Post-vaccination adverse reactions, decision regret, and willingness to pay for the booster dose of COVID-19 vaccine among healthcare workers: A mediation analysis

Figures & data

Figure 1. The directed acyclic graph describes the relation among post-vaccination adverse reactions, decision regret, and WTP for the booster dose of COVID-19 vaccine.

Figure 2. Process of collecting the willingness to pay and different payment values for the respondents.

Table 1. Univariate analysis of factors associated with WTP for the booster dose of COVID-19 vaccine.

Variables	Category	n	%	${\chi }^2$	P-value
Total		1054	47.1
Post-vaccination adverse reaction				12.484	<0.001
	No	931	49.1
	Yes	123	31.7
Age(years)				2.261	0.520
	<30	363	47.1
	30   39	466	45.1
	40   49	183	50.8
	≥50	42	52.4
Sex				2.969	0.085
	Male	165	40.6
	Female	889	48.3
Education				3.617	0.306
	Senior Secondary and below	71	39.4
	Junior college	162	52.5
	Undergraduate	709	46.7
	Graduate	112	46.4
Occupation				2.409	0.492
	Doctor	174	44.3
	Nurse	670	48.8
	Medical Technician	127	44.9
	Others	83	42.2
Professional titles				7.613	0.055
	Primary grade and below	562	45.2
	Medium grade	359	46.2
	Associate professor	86	53.5
	Professor	47	63.8
Underlying disease				2.670	0.102
	Yes	121	39.7
	No	933	48.0

Table 2. Descriptive statistics and correlations among study variables (n = 1,054).

Variables	Descriptive	1	2	3
1. Post-vaccination adverse reaction (Yes)	123 (11.7%)	1.00
2. Decision regret	8.6 (±3.5)	0.14***	1.00
3. WTP for the booster dose (Yes)	917 (87.0%)	−0.11***	−0.21***	1.00

***, p  < 0.001. For the category variable, we used count (percentage) for the description; while for the continuous variable, we used mean (±sd).

Table 3. Testing of the mediating role of decision regret.

Variable	Model 1		Model 2		Model 3
	OR	95%CI	B	95%CI	OR	95%CI
Independent variable
Post-vaccination adverse reaction (No)
Yes	0.48***	0.32   0.72	1.65***	1.01   2.30	0.58**	0.38   0.87
Mediator
Decision regret					0.89***	0.85   0.92
Controlled variable
Age (<30)
30   39	1.07	0.79   1.45	−0.27	−0.79   0.24	1.04	0.76   1.41
40   49	1.55*	1.03   2.32	−0.47	−1.15   0.20	1.48	0.98   2.24
≥50	1.70	0.85   3.41	−0.05	−1.19   1.10	1.72	0.86   3.50
Sex (Male)
Female	1.61*	1.09   2.40	0.08	−0.57   0.73	1.66	1.12   2.50
Education (Senior Secondary and below)
Junior college	2.25*	1.21   4.26	−1.92***	−2.96 -0.87	1.83	0.96   3.49
Undergraduate	1.79*	1.05   3.07	−2.02***	−2.91 -1.14	1.41	0.82   2.46
Graduate	2.24*	1.14   4.44	−2.15***	−3.28 -1.03	1.76	0.89   3.54
Underlying disease (No)
Yes	0.70	0.46   1.04	−0.06	−0.73   0.61	0.69	0.45   1.03

***, P-value <.001; **, P-value <.01; *, P-value <.05. The outcome of Model 1 and 3 was WTP for the booster dose of COVID-19 vaccine (1 denotes “Yes”); the outcome of Model 2 was decision regret.

Abbreviation: OR, odds ratio; CI, confidence interval; B, standardized beta regression coefficient.

Table 4. Path analysis coefficients for direct and indirect associations.

	Outcome1		Outcome2
	Coefficient	P-value	Coefficient	P-value
Decision regret	−0.10	<0.001	−0.17	<0.001
Post-vaccination adverse reaction (Yes vs. No)
Direct effect	−0.57	0.018	−0.51	0.112
Indirect effect	1.74	<0.001	1.57	<0.001

Outcome1 denote willing-to-pay below the price of CNY 100 vs. not willing-to-pay, and outcome2 denote willing-to-pay above the price of CNY 100 vs. not willing-to-pay. Other factors (age, sex, education, underlying disease) were included in the model.