DP002
COVID-19 Vaccine Acceptance among Parents in Japan

Mao YAGIHASHI1, Kei HIRAI1,2, Asako MIURA1,2
1Human Sciences Unit, Center for Infectious Disease Education and Research, Osaka University
2Osaka University Graduate School of Human Sciences

COVID-19 Vaccine Acceptance among Parents in Japan
Mao YAGIHASHI1, Kei HIRAI1, 2, Asako MIURA1, 2
Human Sciences Unit, Center for Infectious Disease Education and Research, Osaka University

1

Osaka University Graduate School of Human Sciences

2

Email:
yagihashi@cider.osaka-u.ac.jp
khirai@hus.osaka-u.ac.jp
asarin@hus.osaka-u.ac.jp

Corresponding Author
Asako MIURA

1. Purpose of the Study
Although vaccination is considered the most effective measure to prevent the spread of Coronavirus
Disease 2019 (COVID-19), people identified in the "anti-vaccine" camp hesitate or avoid vaccination,
raising a public health concern. In addition, many parents hesitate to vaccinate their children as theshort- and long-term effects of vaccinating young children are unknown.
We conducted questionnaire surveys and semi-structured interviews to investigate factors that influence
the parental decision regarding vaccination of children under the age of 18. We aim to makerecommendations for policies that promote the immunization of children and gain knowledge that aids
future public health campaigns.

2. Methods
2.1. Study Design
This collaborative study involved the University College of London (UCL) and Osaka University(OU). OU was responsible for the data collection, using a questionnaire and interviews, and analyzing
the content of interviews conducted in Japan. This study comprised a web survey (questionnaires) andonline interviews. At OU, the Ethics Committee of Osaka University Graduate School of Human Sciences
approved this study. Informed consent was obtained from participants on the first page of the web survey
and at the beginning of online interviews.
2.2. Participants
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The participants of this study were parents of children under the age of 18. Forty participants wererecruited after a screening process using the crowdsourcing system, CrowdWorks (CrowdWorks. Inc.
(CW), Shibuya, Tokyo, Japan).
2.3. Screening Procedure
First, we asked the pool of participants (n = 998) of our ongoing panel survey on COVID-19 initiatedin January 2020 about their willingness to participate in this study. Second, we administered a screening
survey to those who had responded in the affirmative and consented to participate (n = 742). The
screening survey was conducted by sending a direct mail (DM) on CW containing a link to the web
survey constructed by Qualtrics (Qualtrics International Inc., Seattle, Washington, and Provo, Utah). The
survey inquired about the following: individual's COVID vaccination status, family structure, presence
and number of children, age and COVID vaccination status of the oldest child, and willingness to beinterviewed. The survey’s duration was approximately one minute. Respondents were given an
honorarium of 15 yen, regardless of their decision to participate in the interview. Third, consenting
participants who had children below the age of 18 were selected as candidates (n = 96). Finally, 40
participants were selected after considering the vaccination status of both parents and children. The
selected candidates were contacted through DM via CW.
2.4. Excluding Criteria
Only Japanese residents were included in the questionnaire survey and interview. Those who
migrated from Japan after answering the survey were excluded, considering the differences in terms of
the situation, infection status, vaccination status, health insurance system, and administrative service. In
the demographic information, sexual orientation and ethnicity were excluded, considering thepsychosocial discomfort of asking Japanese people about these attributes.
2.5. Online Interview
We conducted the web survey and interviews via the videoconferencing system Zoom (Zoom Video
Communications, Inc., San Jose, California). The one-hour web meeting comprised two parts, thequestionnaire survey (approximately 15 min) and the interview (approximately 45 min). We began themeeting with a briefing, displaying a document explaining the study on the shared screen and obtaining
informed consent. Data were collected from 1st December 2021 to 31st January 2022.
2.5.1. Web Survey
We used the following questionnaires to assess the participants’ psychosocial profiles: The Strengthand Difficulties Questionnaire (SDQ; Goodman, 1994 & 1997; Moriwaki & Kamio, 2014), General Anxiety
Disorder-7 (GAD-7; Spitzer et al., 2006; Muramatsu, 2009), Patient Health Questionnaire-9 (PHQ-9;
Spitzer et al., 1999; Muramatsu, 2014), University of California Los Angeles Loneliness Scale (UCLA LS;
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Russell, 1978; Masuda et al., 2012), and Social Mistrust Scale (SMS; Wong et al., 2014; translated into
Japanese by our study group). The questionnaire survey was administrated online using Qualtrics.
During the response time, the microphone, camera, and screen sharing options were disabled.
2.5.2 Interview
Each 45-minute interview was conducted by a clinical psychologist. The participants wereaddressed by their nicknames. Due to ethical considerations, the camera and audio were turned on forboth the interviewer and interviewee to detect quickly any changes caused by psychological distress.
Only one participant refused to turn on the camera. No one withdrew from the interviews.
2.6. Statistical Analysis
Statistical Package for Social Science (SPSS) Statistics Version 21.0 (IBM, Armonk, NY) was used
for all analyses. We opted to use parametric tests consistently to compare the cut-off points or scores ofprevious studies. Therefore, all data are presented in the form of mean ± SD.
2.7. Content Analysis
The extraction of categories and the generation of superordinate categories for content analysis
were performed by six analysts to eliminate subjectivity. Five analysts were undergraduate or graduate
students of Psychology or related fields at the Graduate School of Human Sciences, Osaka University.
One was an Osaka University faculty member.
2.8. Ethics
This study was approved by the Osaka University Graduate School of Human Sciences Research
Ethics Committee (HB021-097). Informed consent was obtained from all participants at the beginning of
the video meeting and presented on the first page of the web survey.

3. Results

Forty people participated in this study (male = 13, female = 27, age = 39.8 ± 6.4), divided into 4groups according to combinations created based on vaccination status (Table 1). The status ofvaccinated/ unvaccinated parents depended on the interviewee’s vaccination status. Table 1 shows thenumber of members and the male-female ratio in each group were not balanced.

Table 1. Four groups formed according to vaccination status
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GroupsAbbr.

n (male:female)unvaccinated parents + unvaccinated children

UU

7 (1:6)

vaccinated parents + unvaccinated children

VU

12 (4:8)

vaccinated parents + vaccinated childrenVV

9 (3:6)

vaccinated parents + children planning to be vaccinatedVV'

12 (5:7)

3.1. Summary of psychological assessments
Table 2 displays the total and subscale scores.
Table 2. The descriptive statistics of psychosocial assessments
Questionnaires

SubscalesnMinimum

Maximum

value

value

Mean

SD

PHQ-9 sum

40

0

21

4.5

4.7

GAD-7 sum

40

0

20

3.7

4.4

SMS sum

24

0

13

6.3

3.1

UCLA LS sum

40

23

78

44.3

11.0

SDQ S18+ TDS

40

8

29

16.5

5.0

Emotional Symptoms

40

0

9

3.6

2.6

Problems in Conduct

40

0

5

1.6

1.1

Hyperactivity/Inattention

40

2

10

4.3

1.7

Peer Problems

40

4

11

7.0

1.7

Prosocial Behavior

40

2

10

5.8

2.1

40

0

22

9.7

5.9

Emotional Symptoms

40

0

9

2.0

2.1

Problems in Conduct

40

0

7

1.8

1.5

Hyperactivity/Inattention

40

0

10

3.7

2.6

Peer Problems

40

0

8

2.2

1.8

Prosocial Behavior

40

0

10

5.7

2.5

SDQ P4-17 TDS

Note. PHQ-9: Patient Health Questionnaire-9, GAD-7: Generalized Anxiety Disorder-7, SMS: Social Mistrust Scale, UCLA LS: Universityof California, Los Angeles Loneliness Scale, SDQ: Strength and Difficulties Questionnaire; TDS: Total Difficulties Score. SD: Standard
Deviation.

3.2. Severity of Depression and Anxiety
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We display the severity and distributions of depression and anxiety scores accessed using PHQ-9
and GAD-7 below (Figure 1-a, b, & Figure 2). The cut-off points for PHQ-9 and GAD-7 were establishedbased on a previous study (Muramatsu, 2014).
Figure 1-a. The severity of depression

30

PHQ-9 Score

25

26

20
15

9

10

3

5
0

non

mild

1

moderate moderate severe

1severeSeverity
Figure 1-b. The severity of Anxiety

35

GAD-7 Score

30

29

25
20
15

7

10
5
0

non

mild

3
moderate1
severeSeverity
Note. PHQ-9: Patient Health Questionnaire-9, Generalized Anxiety Disorder-7. The horizontal axis shows the severity and the vertical axis
shows the score. The numbers indicate the degrees in the graph.

Figure 2. The distribution of depression and anxiety
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25

20

Score

15

10

5

0

PHQ-9_sum

GAD-7_sum

Note. PHQ-9: Patient Health Questionnaire-9, Generalized Anxiety Disorder-7. The horizontal axis shows the severity and the vertical axis
shows the score. The red cross marks (×) indicate the mean score and the blue dots (〇) represent the raw data.

3.3. Reasons for getting/refusing vaccination among Parents and Children
First, a private contractor was hired to transcribe the interviews. Next, we conducted a content
analysis. We considered each interview as one coherent text and extracted 363 sentences based on four
categories of reasons: reasons for parents being vaccinated (A), for parents being unvaccinated (B), forparents who had their children vaccinated (C), and for parents whose children remained unvaccinated(D). Finally, the extracted sentences were coded and categorized by six analysts. Table 3 displays theclassification scheme.

6Table 3. The categories abstracted from interviews(A) Reasons for parents(B) Reasons for parents(C) Reasons for parents(D) Reasons for parents

being vaccinated

had their children

being unvaccinated

whose children remained

vaccinatedDecision making

Opinions from experts,

based onhealth care professionals,

informationand people engaged in

unvaccinatedLack of information

Lack of information

Distrust towards mass

Distrust towards mass

media

media

Acquiring and trusting anti--

vaccination--

vaccination information
Information from/discussion

-

-

-

-

Child's consent-

Child's lack of consent

Consideration ofConsideration of-Consideration ofadvantages andadvantages andadvantages anddisadvantages

disadvantages

disadvantages

Basic opinions

Not hesitant to be-

for vaccination

vaccinatedwith spouseIntuitive and emotional

More cautious about

refusal to be vaccinatedvaccinating children thanvaccinating themselves--

Aversion to injections

Aversion to injections

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Social impacts-（Reluctance towards

Reluctance towards

voluntary immunization）

voluntary immunization

Vaccinated after

Vaccinated afterUnvaccinated after

Vaccinated/Unvaccinatedconsidering vaccinationconsidering vaccinationconsidering the vaccination

after considering thestatus in the surroundings

status in the surroundings

status in the surroundings;

vaccination status in thei.e., no need to getsurroundings; i.e., if thevaccinated if people in theinfection is controlled, I will

surroundings are

not have my children

vaccinated.

vaccinated.

Concerns about school（Low impact of COVID-19-

infection

in real life ）Social disadvantages of--Occupational reasons-childrenPeer pressure

Peer pressure

Peer pressure backlash(Peer pressure backlash）

Concerns about infection in

-

-

-

-

-

-

partners and households
Concern about social
impact on surroundings
Social support

Accessibility of vaccination

Accessibility of vaccination--for vaccination--(Hassles in going to get-

vaccinated）--

Difficulty in decision making

Missed the opportunity toregarding vaccination

get vaccinated8Childcare concerns-(Childcare concerns）

-

-

-

-

Concerns about support
system for post-vaccination
emergencies

Opinions about

Infection prevention

Infection prevention--

COVID-19 andPreventing severe infection

Preventing severe infection--

its vaccination

Fear of infection

-

-

-

Expectations about vaccine-

Distrust of vaccines

Distrust of vaccines

Tolerance for adverse-

Concerns about adverse

Concerns about adverse

effects

effects

Concerns about medium- toConcerns about medium- tolong-term bodily effects

long-term bodily effects

Doubts about the speed of

Doubts about the speed ofregulatory approval

regulatory approval

-

-

-

-

Confidence in autoimmunity(Confidence in

effects
Peace of mind through-vaccination-

autoimmunity）
Note. Lower categories consisted of more than 2 cords; the categories in the parenthesis were those comprising only one cord.

93.4 Comparing categories of reasons
We compared the categories among the four reasons to understand the profiles of each reason andcontext properly. Therefore, we compared (A) with (B), (C) with (D), (A) with (C), and (B) with (D),respectively.
Reasons for parents being vaccinated (A) vs. reasons for parents having their children
vaccinated (B).
Commonalities. Regarding the reasons for vaccination of parents and children, the commonalities were
presented in terms of consideration of advantages and disadvantages, peer pressure, vaccination after
considering the vaccination status in the surroundings, prevention of infection, prevention of serious
illness, and accessibility of vaccination.
Differences. Differences between parents and their children based on reasons for vaccination concern
occupational reasons, school infection, and social disadvantage for the child. Parents were vaccinated
due to professional reasons, and they decided to vaccinate their children due to the fear of school
infection. Parents were also concerned about the social disadvantage of their children's incomplete
vaccination status, i.e., examinations, bullying due to non-vaccination, or isolation. Furthermore, thechild's consent was also cited as a reason that incentivized children’s vaccination.
Reasons for parents being unvaccinated (C) vs. Reasons for parents whose children
remained unvaccinated (D)Commonalities and differences. First, lack of information and distrust of mass media for (C) and (D)influenced informed decisions. The child's lack of consent and consideration of advantages anddisadvantages were present only in (D). Second, there were aversions to injections and reluctance tovoluntary immunization both in (C) and (D). These reasons were based on basic opinions about
vaccination. There was intuitive and emotional refusal to be vaccinated in (C), and there was morecaution about vaccinating children than parents themselves in (D), which accounts for the differences.
Third, there were unvaccinated after considering the vaccination status in the surroundings and no needto get vaccinated if people in the surroundings are vaccinated in (C). There was vaccinated or
unvaccinated considering the vaccination status of the surroundings; if the infection is controlled and I
will not have my children vaccinated in (D) with respect to social impact. Both (C) and (D) included peer
backlash. Fourth, regarding the social supports for vaccination, there were hassles of going to get
vaccinated, difficulty in decision making regarding vaccination, and childcare concerns in (C). Instead,
there were missed the opportunity to get vaccinated and concerns about support system for postvaccination emergencies in (D). Finally, regarding opinions about COVID-19 and its vaccination, distrustof vaccines, concerns about adverse effects, concerns about medium- to long-term bodily effects, doubt
about speed of regulatory approval, and confidence in autoimmunity were identified in categories (C) and(D).
10Reasons why parents were vaccinated (A) vs. Reasons why parents were unvaccinated (C).
Commonalities and differences. Many contradictory categories were obtained for (A) and (C). First,
informed decisions of the participants were dependent on opinions from experts, health care
professionals, and people engaged in vaccination in (A), and lack of information, distrust of mass media,
and acquiring and trusting anti-vaccine information accessed from Social Network System (SNS) in (C).
Second, the participants were not hesitant to be vaccinated in (A). There was intuitive and emotional
refusal to be vaccinated in (C) related to opinions about vaccination. However, there was an aversion to
injections in (C) but not in (A). Third, regarding the social impact, vaccinated after considering thevaccination status in the surroundings was identified in category (A), and unvaccinated after considering
the vaccination status in the surroundings, and no need to get vaccinated if people in the surroundings
are vaccinated in (C). Peer pressure was obtained in (A). In contrast, peer pressure backlash was
obtained in (C). Fourth, there was the accessibility of vaccination in (A), but there were hassles of goingto get vaccinated and difficulty in decision-making regarding vaccination in (C). Regarding the social
support for vaccination. Childcare concern was the only reason in common, found in both (A) and (C).
Finally, infection prevention and preventing severe infection were obtained in (A). In contrast, there wasconfidence in autoimmunity in (C) related to opinions about COVID-19 and vaccination. Subsequently,
there were expectations of the vaccine and tolerance for adverse effects (A) and distrust of vaccines andconcerns about adverse effects in (C). Finally, fear of infection and peace of mind through vaccination
were found in (A). In contrast, concerns about medium- to long-term bodily effects and doubts about the
speed of regulatory approval were found in (C).
Reasons for parents had their children vaccinated (B) vs. Reasons for parents had theirchildren unvaccinated (D)Commonalities. Consideration of advantages and disadvantages were obtained in both (B) and (D)despite the difference in contexts. Individuals in category (B) thought the advantages of vaccination
outweighed the disadvantages, and those in (D) thought that the disadvantages outweighed theadvantages. Parents made their decisions regarding their children’s vaccination after considering thevaccine status in the surroundings, but the contexts differed. After considering the surroundings, people
decided to get the vaccination for their children in (B) and to refuse it in (D).
Differences. Infection prevention, preventing severe infection, concerns about school infection, andsocial disadvantage of children were identified in category (B). Concern about adverse effects, distrust of
vaccines, lack of information, and distrust of the mass media were obtained in category (D).
Furthermore, there was the child's consent in (B) and the child's lack of consent in (D).

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4. Discussion and conclusion
This study aimed to identify factors that promoted or discouraged vaccination among parents ofchildren under the age of 18. Parents' and children's vaccination status and intentions may be influenced
by their infection status at the time and their eligibility for vaccination. The interviews in this study wereconducted from December 1, 2021, to January 31, 2022, when the infection situation in Japan was in adormant period, which was between the fifth and sixth wave, and when domestic adjustments were
underway for vaccinating children (to expand vaccination coverage) (See supplemental information, 5-1& 5-2).
In this study, we qualitatively analyzed how parents made decisions regarding COVID-19
vaccination in changing circumstances. As the COVID-19 situation is dynamic, people’s behavior is fluid.
Therefore, further research is needed to clarify factors that promote or discourage vaccination of parents
and children.

5. Supplemental Information
5.1. New coronavirus cases in Japan during the data acquisition period
There were very few new infections at the beginning of December 2021, when the web surveys andinterviews commenced. The number of new cases per day from late October to the middle of December
2021 was approximately the lowest during the spread of the new variant. However, it gradually
increased, starting in late December 2021, and it peaked at the end of January 2022 (See the figure
below; cited from the open data by the Ministry of Health, Labor, and Welfare in Japan,
https://www.mhlw.go.jp/stf/covid-19/open-data.html)

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100,000
90,00080,00070,00060,00050,00040,00030,00020,000

2020

2021

3/22

2/22

1/22

12/22

11/22

10/22

9/22

8/22

7/22

6/22

5/22

4/22

3/22

2/22

1/22

12/22

11/22

10/22

9/22

8/22

7/22

6/22

5/22

4/22

3/22

2/22

0

1/22

10,0002022

Change of the new coronavirus cases based on the open data by ministry of health, labor, andwelfare in Japan

5.2. Trends related to vaccination in Japan
Vaccination Coverage. Vaccination coverage, from 1st December 2021 to 31st January 2022, in Japan
was as follows: 1st 76.63%–77.24, 2nd 75.77%–76.70% 2nd, 3rd 0.00% (1560 until December 2) –3.32%. (We calculated the vaccination rate, referring to the website of the Japanese Cabinet Secretariat:
https://www.kantei.go.jp/jp/headline/kansensho/vaccine.html)
Vaccination eligibility. Initially, the target population of the COVID-19 vaccine was children older than
12 years of age and adults. At the beginning of November 2021, speculations on the regulatory
application of pediatric vaccination at and above age five became public. Later, in January 2022, thispediatric vaccination policy was approved in Japan.

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