Trends in COVID-19 vaccination intent from pre- to post-COVID-19 vaccine distribution and their associations with the 5C psychological antecedents of vaccination by sex and age in Japan

Figures & data

Table 1. Participants’ characteristics

	Men						Women
	20–39 years		40–59 years		60–79 years		20–39 years		40–59 years		60–79 years
	N= 353		N= 527		N= 435		N= 367		N= 495		N= 478
	n (%)		n (%)		n (%)		n (%)		n (%)		n (%)
Marital status
Married	90	(25.5)	296	(56.2)	348	(80.0)	127	(34.6)	337	(68.1)	360	(75.3)
Not married	263	(74.5)	231	(43.8)	87	(20.0)	240	(65.4)	158	(31.9)	118	(24.7)
Employment status
Working	279	(79.0)	475	(90.1)	222	(51.0)	253	(68.9)	287	(58.0)	103	(21.5)
Not working	74	(21.0)	52	(9.9)	213	(49.0)	114	(31.1)	208	(42.0)	375	(78.5)
Residential area
Tokyo metropolitan area^a	103	(29.2)	175	(33.2)	134	(30.8)	118	(32.2)	151	(30.5)	155	(32.4)
Other	250	(70.8)	352	(66.8)	301	(69.2)	249	(67.8)	344	(69.5)	323	(67.6)
Living arrangement
Alone	99	(28.0)	109	(20.7)	61	(14.0)	65	(17.7)	56	(11.3)	83	(17.4)
With others	254	(72.0)	418	(79.3)	374	(86.0)	302	(82.3)	439	(89.7)	395	(82.6)
Educational attainment
University graduate or above	248	(70.3)	329	(62.4)	284	(65.3)	228	(62.1)	181	(36.6)	118	(24.7)
Below university graduate level	105	(29.7)	198	(37.6)	151	(34.7)	139	(37.9)	314	(63.4)	360	(75.3)
Annual personal income
<2 million yen [approximately 19,000 USD]	123	(34.8)	87	(16.5)	93	(21.4)	210	(57.2)	366	(73.9)	385	(80.5)
2-<4 million yen [19,000 -< 38,000]	96	(27.2)	114	(21.6)	202	(46.4)	114	(31.1)	87	(17.6)	70	(14.6)
4-<6 million yen [38,000 -< 57,000]	92	(26.1)	136	(25.8)	89	(20.5)	28	(7.6)	34	(6.9)	14	(2.9)
≥6 million yen or more [57,000-]	42	(11.9)	190	(36.1)	51	(11.7)	15	(4.1)	8	(1.6)	9	(1.9)
Underlying diseases^b
Yes	49	(13.9)	143	(27.1)	249	(57.2)	27	(7.4)	92	(18.6)	194	(40.6)
No	304	(86.1)	384	(72.9)	186	(42.8)	340	(92.6)	403	(81.4)	284	(59.4)

^aTokyo metropolitan area included Tokyo, Kanagawa, Saitama, and Chiba prefectures.

^bUnderlying diseases included heart disease, respiratory disease, kidney disease, diabetes, and hypertension.

Figure 1. The proportion of participants who had COVID-19 vaccination intent during the baseline (January 2021) and second wave (April 2021) surveys. The McNemar test was performed to compare the prevalence (* p value < .05, ** p value < .001).

Table 2. Mean value of 5C psychological antecedents for age, sex, and vaccination intent

	Total	Participants having COVID-19 vaccination intent ^a	Participants not having COVID-19 vaccination intent		Total	Participants having COVID-19 vaccination intent	Participants not having COVID-19 vaccination intent		Total	Participants having COVID-19 vaccination intent	Participants not having COVID-19 vaccination intent
	Men
	20–39 years				40–59 years				60–79 years
n	353	222	131		527	358	169		435	399	36
(%)		(62.9)	(37.1)			(67.9)	(32.1)			(91.7)	(9.3)
	Mean	Mean	Mean		Mean	Mean	Mean		Mean	Mean	Mean
	(SD)	(SD)	(SD)	p-value ^c	(SD)	(SD)	(SD)	p-value	(SD)	(SD)	(SD)	p-value
Confidence ^b	4.42	4.81	3.77	<0.001	4.32	4.73	3.46	<0.001	4.95	5.05	3.85	<0.001
	(1.06)	(0.90)	(0.99)		(1.15)	(0.95)	(1.05)		(0.95)	(0.88)	(0.98)
Complacency ^b	3.31	2.99	3.85	<0.001	2.90	2.57	3.60	<0.001	2.56	2.44	3.90	<0.001
	(1.34)	(1.39)	(1.08)		(1.25)	(1.16)	(1.16)		(1.19)	(1.11)	(1.19)
Constraints ^b	3.64	3.32	4.19	<0.001	3.28	3.00	3.87	<0.001	2.51	2.38	3.99	<0.001
	(1.26)	(1.31)	(0.94)		(1.15)	(1.16)	(0.86)		(1.17)	(1.10)	(0.91)
Calculation ^b	4.70	4.73	4.66	0.478	4.75	4.77	4.71	0.574	4.83	4.78	5.37	0.002
	(0.94)	(0.91)	(0.97)		(1.07)	(1.07)	(1.07)		(1.09)	(1.08)	(1.02)
Collective responsibility ^b	4.73	5.14	4.03	<0.001	4.99	5.47	3.99	<0.001	5.57	5.73	3.89	<0.001
	(1.08)	(1.06)	(0.68)		(1.19)	(1.02)	(0.86)		(1.07)	(0.93)	(1.05)
	Women
	20–39 years				40–59 years				60–79 years
n	367	212	155		495	323	172		478	408	70
(%)		(57.8)	(42.2)			(65.3)	(34.7)			(85.4)	(14.6)
	Mean	Mean	Mean		Mean	Mean	Mean		Mean	Mean	Mean
	(SD)	(SD)	(SD)	p-value ^c	(SD)	(SD)	(SD)	p-value	(SD)	(SD)	(SD)	p-value
Confidence	4.20	4.68	3.55	<0.001	4.34	4.70	3.66	<0.001	4.87	5.06	3.70	<0.001
	(1.04)	(0.84)	(0.93)		(1.01)	(0.79)	(1.01)		(0.94)	(0.79)	(0.92)
Complacency	3.16	2.95	3.44	<0.001	2.98	2.64	3.61	<0.001	2.62	2.43	3.70	<0.001
	(1.13)	(1.21)	(0.94)		(1.17)	(1.12)	(1.00)		(1.13)	(1.03)	(1.08)
Constraints	3.52	3.28	3.84	<0.001	3.27	2.96	3.85	<0.001	2.63	2.43	3.80	<0.001
	(1.09)	(1.15)	(0.90)		(1.18)	(1.21)	(0.87)		(1.13)	(1.05)	(0.84)
Calculation	4.84	4.88	4.78	0.368	5.01	4.89	5.23	<0.001	5.07	5.05	5.18	0.310
	(1.05)	(1.01)	(1.10)		(0.95)	(0.85)	(1.08)		(0.99)	(0.97)	(1.11)
Collective responsibility	4.77	5.27	4.09	<0.001	5.00	5.51	4.05	<0.001	5.54	5.80	4.01	<0.001
	(1.06)	(0.97)	(0.77)		(1.14)	(0.92)	(0.87)		(1.07)	(0.87)	(0.77)

SD: standard deviation

^aWe defined “a participant having COVID-19 vaccination intent” as meeting one of the following two criteria; 1) pertaining to the question on how likely they were to get vaccinated for COVID-19, the participant responded “very likely” or “somewhat likely, 2) pertaining to the question on whether they planned to be vaccinated or not, the participant responded “yes” or “already vaccinated”.

^bAverage of the three subscales.

^cp-value was calculated using t test.

Table 3. Individual psychological factors associated with COVID-19 vaccination intent

	Odds ratio^a	95% confidence interval	p-value	Odds ratio	95% confidence interval	p-value	Odds ratio	95% confidence interval	p-value
	Men
	20–39 years			40–59 years			60–79 years
Confidence	3.90	(2.45-6.22)	<0.001	3.16	(2.16-4.61)	<0.001	2.47	(1.21-5.06)	0.014
Complacency	0.79	(0.55-1.12)	0.187	0.83	(0.59-1.16)	0.266	1.18	(0.63-2.22)	0.600
Constraints	0.66	(0.44-0.99)	0.043	0.69	(0.47-1.00)	0.048	0.38	(0.21-0.71)	0.002
Calculation	0.55	(0.36-0.84)	0.006	0.50	(0.35-0.70)	<0.001	0.24	(0.12-0.47)	<0.001
Collective responsibility	3.48	(2.02-5.97)	<0.001	4.92	(2.90-8.36)	<0.001	7.49	(2.81-20.00)	<0.001
	Women
	20–39 years			40–59 years			60–79 years
Confidence	4.53	(2.69-7.64)	<0.001	3.32	(2.15-5.12)	<0.001	4.80	(2.39-9.63)	<0.001
Complacency	1.17	(0.78-1.74)	0.451	0.81	(0.56-1.16)	0.249	0.71	(0.40-1.25)	0.236
Constraints	0.69	(0.44-1.08)	0.100	1.10	(0.76-1.59)	0.601	0.91	(0.49-1.70)	0.771
Calculation	0.41	(0.27-0.61)	<0.001	0.31	(0.20-0.46)	<0.001	0.52	(0.33-0.83)	0.006
Collective responsibility	5.48	(2.93-10.23)	<0.001	8.82	(5.01-15.51)	<0.001	9.09	(4.24-19.48)	<0.001

The dependent variable was set as a dichotomous variable coded as “1” if the participant had COVID-19 vaccination intent in the second wave survey and “zero” otherwise. The independent variable was the mean score of the five psychological antecedents.

All variables were placed in the model simultaneously, and the model was adjusted for educational attainment (university graduate or above/below) and annual personal income (<19,000 USD /19,000–38,000 /38,000–57,000/≥57,000).