)	13796 (75.4)
Other	79 (2.4)	339 (2.9)	136 (2.0)	475 (2.6)
Multiple	95 (2.9)	291 (2.5)	250 (3.8)	541 (3.0)
No response	22	–	481	481
Hispanic, Latino, or Spanish Origin
Present	152 (4.6)	769 (6.6)	370 (5.2)	1139 (6.1)
Absent	3170 (95.4)	10879 (93.4)	6750 (94.8)	17629 (93.9)
No response	25	–	–	–
Total	3347	11648	7120	18768

↵* The count (N) of individuals in each demographic category are actual counts for the survey and University populations. Health System counts are calculated from the reported percentages and a total of 11,648 employees.
↵† Percentages are calculated from the number of responses for each category (excluding “no response”).
↵‡ Health system demographic statistics are provided by the University of Kansas Health System Human Resources Department, and as current as of 2020. University demographic statistics are provided by the University of Kansas Health Medical Center Office of Enterprise Analytics and are also current as of 2020. Health System and University populations are not completely disjoint (eg, a University faculty physician may also be a member of the Health System medical staff) but this represents a minority of both populations.
↵§ Composite is a combination of Health System and University demographics to approximate the demographic features of the whole underlying eligible population.
↵‖ Race and ethnicity data are reported here as orthogonal demographic features (ie, Hispanic persons may be of any race). Health system and University race and ethnicity data were reported with Hispanic, Latino, or Spanish origin as a racial category rather than two separate features for race and ethnicity. For the health system and University data, Hispanic/Latino persons were assumed to have racial distributions similar to their national distribution for Hispanic persons: 1.4% American Indian or Alaska Native, 0.5% Asian or Pacific Islander, 2.5% Black or African American, 53.0% white, 36.7% other, and 6.0% multiple races (these proportions do not sum to 100% due to rounding).

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Appendix Table 2.

Demographic Features of Records Excluded From Regression Analysis

Demographic	N (%)^*
Age, years
18 to 24	5 (9.1)
25 to 34	17 (30.9)
35 to 44	10 (18.2)
45 to 54	11 (20.0)
55 to 64	9 (16.4)
65 years or greater	3 (5.5)
Sex
Men	2 (4.8)
Women	33 (78.6)
Other	7 (16.7)
No response	13
Race
American Indian or Alaska Native	–
Asian	1 (2.2)
Black or African American	1 (2.2)
White	39 (84.8)
Native Hawaiian or Other Pacific Islander	–
Other	4
Multiple	1
No response	9
Hispanic, Latino, or Spanish Origin
Absent	46 (95.8)
Present	2 (4.2)
No response	7
Educational attainment
Some high school or less	–
High school graduate	2 (4.3)
Some college	3 (6.4)
College graduate	23 (48.9)
Master's degree	12 (25.5)
Doctorate or professional degree	7 (14.9)
No response	8
Clinical role
No clinical responsibilities	11 (20.4)
Attending physician	2 (3.7)
Fellow or resident physician	3 (5.6)
Advanced practice provider (APRN, PA)	1 (1.9)
Licensed nurse (RN, LPN)	15 (27.8)
Clinical pharmacist or pharmacy staff	1 (1.9)
Physical, occupational, or speech therapy	1 (1.9)
Unlicensed care aid	1 (1.9)
Case management or social work	–
Technician (radiology, EKG, lab draw, etc)	3 (5.6)
Clinical laboratory or clinical pathology	2 (3.7)
Administrative or support staff	5 (9.3)
Medical student	2 (3.7)
Nursing student	2 (3.7)
School of health professions student	–
Other student	–
Other	5 (9.3)
No response	1

APRN, advanced practice registered nurse; PA, physician assistant; RN, registered nurse; LPN, licensed practical nurse; EKG, electrocardiogram.
↵* Percentages refer to all respondents (excluding “no response”) for each item.

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Appendix Table 3.
Bivariable Sensitivity Analysis for Alternative Dichotomization Thresholds for Predictor Variables Related to Intention to Receive COVID-19 Within 3 Months of Regulatory Approval
Variable cOR (95% CI) P Value Significance^*
Alternative viral concern^† 3.66 (3.10–4.34) <.001 ***
Alternative higher education^‡ 1.83 (1.50–2.24) <.001 ***
Alternative poor health^§ 0.78 (0.52–1.17) .225
cOR, crude odds ratio; CI, confidence interval; aOR, adjusted odds ratio.
↵* Significance with respect to the bivariable model (*** P < .001).
↵† “Extremely concerned” or “moderately concerned” about becoming infected with COVID-19 on a 5-point Likert scale.
↵‡ College graduate, Master's degree, or Doctorate/Professional degree.
↵§ Reporting anything other than “Excellent”, “Very Good”, or “Good” health on a 5-point Likert scale.

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Appendix Table 4.

Multivariable Sensitivity Analysis Using Alternative Dichotomization Thresholds for Predictor Variables Related to Intention to Receive COVID-19 Within 3 Months of Regulatory Approval

Alternative Dichotomization			Multivariable Odds Ratio (95% CI, P Value)^*
Concern^†	Edu^‡	Health^§	Age	Sex (Men)	Influenza	Direct Interaction
–	–	–	0.95 (0.90–1.00, .054)	2.43 (2.00–2.95, <.001)	2.35 (1.75-3.18, <.001)	0.92 (0.79-1.07, .282)
–	–	Alt	0.94 (0.89-1.00, .036)	2.43 (2.01–2.95, <.001)	2.34 (1.74-3.16, <.001)	0.93 (0.80–1.08, .341)
–	Alt	–	0.97 (0.92–1.02, .284)	2.47 (2.04-3.00, <.001)	2.34 (1.74-3.16, <.001)	0.91 (0.78-1.06, .212)
–	Alt	Alt	0.97 (0.92–1.02, .230)	2.47 (2.04-3.00, <.001)	2.32 (1.72–3.14, <.001)	0.92 (0.79-1.07, .256)
Alt	–	–	0.95 (0.90–1.01, .080)	2.60 (2.13-3.18, <.001)	2.40 (1.77-3.26, <.001)	0.88 (0.75-1.03, .108)
Alt	–	Alt	0.95 (0.90–1.00, .055)	2.60 (2.14-3.18, <.001)	2.38 (1.76-3.24, <.001)	0.89 (0.76-1.04, .137)
Alt	Alt	–	0.98 (0.92–1.03, .366)	2.64 (2.17-3.23, <.001)	2.40 (1.77-3.26, <.001)	0.87 (0.74-1.01, .075)
Alt	Alt	Alt	0.97 (0.92–1.03, .299)	2.65 (2.18-3.23, <.001)	2.38 (1.75-3.23, <.001)	0.88 (0.75-1.02, .096)

Alternative Dichotomization			Multivariable Odds Ratio (95% Cl, P Value)^*
Concern^†	Edu^‡	Health^§	Concern	Education	Health
–	–	–	2.40 (2.07-2.79, <.001)	1.41 (1.21–1.65, <.001)	0.85 (0.71–1.01, .065)
–	–	Alt	2.37 (2.05-2.75, <.001)	1.43 (1.23-1.67, <.001)	0.80 (0.53-1.23, .305)
–	Alt	–	2.40 (2.07-2.79, <.001)	1.54 (1.25-1.91, <.001)	0.84 (0.70–1.01, .057)
–	Alt	Alt	2.38 (2.05-2.76, <.001)	1.58 (1.28-1.95, <.001)	0.78 (0.51–1.19, .237)
Alt	–	–	4.00 (3.35-4.78, <.001)	1.42 (1.21–1.66, <.001)	0.85 (0.71–1.02, .073)
Alt	–	Alt	3.96 (3.32–4.74, <.001)	1.44 (1.23-1.68, <.001)	0.80 (0.52–1.22, .288)
Alt	Alt	–	4.01 (3.36-4.79, <.001)	1.54 (1.24-1.92, <.001)	0.84 (0.70–1.01, .062)
Alt	Alt	Alt	3.97 (3.33-4.75, <.001)	1.58 (1.27-1.95, <.001)	0.77 (0.51–1.18, .222)

CI, confidence interval; Edu, educational attainment; Alt, alternative.
↵* Boldface text indicates P < .05.
↵† Concern about becoming infected with COVID-19. Concern was reported on a 5-point Likert scale (extremely, moderately, somewhat, slightly, not at all). The original (–) threshold divides between moderately/somewhat. The alternative threshold divides between somewhat/slightly.
↵‡ Educational attainment was reported on a 6-point Likert scale (some high school, high school graduate, some college, college graduate, Master's degree and Doctoral/Professional degree). The original (–) threshold divides between College graduate/Master's degree. The alternative threshold divides between some college/college graduate.
↵§ Self-reported health status was reported on a 5-point Likert scale (excellent, very good, good, fair, poor). The original threshold (–) divides between very good/good. The alternative threshold divides between good/fair.

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Appendix Table 5.

Bivariable Sensitivity Analysis Using Alternative Dichotomization Thresholds for Response Variable: Intention to Receive COVID-19 Within 1 Month (Rather Than 3 Months) of Regulatory Approval

Variable	cOR (95% CI)	P Value	Significance^*
Age, decades	1.05 (0.99-1.10)	.079
Men^†	2.23 (1.89-2.64)	<.001	*******
Influenza vaccine^‡	2.44 (1.76-3.46)	<.001	*******
Viral concern^§	1.95 (1.69-2.25)	<.001	*******
Patient interaction^‖	1.17 (1.01–1.34)	.034	*
Higher education^¶	1.54 (1.33-1.77)	<.001	*******
Poor health^**	0.85 (0.71–1.01)	.063
Alternative viral concern^††	2.63 (2.18-3.18)	<.001	*******
Alternative higher education^‡‡	1.82 (1.46-2.28)	<.001	*******
Alternative poor health^§§	0.78 (0.50–1.19)	.259

cOR, crude odds ratio; CI, confidence interval.
↵* Significance (* P < .05, ** P < .01, *** P < .001).
↵† Self-reported gender.
↵‡ Completion of influenza vaccination in the 2019-2020 season.
↵§ “Extremely concerned” or “moderately concerned” about becoming infected with COVID-19 on a 5-point Likert scale.
↵‖ Job responsibility involving direct patient interaction.
↵¶ Master's degree or Doctorate.
↵** Reporting anything other than “Excellent” or “Very Good” health on a 5-point Likert scale.
↵†† “Extremely concerned”, “moderately concerned”, or “somewhat concerned” about becoming infected with COVID-19 on a 5-point Likert scale.
↵‡‡ College graduate, Master's degree, or Doctorate/Professional degree.
↵§§ Reporting anything other than “Excellent”, “Very Good”, or “Good” health on a 5-point Likert scale.

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Appendix Table 6.

Multivariable Sensitivity Analysis Using Alternative Dichotomization Thresholds for Response Variable: Intention to Receive COVID-19 Within 1 Month (Rather Than 3 Months) of Regulatory Approval

Alternative Dichotomization			Multivariable Odds Ratio (95% Cl, P Value)^*
Concern^†	Edu^‡	Health^§	Age	Sex (Men)	Influenza	Direct Interaction
–	–	–	1.00 (0.95-1.06, .918)	2.25 (1.89-2.68, <.001)	2.21 (1.57-3.18, <.001)	1.16 (0.99-1.35, .064)
–	–	Alt	1.00 (0.94-1.05, .938)	2.25 (1.89-2.68, <.001)	2.20 (1.57-3.16, <.001)	1.17 (1.00–1.36, .047)
–	Alt	–	1.02 (0.97-1.08, .427)	2.28 (1.91–2.71, <.001)	2.21 (1.57-3.17, <.001)	1.14 (0.98-1.33, .090)
–	Alt	Alt	1.02 (0.97-1.07, .508)	2.28 (1.92–2.71, <.001)	2.19 (1.56-3.15, <.001)	1.15 (0.99-1.34, .070)
Alt	–	–	1.01 (0.96-1.07, .706)	2.28 (1.92–2.72, <.001)	2.23 (1.58-3.21, <.001)	1.12 (0.96-1.30, .160)
Alt	–	Alt	1.01 (0.95-1.06, .830)	2.29 (1.92–2.73, <.001)	2.22 (1.57-3.19, <.001)	1.13 (0.97-1.31, .128)
Alt	Alt	–	1.03 (0.98-1.09, .269)	2.31 (1.94-2.75, <.001)	2.23 (1.58-3.21, <.001)	1.10 (0.95-1.29, .209)
Alt	Alt	Alt	1.03 (0.97-1.08, .324)	2.32 (1.94-2.76, <.001)	2.22 (1.57-3.19, <.001)	1.11 (0.95-1.30, .174)

Alternative Dichotomization			Multivariable Odds Ratio (95% Cl, P Value)^*
Concern^†	Edu^‡	Health^§	Concern	Education	Health
–	–	–	2.02 (1.74-2.35, <.001)	1.29 (1.11–1.51, .001)	0.84 (0.70–1.01, .066)
–	–	Alt	2.00 (1.72–2.32, <.001)	1.31 (1.13-1.53, <.001)	0.82 (0.52–1.27, .386)
–	Alt	–	2.03 (1.74-2.36, <.001)	1.49 (1.19-1.89, <.001)	0.84 (0.70–1.01, .065)
–	Alt	Alt	2.00 (1.73-2.33, <.001)	1.53 (1.22–1.93, <.001)	0.80 (0.51–1.24, .333)
Alt	–	–	2.74 (2.26-3.34, <.001)	1.30 (1.12–1.52, <.001)	0.86 (0.72–1.03, .101)
Alt	–	Alt	2.72 (2.24-3.31, <.001)	1.32 (1.13-1.54, <.001)	0.84 (0.53-1.29, .429)
Alt	Alt	–	2.75 (2.27-3.35, <.001)	1.51 (1.20–1.91, <.001)	0.86 (0.72–1.03, .100)
Alt	Alt	Alt	2.73 (2.25-3.32, <.001)	1.54 (1.22–1.94, <.001)	0.82 (0.52–1.26, .370)

CI, confidence interval; Edu, educational attainment; Alt, alternative.
↵* Boldface text indicates P < .05.
↵† Concern about becoming infected with COVID-19. Concern was reported on a 5-point Likert scale (extremely, moderately, somewhat, slightly, not at all). The original (–) threshold divides between moderately/somewhat. The alternative threshold divides between somewhat/slightly.
↵‡ Educational attainment was reported on a 6-point Likert scale (some high school, high school graduate, some college, college graduate, Master's degree and Doctoral/Professional degree). The original (–) threshold divides between College graduate/Master's degree. The alternative threshold divides between some college/college graduate.
↵§ Self-reported health status was reported on a 5-point Likert scale (excellent, very good, good, fair, poor). The original threshold (–) divides between very good/good. The alternative threshold divides between good/fair.

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Appendix Table 7.

Bivariable Sensitivity Analysis Using Discretized Age

Response (Intention)^*	Predictor (Age)	cOR (95% CI)	P Value
3 months	Age 30 to 39 years^‡	0.83 (0.69-1.01)	.058
3 months	Age 40 to 54 years^‡	0.84 (0.69-1.01)	.062
3 months	Age >54 years^‡	0.98 (0.80–1.21)	.877
Alt: 1 month	Age 30 to 39 years^‡	0.93 (0.77-1.13)	.483
Alt: 1 month	Age 40 to 54 years^‡	0.94 (0.78-1.14)	.532
Alt: 1 month	Age >54 years^‡	1.12 (0.91–1.37)	.289

cOR, crude odds ratio; CI, confidence interval; Alt, alternative.
↵* Intention to receive COVID-19 within 3 months or 1 month (Alt) of regulatory approval.
↵† Significance (* P < .05, ** P < .01, *** P < .001).
↵‡ Odds ratio relative to the reference class, age < 30 years.

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Appendix Table 8.

Multivariable Sensitivity Analysis Using Discretized Age and Various Alternative Dichotomization Thresholds for Predictor Variables Related to Intention to Receive COVID-19 Within 3 Months of Regulatory Approval

Alternative Dichotomization			Multivariable Odds Ratio (95% Cl, P Value)^*
Concern^†	Edu^‡	Health^§	Age 30 to 39 years^‖	Age 40 to 54 years^‖	Age > 54 years^‖	Sex (Men)	Influenza
–	–	–	0.68 (0.55-0.83, <.001)	0.66 (0.54-0.81, <.001)	0.75 (0.60–0.94, .012)	2.41 (1.99-2.93, <.001)	2.37 (1.76-3.21, <.001)
–	–	Alt	0.67 (0.55-0.83, <.001)	0.65 (0.53-0.80, <.001)	0.74 (0.59-0.93, .008)	2.41 (1.99-2.93, <.001)	2.36 (1.75-3.19, <.001)
–	Alt	–	0.73 (0.60–0.90, .002)	0.73 (0.60–0.90, .003)	0.84 (0.67-1.05, .118)	2.47 (2.04-3.00, <.001)	2.36 (1.75-3.19, <.001)
–	Alt	Alt	0.73 (0.60–0.89, .002)	0.72 (0.59-0.89, .002)	0.83 (0.66-1.03,.097)	2.47 (2.05-3.01, <.001)	2.34 (1.74-3.16, <.001)
Alt	–	–	0.69 (0.56-0.85, <.001)	0.69 (0.56-0.85, <.001)	0.75 (0.60–0.95, .016)	2.59 (2.12–3.16, <.001)	2.42 (1.79-3.30, <.001)
Alt	–	Alt	0.68 (0.56-0.84, <.001)	0.68 (0.55-0.83, <.001)	0.74 (0.59-0.94, .011)	2.59 (2.12–3.17, <.001)	2.41 (1.78-3.27, <.001)
Alt	Alt	–	0.75 (0.61–0.92, .005)	0.76 (0.62–0.94, .009)	0.84 (0.67-1.06, .136)	2.65 (2.18-3.24, <.001)	2.42 (1.79-3.29, <.001)
Alt	Alt	Alt	0.74 (0.60–0.91, .004)	0.75 (0.61–0.92, .006)	0.83 (0.67-1.04, .112)	2.65 (2.18-3.24, <.001)	2.40 (1.77-3.26, <.001)

Alternative Dichotomization			Multivariable Odds Ratio (95% Cl, P Value)^*
Concern^†	Edu^‡	Health^§	Direct Interaction	Concern	Education	Health
–	–	–	0.91 (0.78-1.07, .253)	2.40 (2.07-2.79, <.001)	1.50 (1.28-1.76, <.001)	0.87 (0.73-1.04, .136)
–	–	Alt	0.92 (0.79-1.07, .296)	2.38 (2.05-2.76, <.001)	1.52 (1.30–1.78, <.001)	0.84 (0.55-1.28, .413)
–	Alt	–	0.90 (0.77-1.05, .189)	2.42 (2.08-2.81, <.001)	1.60 (1.29-1.98, <.001)	0.86 (0.72–1.03, .098)
–	Alt	Alt	0.91 (0.78-1.06, .224)	2.40 (2.07-2.78, <.001)	1.63 (1.32–2.02, <.001)	0.80 (0.52–1.22, .296)
Alt	–	–	0.88 (0.75-1.02, .096)	3.99 (3.34-4.77, <.001)	1.51 (1.28-1.77, <.001)	0.87 (0.73-1.05, .140)
Alt	–	Alt	0.88 (0.76-1.03, .117)	3.96 (3.31–4.74, <.001)	1.52 (1.30–1.79, <.001)	0.83 (0.54-1.27, .377)
Alt	Alt	–	0.86 (0.74-1.01, .066)	4.01 (3.36-4.80, <.001)	1.60 (1.29-1.98, <.001)	0.86 (0.72–1.03, .099)
Alt	Alt	Alt	0.87 (0.74-1.02, .082)	3.98 (3.33-4.76, <.001)	1.63 (1.31–2.02, <.001)	0.79 (0.52–1.21,.268)

CI, confidence interval; Edu, educational attainment; Alt, alternative.
↵* Boldface text indicates P < .05.
↵† Concern about becoming infected with COVID-19. Concern was reported on a 5-point Likert scale (extremely, moderately, somewhat, slightly, not at all). The original (–) threshold divides between moderately/somewhat. The alternative threshold divides between somewhat/slightly.
↵‡ Educational attainment was reported on a 6-point Likert scale (some high school, high school graduate, some college, college graduate, Master's degree and Doctoral/Professional degree). The original (–) threshold divides between College graduate/Master's degree. The alternative threshold divides between some college/college graduate.
↵§ Self-reported health status was reported on a 5-point Likert scale (excellent, very good, good, fair, poor). The original threshold (–) divides between very good/good. The alternative threshold divides between good/fair.
↵‖ Odds ratio relative to the reference class, age < 30 years.

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Appendix Table 9.

Alternative Dichotomization			Multivariable Odds Ratio (95% Cl, P Value)^*
Concern^†	Edu^‡	Health^§	Age 30 to 39 years^‖	Age 40 to 54 years^‖	Age > 54 years^‖	Sex (Men)	Influenza
–	–	–	0.81 (0.66-0.99, .043)	0.81 (0.66-1.00, .045)	0.95 (0.76-1.18, .621)	2.24 (1.88-2.67, <.001)	2.22 (1.58-3.19, <.001)
–	–	Alt	0.80 (0.65-0.98, .034)	0.79 (0.65-0.98, .029)	0.93 (0.75-1.16, .524)	2.24 (1.88-2.67, <.001)	2.21 (1.57-3.18, <.001)
–	Alt	–	0.86 (0.70–1.05, .138)	0.88 (0.72–1.07, .201)	1.03 (0.83-1.29, .769)	2.28 (1.92–2.71, <.001)	2.21 (1.57-3.18, <.001)
–	Alt	Alt	0.85 (0.70–1.04, .120)	0.86 (0.71–1.06, .157)	1.02 (0.82–1.27, .848)	2.28 (1.92–2.72, <.001)	2.20 (1.56-3.16, <.001)
Alt	–	–	0.83 (0.68-1.02, .079)	0.84 (0.68-1.04, .108)	0.97 (0.78-1.21, .796)	2.27 (1.91–2.71, <.001)	2.24 (1.59-3.22, <.001)
Alt	–	Alt	0.82 (0.67-1.01, .064)	0.83 (0.67-1.02, .078)	0.96 (0.77-1.19, .698)	2.28 (1.91–2.71, <.001)	2.23 (1.58-3.20, <.001)
Alt	Alt	–	0.88 (0.72–1.08, .234)	0.92 (0.75-1.12, .393)	1.06 (0.86-1.32, .574)	2.31 (1.94-2.76, <.001)	2.24 (1.59-3.22, <.001)
Alt	Alt	Alt	0.88 (0.72–1.07, .209)	0.90 (0.74-1.11, .330)	1.05 (0.85-1.31, .639)	2.32 (1.95-2.76, <.001)	2.23 (1.58-3.20, <.001)

Alternative Dichotomization			Multivariable Odds Ratio (95% Cl, P Value)^*
Concern^†	Edu^‡	Health^§	Direct Interaction	Concern	Education	Health
–	–	–	1.15 (0.99-1.34, .075)	2.03 (1.75-2.36, <.001)	1.36 (1.16-1.59, <.001)	0.86 (0.72–1.03, .113)
–	–	Alt	1.16 (0.99-1.35, .058)	2.01 (1.73-2.33, <.001)	1.38 (1.18-1.61, <.001)	0.85 (0.54-1.31, .470)
–	Alt	–	1.14 (0.98-1.32, .101)	2.04 (1.75-2.37, <.001)	1.53 (1.22-1.94, <.001)	0.86 (0.71–1.03, .095)
–	Alt	Alt	1.15 (0.98-1.33, .081)	2.02 (1.74-2.35, <.001)	1.57 (1.25-1.98, <.001)	0.82 (0.52-1.27, .384)
Alt	–	–	1.11 (0.95-1.29, .185)	2.73 (2.25-3.33, <.001)	1.36 (1.16-1.60, <.001)	0.88 (0.73-1.05, .161)
Alt	–	Alt	1.12 (0.96-1.30, .153)	2.71 (2.24-3.30, <.001)	1.38 (1.18-1.61, <.001)	0.86 (0.55-1.33, .511)
Alt	Alt	–	1.10 (0.94-1.28, .233)	2.75 (2.27-3.35, <.001)	1.54 (1.22-1.95, <.001)	0.87 (0.73-1.04, .138)
Alt	Alt	Alt	1.11 (0.95-1.29, .198)	2.73 (2.25-3.33, <.001)	1.57 (1.25-1.99, <.001)	0.83 (0.53-1.28, .419)

CI, confidence interval; Edu, educational attainment; Alt, alternative.
↵* Boldface text indicates P < .05.
↵† Concern about becoming infected with COVID-19. Concern was reported on a 5-point Likert scale (extremely, moderately, somewhat, slightly, not at all). The original (–) threshold divides between moderately/somewhat. The alternative threshold divides between somewhat/slightly.
↵‡ Educational attainment was reported on a 6-point Likert scale (some high school, high school graduate, some college, college graduate, Master's degree and Doctoral/Professional degree). The original (–) threshold divides between College graduate/Master's degree. The alternative threshold divides between some college/college graduate.
↵§ Self-reported health status was reported on a 5-point Likert scale (excellent, very good, good, fair, poor). The original threshold (–) divides between very good/good. The alternative threshold divides between good/fair.
↵‖ Odds ratio relative to the reference class, age < 30 years.

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Appendix Table 10.

Multivariable Sensitivity Analysis for Inclusion of Survey Completion Timestamp on 3-Month Vaccination Intention

Alternative Dichotomization			Multivariable Odds Ratio (95% Cl, P Value)^*
Concern^†	Edu^‡	Health^§	Age	Sex (Men)	Influenza	Direct Interaction	Concern
–	–	–	0.95 (0.90–1.00, .049)	2.43 (2.01– 2.95, <.001)	2.34 (1.74-3.17, <.001)	0.92 (0.79-1.07, .298)	2.40 (2.07-2.79, <.001)
–	–	Alt	0.94 (0.89-1.00, .033)	2.43 (2.01– 2.96, <.001)	2.33 (1.73-3.15, <.001)	0.93 (0.80–1.08, .359)	2.37 (2.05-2.75, <.001)
–	Alt	–	0.97 (0.92-1.02, .261)	2.47 (2.04-3.00, <.001)	2.32 (1.73-3.14, <.001)	0.91 (0.78-1.06, .224)	2.41 (2.07-2.79, <.001)
–	Alt	Alt	0.97 (0.92-1.02, .210)	2.47 (2.05-3.00, <.001)	2.31 (1.71–3.12, <.001)	0.92 (0.79-1.07, .270)	2.38 (2.05-2.76, <.001)
Alt	–	–	0.95 (0.90–1.00, .073)	2.60 (2.14-3.19, <.001)	2.38 (1.76-3.24, <.001)	0.88 (0.76-1.03, .117)	4.01 (3.36-4.80, <.001)
Alt	–	Alt	0.95 (0.90–1.00, .050)	2.61 (2.14-3.19, <.001)	2.36 (1.75-3.21, <.001)	0.89 (0.76-1.04, .147)	3.97 (3.33-4.75, <.001)
Alt	Alt	–	0.97 (0.92-1.03, .336)	2.65 (2.18-3.24, <.001)	2.38 (1.76-3.24, <.001)	0.87 (0.74-1.02, .081)	4.02 (3.36-4.81, <.001)
Alt	Alt	Alt	0.97 (0.92-1.02, .273)	2.65 (2.18-3.24, <.001)	2.36 (1.74-3.21, <.001)	0.88 (0.75-1.03, .103)	3.98 (3.34-4.76, <.001)

Alternative Dichotomization			Multivariable Odds Ratio (95% Cl, P Value)^*
Concern^†	Edu^‡	Health^§	Education	Health	Timestamp^‖
–	–	–	1.41 (1.20–1.64, <.001)	0.85 (0.71–1.01, .066)	0.99 (0.96-1.01, .241)
–	–	Alt	1.43 (1.22-1.66, <.001)	0.80 (0.53-1.23, .306)	0.99 (0.96-1.01, .240)
–	Alt	–	1.55 (1.25-1.91, <.001)	0.84 (0.70–1.01, .059)	0.98 (0.96-1.01, .167)
–	Alt	Alt	1.58 (1.28-1.96, <.001)	0.78 (0.51–1.19, .239)	0.98 (0.96-1.01, .162)
Alt	–	–	1.41 (1.21–1.65, <.001)	0.85 (0.71–1.02, .073)	0.98 (0.96-1.01, .164)
Alt	–	Alt	1.43 (1.22-1.67, <.001)	0.80 (0.52-1.22, .288)	0.98 (0.96-1.01, .163)
Alt	Alt	–	1.55 (1.25-1.92, <.001)	0.84 (0.70–1.01, .063)	0.98 (0.96-1.01, .115)
Alt	Alt	Alt	1.58 (1.28-1.96, <.001)	0.77 (0.51–1.18, .224)	0.98 (0.96-1.00, .112)

CI, confidence interval; Edu, educational attainment; Alt, alternative.
↵* Boldface text indicates P < .05.
↵† Concern about becoming infected with COVID-19. Concern was reported on a 5-point Likert scale (extremely, moderately, somewhat, slightly, not at all). The original (–) threshold divides between moderately/somewhat. The alternative threshold divides between somewhat/slightly.
↵‡ Educational attainment was reported on a 6-point Likert scale (some high school, high school graduate, some college, college graduate, Master's degree and Doctoral/Professional degree). The original (–) threshold divides between College graduate/Master's degree. The alternative threshold divides between some college/college graduate.
↵§ Self-reported health status was reported on a 5-point Likert scale (excellent, very good, good, fair, poor). The original threshold (–) divides between very good/good. The alternative threshold divides between good/fair.
↵‖ Measured in days.

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Appendix Table 11.

Multivariable Sensitivity Analysis for Inclusion of Survey Completion Timestamp on 1-Month Vaccination Intention

Alternative Dichotomization			Multivariable Odds Ratio (95% Confidence Interval, P Value)^*
Concern^†	Edu^‡	Health^§	Age	Sex (Men)	Influenza	Direct Interaction	Concern
–	–	–	1.00 (0.95-1.06, .953)	2.25 (1.89-2.68, <.001)	2.20 (1.56-3.16, <.001)	1.16 (0.99-1.35, .060)	2.02 (1.74-2.35, <.001)
–	–	Alt	1.00 (0.94-1.05, .903)	2.26 (1.90–2.69, <.001)	2.19 (1.56-3.15, <.001)	1.17 (1.00 to 1.36, .045)	2.00 (1.72-2.32, <.001)
–	Alt	–	1.02 (0.97-1.08, .462)	2.28 (1.91–2.71, <.001)	2.20 (1.56-3.15, <.001)	1.14 (0.98-1.33, .085)	2.03 (1.74-2.36, <.001)
–	Alt	Alt	1.02 (0.96-1.07, .546)	2.28 (1.92-2.71, <.001)	2.18 (1.55-3.13, <.001)	1.15 (0.99-1.34, .066)	2.00 (1.73-2.33, <.001)
Alt	–	–	1.01 (0.96-1.07, .740)	2.29 (1.92-2.73, <.001)	2.22 (1.57-3.18, <.001)	1.12 (0.96-1.30, .152)	2.75 (2.26-3.35, <.001)
Alt	–	Alt	1.00 (0.95-1.06, .865)	2.29 (1.92-2.73, <.001)	2.20 (1.56-3.17, <.001)	1.13 (0.97-1.31, .121)	2.72 (2.25-3.32, <.001)
Alt	Alt	–	1.03 (0.98-1.09, .295)	2.31 (1.94-2.75, <.001)	2.22 (1.57-3.19, <.001)	1.11 (0.95-1.29, .199)	2.75 (2.27-3.35, <.001)
Alt	Alt	Alt	1.03 (0.97-1.08, .353)	2.32 (1.95-2.76, <.001)	2.20 (1.56-3.17, <.001)	1.11 (0.96-1.30, .165)	2.73 (2.25-3.33, <.001)

Alternative Dichotomization			Multivariable Odds Ratio (95% Confidence Interval, P Value)^*
Concern^†	Edu^‡	Health^§	Education	Health	Timestamp^‖
–	–	–	1.29 (1.11–1.50, .001)	0.84 (0.70–1.01, .067)	0.99 (0.96-1.01, .246)
–	–	Alt	1.31 (1.13-1.53, <.001)	0.82 (0.52-1.27, .388)	0.99 (0.96-1.01, .244)
–	Alt	–	1.50 (1.19-1.90, <.001)	0.84 (0.70–1.01, .067)	0.98 (0.96-1.01, .184)
–	Alt	Alt	1.54 (1.22-1.94, <.001)	0.81 (0.51–1.24, .337)	0.98 (0.96-1.01, .180)
Alt	–	–	1.30 (1.11–1.52, <.001)	0.86 (0.72-1.03, .102)	0.98 (0.96-1.01, .198)
Alt	–	Alt	1.32 (1.13-1.54, <.001)	0.84 (0.53-1.29, .431)	0.98 (0.96-1.01, .197)
Alt	Alt	–	1.51 (1.20–1.91, <.001)	0.86 (0.72-1.03, .103)	0.98 (0.96-1.01, .149)
Alt	Alt	Alt	1.55 (1.23-1.95, <.001)	0.82 (0.52-1.26, .373)	0.98 (0.96-1.01, .146)

CI, confidence interval; Edu, educational attainment; Alt, alternative.
↵* Boldface text indicates P < .05.
↵† Concern about becoming infected with COVID-19. Concern was reported on a 5-point Likert scale (extremely, moderately, somewhat, slightly, not at all). The original (–) threshold divides between moderately/somewhat. The alternative threshold divides between somewhat/slightly.
↵‡ Educational attainment was reported on a 6-point Likert scale (some high school, high school graduate, some college, college graduate, Master's degree and Doctoral/Professional degree). The original (–) threshold divides between College graduate/Master's degree. The alternative threshold divides between some college/college graduate.
↵§ Self-reported health status was reported on a 5-point Likert scale (excellent, very good, good, fair, poor). The original threshold (–) divides between very good/good. The alternative threshold divides between good/fair.
↵‖ Measured in days.

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Appendix Table 12.

Bivariable Sensitivity Analysis Including Race

Response (Intention)^*	Predictor (Race)	cOR (95% CI)	P Value	Significance^†
3 months	Black or African American^‡	0.16 (0.10–0.25)	<.001	*******
3 months	Asian^‡	1.53 (1.04-2.29)	.036	*
3 months	Other/Multiple race^‡	0.65 (0.48-0.88)	.006	**
Alt: 1 month	Black or African American^‡	0.21 (0.11–0.37)	<.001	*******
Alt: 1 month	Asian^‡	1.08 (0.75-1.56)	.677
Alt: 1 month	Other/Multiple race^‡	0.87 (0.63-1.20)	.401

cOR, crude odds ratio; CI, confidence interval; Alt, alternative.
↵* Intention to receive COVID-19 within 3 months or 1 month (Alt) of regulatory approval.
↵† Significance (* P < .05, ** P < .01, *** P < .001).
↵‡ Odds ratio relative to the reference class, White race.

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Appendix Table 13.

Multivariable Sensitivity Analysis for Inclusion of Four-Level Race (White, Black, Asian, Other/Multiple Race) on 3-Month Vaccination Intention

Alternative Dichotomization			Multivariable Odds Ratio (95% Confidence Interval, P Value)^*
Concern^†	Edu^‡	Health^§	Age	Sex (Men)	Influenza	Direct Interaction	Concern
–	–	–	0.94 (0.89-1.00, .037)	2.48 (2.04-3.03, <.001)	2.22 (1.64-3.02, <.001)	0.91 (0.78-1.06, .227)	2.53 (2.17-2.95, <.001)
–	–	Alt	0.94 (0.89-0.99, .025)	2.48 (2.04-3.03, <.001)	2.21 (1.63-3.01, <.001)	0.92 (0.79-1.07, .273)	2.50 (2.15-2.92, <.001)
–	Alt	–	0.96 (0.91–1.02, .190)	2.53 (2.09-3.09, <.001)	2.21 (1.63-3.01, <.001)	0.90 (0.77-1.05, .187)	2.54 (2.18-2.96, <.001)
–	Alt	Alt	0.96 (0.91–1.02, .153)	2.53 (2.09-3.09, <.001)	2.20 (1.62-2.99, <.001)	0.91 (0.78-1.06, .225)	2.51 (2.16-2.93, <.001)
Alt	–	–	0.95 (0.89-1.00, .060)	2.65 (2.17-3.26, <.001)	2.23 (1.64-3.05, <.001)	0.87 (0.74-1.02, .088)	4.15 (3.47-4.99, <.001)
Alt	–	Alt	0.94 (0.89-1.00, .042)	2.65 (2.17-3.26, <.001)	2.21 (1.62-3.03, <.001)	0.88 (0.75-1.03, .110)	4.12 (3.44-4.94, <.001)
Alt	Alt	–	0.97 (0.92-1.02, .270)	2.71 (2.22-3.32, <.001)	2.23 (1.64-3.06, <.001)	0.86 (0.74-1.01, .071)	4.16 (3.47-4.99, <.001)
Alt	Alt	Alt	0.97 (0.91–1.02, .222)	2.71 (2.22-3.32, <.001)	2.21 (1.62-3.03, <.001)	0.87 (0.74-1.02, .089)	4.12 (3.45-4.95, <.001)

Alternative Dichotomization			Multivariable Odds Ratio (95% Confidence Interval, P Value)^*
Concern^†	Edu^‡	Health^§	Education	Health	Black^‖	Asian^‖	Other/Multiple Race^‖
–	–	–	1.36 (1.16-1.60, <.001)	0.86 (0.71–1.03, .098)	0.13 (0.08-0.21, <.001)	1.15 (0.77-1.76, .509)	0.59 (0.43-0.82, .001)
–	–	Alt	1.38 (1.18-1.62, <.001)	0.82 (0.54-1.26, .366)	0.13 (0.08-0.22, <.001)	1.16 (0.77-1.78, .481)	0.59 (0.42-0.81, .001)
–	Alt	–	1.44 (1.16-1.78, .001)	0.85 (0.71–1.02, .082)	0.14 (0.08-0.22, <.001)	1.20 (0.80–1.83, .394)	0.59 (0.43-0.82, .002)
–	Alt	Alt	1.47 (1.18-1.82, <.001)	0.80 (0.52-1.23, .299)	0.14 (0.08-0.22, <.001)	1.21 (0.81–1.85, .365)	0.59 (0.43-0.82, .002)
Alt	–	–	1.38 (1.17-1.62, <.001)	0.86 (0.72-1.04, .117)	0.14 (0.08-0.23, <.001)	1.12 (0.74-1.73, .590)	0.59 (0.42-0.82, .002)
Alt	–	Alt	1.39 (1.19-1.64, <.001)	0.82 (0.53-1.26, .353)	0.14 (0.08-0.23, <.001)	1.13 (0.75-1.74, .560)	0.58 (0.42-0.81, .001)
Alt	Alt	–	1.44 (1.15-1.79, .001)	0.85 (0.71–1.03, .094)	0.14 (0.09-0.24, <.001)	1.17 (0.77-1.79, .470)	0.59 (0.43-0.82, .002)
Alt	Alt	Alt	1.46 (1.18-1.82, <.001)	0.79 (0.52-1.22, .284)	0.14 (0.09-0.24, <.001)	1.18 (0.78-1.81, .437)	0.59 (0.42-0.82, .002)

CI, confidence interval; Edu, educational attainment; Alt, alternative.
↵* Boldface text indicates P < .05.
↵† Concern about becoming infected with COVID-19. Concern was reported on a 5-point Likert scale (extremely, moderately, somewhat, slightly, not at all). The original (–) threshold divides between moderately/somewhat. The alternative threshold divides between somewhat/slightly.
↵‡ Educational attainment was reported on a 6-point Likert scale (some high school, high school graduate, some college, college graduate, Master's degree and Doctoral/Professional degree). The original (–) threshold divides between College graduate/Master's degree. The alternative threshold divides between some college/college graduate.
↵§ Self-reported health status was reported on a 5-point Likert scale (excellent, very good, good, fair, poor). The original threshold (–) divides between very good/good. The alternative threshold divides between good/fair.
↵‖ Odds ratio relative to the reference class, White race.

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Appendix Table 14.

Multivariable Sensitivity Analysis for Inclusion of Four-Level Race (White, Black, Asian, Other/Multiple) on 1-Month Vaccination Intention

Alternative Dichotomization			Multivariable Odds Ratio (95% Confidence Interval, P Value)^*
Concern^†	Edu^‡	Health^§	Age	Sex (Men)	Influenza	Direct Interaction	Concern
–	–	–	1.00 (0.95-1.06, .980)	2.27 (1.91–2.71, <.001)	2.12 (1.50–3.05, <.001)	1.14 (0.98-1.33, .094)	2.07 (1.77-2.41, <.001)
–	–	Alt	1.00 (0.94-1.05, .893)	2.28 (1.91–2.72, <.001)	2.11 (1.49-3.04, <.001)	1.15 (0.99-1.34, .073)	2.04 (1.76-2.38, <.001)
–	Alt	–	1.02 (0.97-1.08, .482)	2.30 (1.93-2.74, <.001)	2.12 (1.50–3.05, <.001)	1.13 (0.97-1.32, .119)	2.07 (1.78-2.41, <.001)
–	Alt	Alt	1.02 (0.96-1.07, .559)	2.31 (1.94-2.75, <.001)	2.11 (1.49-3.03, <.001)	1.14 (0.98-1.33, .095)	2.05 (1.76-2.38, <.001)
Alt	–	–	1.01 (0.95-1.07, .745)	2.30 (1.93-2.74, <.001)	2.11 (1.50–3.05, <.001)	1.10 (0.95-1.29, .210)	2.74 (2.26-3.35, <.001)
Alt	–	Alt	1.01 (0.95-1.06, .853)	2.30 (1.93-2.75, <.001)	2.11 (1.49-3.03, <.001)	1.11 (0.95-1.30, .174)	2.72 (2.24-3.32, <.001)
Alt	Alt	–	1.03 (0.98-1.09, .292)	2.33 (1.95-2.78, <.001)	2.12 (1.50–3.06, <.001)	1.09 (0.94-1.28, .251)	2.74 (2.26-3.35, <.001)
Alt	Alt	Alt	1.03 (0.97-1.08, .342)	2.33 (1.96-2.78, <.001)	2.11 (1.49-3.05, <.001)	1.10 (0.95-1.29, .212)	2.72 (2.24-3.32, <.001)

Alternative Dichotomization			Multivariable Odds Ratio (95% Confidence Interval, P Value)^*
Concern^†	Edu^‡	Health^§	Education	Health	Black^‖	Asian^‖	Other/Multiple Race^‖
–	–	–	1.28 (1.09-1.49, .002)	0.85 (0.71–1.02, .091)	0.20 (0.10–0.35, <.001)	0.87 (0.59-1.28, .485)	0.84 (0.60–1.17, .299)
–	–	Alt	1.30 (1.11–1.51, <.001)	0.84 (0.53-1.29, .428)	0.20 (0.10–0.35, <.001)	0.88 (0.60–1.29, .525)	0.83 (0.59-1.16, .279)
–	Alt	–	1.44 (1.14-1.83, .002)	0.85 (0.71–1.02, .087)	0.20 (0.10–0.36, <.001)	0.90 (0.61–1.31, .574)	0.84 (0.60–1.17, .312)
–	Alt	Alt	1.47 (1.17-1.87, .001)	0.82 (0.52-1.27, .382)	0.20 (0.10–0.37, <.001)	0.91 (0.62-1.33, .624)	0.83 (0.59-1.16, .291)
Alt	–	–	1.29 (1.11–1.51, .001)	0.87 (0.73-1.05, .143)	0.21 (0.11–0.38, <.001)	0.87 (0.59-1.28, .490)	0.85 (0.60–1.18, .330)
Alt	–	Alt	1.31 (1.12-1.53, <.001)	0.85 (0.54-1.31, .474)	0.21 (0.11–0.37, <.001)	0.88 (0.60–1.29, .522)	0.84 (0.60–1.17, .308)
Alt	Alt	–	1.45 (1.15-1.85, .002)	0.87 (0.72-1.04, .136)	0.22 (0.11-0.39, <.001)	0.90 (0.61-1.32, .591)	0.85 (0.60–1.18, .343)
Alt	Alt	Alt	1.48 (1.18-1.88, .001)	0.83 (0.53-1.29, .421)	0.22 (0.11-0.39, <.001)	0.91 (0.62-1.33, .631)	0.84 (0.60–1.18, .319)

CI, confidence interval; Edu, educational attainment; Alt, alternative.
↵* Boldface text indicates P < .05.
↵* ^†Concern about becoming infected with COVID-19. Concern was reported on a 5-point Likert scale (extremely, moderately, somewhat, slightly, not at all). The original (–) threshold divides between moderately/somewhat. The alternative threshold divides between somewhat/slightly.
↵* ^‡Educational attainment was reported on a 6-point Likert scale (some high school, high school graduate, some college, college graduate, Master's degree and Doctoral/Professional degree). The original (–) threshold divides between College graduate/Master's degree. The alternative threshold divides between some college/college graduate.
↵* ^§Self-reported health status was reported on a 5-point Likert scale (excellent, very good, good, fair, poor). The original threshold (–) divides between very good/good. The alternative threshold divides between good/fair.
↵* ^‖Odds ratio relative to the reference class, White race.