Norizuki et al. Environmental Health and Preventive Medicine
https://doi.org/10.1186/s12199-021-01002-7(2021) 26:77

RESEARCH ARTICLE

Environmental Health andPreventive Medicine
Open Access

Factors associated with adults’ actions toconfirm their own rubella immune status in
Japan’s drive toward rubella elimination:
Cross-sectional online survey of nonhealthcare workers in their 20s to 40s
Masataro Norizuki1,2, Ai Hori3 and Koji Wada1*

Abstract
Background: Rubella outbreaks occurred among adults in Japan in 2013-2014 and 2018-2019 due to immunity
gaps. In response and aiming at rubella elimination by 2020, the government introduced countermeasurescomprising supplementary immunization activities for voluntary testing of adult non-healthcare-related workers andvaccination of susceptible individuals. However, as of October 2020, rubella immunity testing and vaccination rates
remained low. This study was conducted to identify factors associated with adults voluntarily confirming theirrubella immune status, to help develop effective promotion activities for hard-to-reach and left-behind populations.
Methods: In this cross-sectional study, a general population sample of non-healthcare workers aged 20-49 years inJapan completed an online survey in November 2020. Univariate analysis was performed to examine associations ofspecific actions taken to confirm rubella immune status with social background characteristics, knowledge ofrubella, and attitude to testing and vaccination. Log binomial regression analysis was performed to explore theassociations following adjustment for social background characteristics.
Results: Among 1,854 respondents (927 men, 927 women), only 23.4% of men and 39.4% of women in their 20s to
40s have taken some action related to rubella prevention. Three major factors were associated with the targeted
population having taken voluntary action: (1) knowing about testing for confirmation of immunity status (adjusted
odds ratio [AOR] 4.29 men, 2.89 women), the rubella outbreak in 2013 among men in their 20s to 40s (AOR 2.79
men, 1.64 women), and congenital rubella syndrome (AOR 1.89 men, 3.10 women); (2) having acquaintances who
were vaccinated against or tested for rubella (AOR 2.98 men, 1.95 women); and (3) having a positive attitude
toward influenza vaccination (AOR 2.48 men, 1.83 women). Marriage, desire for pregnancy, and having children
were weakly associated with taking action.

* Correspondence: kwada-sgy@umin.ac.jp
1
Graduate School of Medicine, International University of Health and Welfare
Graduate School, 4-1-26 Akasaka, Minato, Tokyo 107-8402, Japan
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Norizuki et al. Environmental Health and Preventive Medicine(2021) 26:77

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Conclusions: Currently, insufficient voluntary action is being taken by high-risk adult populations to close theidentified immunity gaps. In this last mile to rubella elimination, our findings and suggested potential interventions
via annual health check-ups and occupational health and public health initiatives could prove helpful in developing
further countermeasures that actively promote and implement supplementary immunization activities targeting all
adult generations.
Keywords: Rubella, Vaccine-preventable disease, Knowledge, Attitude, Immunization policy, Supplementary
immunization activities

Background
Population immunity of at least 83% is needed toachieve herd immunity and interrupt transmission of endemic rubella virus [1]. Routine immunization withrubella-containing vaccine has dramatically decreased
infections, and rubella has been successfully eliminatedin some countries and regions [2]. However, even insome countries that have achieved high vaccination
coverage in childhood, outbreaks have occurred among
adults [3, 4]. In Japan in 2013, a rubella outbreak occurred among the working-age population that had notbeen previously vaccinated; 14,344 adults mostly in their
20s to 40s were infected and 45 cases of congenital rubella syndrome (CRS) were recorded [5–7].
This 2013 outbreak was due to immunity gaps. In
1977, the government had started a rubella vaccination
program for adolescent females (age 12-15 years) to prevent CRS and the policy continued until 1995, when universal infant immunization was introduced. Vaccinations
programs started in 1989 for the first dose of measlesrubella vaccine and in 2006 for the second dose [8]. The
historical routine immunization of adolescent females,
subsequent introduction of childhood immunization,and lack of supplementary immunization activities(SIAs) for testing of adults resulted in immunity gaps
among adults born before April 1, 1990 who were notinfected with rubella naturally and who did not have theopportunity to be vaccinated twice.
As a countermeasure to the 2013 outbreak, from 2014
the government introduced voluntary-based SIAs for
adults. To promote vaccination uptake before pregnancy
and prevent CRS cases, the government started providing financial support to women of childbearing age andtheir partners for antibody testing [9]. Despite these efforts, another outbreak occurred in 2018-2019 mainly
among rubella-susceptible adult males [10], and 5 CRS
cases were reported [11]. As an additional countermeasure and to try to meet Japan’s target of rubella elimination by 2020, in 2019 the government also began
testing adult males for immunity and vaccinating males
born between April 2, 1962 and April 1, 1979, who had
no opportunity to receive routine vaccination against rubella and who were found by an antibody test to have alower seroprevalence of rubella-specific antibody thanother age groups [11, 12]. However, as of October 2020,
among the targeted adult male population for example,
only 16% ( 2,491,478/15,374,162) had been tested for rubella immunity (1,245,330 in 2019 and 1,246,148 in2020) [12].
In countries close to eliminating rubella like Japan,
vaccination needs to reach all susceptible adults. This requires that individuals confirm their own immune status
for rubella, by checking their documented vaccination
history or taking a rubella antibody test and getting vaccinated as necessary. However, because testing and vaccination strategies in Japan are voluntary, there isconcern that SIA coverage is lower than needed toachieve herd immunity and eliminate rubella. Also, although far fewer rubella cases were reported in 2020
compared with previous years (100 in 2020 [13] vs 2,946
in 2018 [11] and 2,306 in 2019 [11]), social distancing,
universal masking, and additional hygiene measures introduced during the novel coronavirus disease 2019
(COVID-19) pandemic likely contributed to this dramatic decrease, and another rubella outbreak may bepossible when society opens up again.
We conducted this study in late 2020 to evaluate thelatest progress in promoting high-risk adults to voluntarily confirm their rubella immune status. We investigatedsociodemographic characteristics and attitudes associated with voluntary action in order to identify ways tohelp policy makers promote action among high-risk
adults with lower immunity, especially those in their 20s
to 40s and in hard-to reach or left-behind populations.

Methods
Participant enrollment

This cross-sectional study was conducted with a general
population sample in Japan. Participants were recruitedby an online survey company (Macromill, Inc. Tokyo,
Japan). All registered candidates had agreed to participate in online surveys and could withdraw consent at
any time, and additionally read the study information
before specifically agreeing online to participate in thisstudy, with the option to withdraw up until submitting
their answers. Thus, written consent was not obtained.
The institutional ethics committee approved thisprotocol.

Norizuki et al. Environmental Health and Preventive Medicine(2021) 26:77

Inclusion criteria were age 20-49 years and agreement
to participate. Individuals were excluded if they wereregistered as healthcare-related workers according to 12
occupation categories and 43 subcategories used by thesurvey company (e.g., doctors, nurses, pharmacists, administrative staff working in hospitals, and employees ofhealthcare companies in order to better represent thegeneral population, because healthcare workers tend tobe vaccinated).
In November 2020, from a list of 10 million individuals, the survey company randomly selected 6,000 eligible participants—1,000 men and 1,000 women in threedifferent age groups (20-29, 30-39, and 40-49 years)—and invited them to participate. Registrants were provided financial incentives for their participation. Sample
size was calculated based on a margin of error of 6%, assuming 50% of the target population in each stratum(3,500,000 men and 3,500,000 women), with 95% confidence intervals, to obtain 267 per stratum. We decided
on a sample size of 300 for each of the six strata, and recruitment was ended once approximately 1,800 participants agreed to participate (Figure 1). Participants who
did not answer all of the questions or answered in too
short a time were excluded from the final analysis.
Questionnaire data collection
Demographic information

The survey company provided basic demographic information on age, sex, marital status, and having children
or not. Questionnaire items included additional basic
demographic information, highest education level (highschool or lower/junior college,/university/graduate
school/no answer), and desire for pregnancy (“Are you,or your partner, pregnant or plan to get pregnant?”[Yes/No/I don’t know]).
Knowledge about rubella

To evaluate knowledge of rubella, based on current
strategy and the government’s promotion for rubellaelimination, we created three items on knowledge about
the testing and vaccination strategy, the 2013 rubella
outbreak, and CRS. Participants answered whether theyknew or did not know the following information: “A
blood test (antibody test) can be done to determine
whether someone has been vaccinated against rubella or
has previously had rubella” (I knew that/I did not knowthat); “In 2013, there was a rubella epidemic, mainly
among men in their 20s to 40s” (I knew that/I did notknow that); and “Women who are infected with rubella
during pregnancy may give birth to children with congenital rubella syndrome. (Congenital rubella syndrome:difficulty hearing, heart deformities, sight problems, delayed mental or physical development, other congenital
disorders)” (I knew that/I did not know that).

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Attitude to testing and vaccination

We created two questions to reveal attitude toward
testing and vaccination. To determine whether participants’ acquaintances had been vaccinated against rubella, the first question asked, “Since the 2013
epidemic, have any of your acquaintances (people you
can contact by phone or email) had a rubella blood
test (antibody test) or been vaccinated for rubella?”(Yes/No/I don’t know). To determine acceptance ofvaccination, the second question asked, “Do you get
an influenza vaccine?” (Every year/Almost every year/
Sometimes/Never/I don’t know).

Actions to confirm rubella immune status

To identify whether respondents had taken action toconfirm their rubella immune status, we asked the following three questions about action taken after the 2013
rubella outbreak in Japan: “Since the 2013 rubella epidemic, have you checked your Maternal and Child
Health Handbook or other vaccination records to confirm whether you have been vaccinated for rubella?”(Yes/No/I don’t know); “Since the 2013 rubella epidemic,
have you had a blood test (antibody test)?” (Yes/No/I
don’t know); and “Since the 2013 rubella epidemic, haveyou had a rubella vaccination?” (Yes/No/I don’t know).
We combined the answers to these three questions togenerate a binary outcome variable; if respondents answered affirmatively to any of the three questions, wedefined them as having taken action to confirm their rubella immune status.

Statistical analysis

We performed univariate analysis using Pearson’s chisquared test to examine the potential relationship between each of the three actions taken to confirm rubella
immune status and social background, knowledge, or attitude. Log binomial regression analysis was then performed to explore the associations with adjustment forsocial background characteristics. All demographic variables were included in the primary model and all wereshown to be significant in univariate analysis (P < 0.05)
in this study or in previous studies [14–21]. The final
model was adjusted for all variables. IBM SPSS Statistics
19 software (IBM Corporation, Armonk, NY) was used
for all analysis.

Ethical considerations

The study protocol was reviewed and approved by the
Ethics Committee of the International University of
Health and Welfare, Tokyo, Japan (approval number 18Im-010).

Norizuki et al. Environmental Health and Preventive Medicine(2021) 26:77

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Fig. 1 Participant flow in this cross-sectional online survey of non-healthcare workers in their 20s to 40s. Participants were enrolled from among
non-healthcare workers aged 20 to 49 who had registered with an online survey company (Macromill, Inc. Tokyo, Japan). The survey company
sent a message to 6,000 randomly selected registrants comprising 1,000 men and 1,000 women in three different age groups (20-29, 30-39, and40-49 years). Recruitment was ended once approximately 1,800 participants agreed to participate, and ultimately 309 men and women in thethree different age groups participated

Results
Participants

A total of 1,854 participants, 927 men and 927 women,
participated in the web survey, which was conducted in
mid-November 2020. Table 1 shows the participants’sociodemographic characteristics and their reported actions to confirm their rubella immune status. More than
70% of female participants reported knowing about CRS,
compared with less than half of male participants. Morewomen than men had taken one or more of the threelisted actions to confirm their rubella immune status(39.4% and 23.4%, respectively). Rubella antibody testing
was the most common measure to confirm immune status among men and documented vaccination history

was the most common measure to confirm immune status among women, with no significant difference foundbetween the sexes.
Binomial logistic regression analysis

Table 2 shows the prevalence of action taken to confirm
immune status for rubella prevention stratified by sociodemographic background among men and women.
Overall, 66.0% of men and 74.8% of women who had acquaintances who got vaccinated or tested for rubella
took action to confirm own immune status for rubella.
Among the different age groups, only 25.2% of women
aged 40-49 years took action to confirm their rubella immune status.

Norizuki et al. Environmental Health and Preventive Medicine(2021) 26:77

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Table 1 Sociodemographic characteristics of the 1,854 participants in this online survey (November 2020)
Men

Women

n = 927(%)

n = 927(%)

Having knowledge about
Confirmation of immune status by testing259(27.9)

428(46.2)

2013 rubella outbreak in men in their 20s-40s

279(30.1)

358(38.6)

Congenital rubella syndrome393(42.4)

677(73.0)

Having acquaintances who got vaccinated or tested for rubellaYes

94(10.1)

147(15.9)

No/ Don’t know

833

(89.9)

780(84.1)

Every year

184

(19.8)

185(20.0)

Almost every year

134

(14.5)

143(15.4)

Sometimes

223(24.1)

234(25.2)

Never

365(39.4)

350(37.8)

Don’t know

21

(2.3)

15

(1.6)

Married342(36.9)

492(53.1)

Single585(63.1)

435(46.9)

Yes

260(28.0)

306(33.0)

No/ Don’t know

667

(72.0)

621(67.0)

Yes

281(30.3)

400(43.1)

No/ Don’t know

646

(69.7)

527(56.9)

20-29

309(33.3)

309(33.3)

30-39

309(33.3)

309(33.3)

40-49

309(33.3)

309(33.3)High school or lower

300(32.4)

292(31.5)

Junior college

117(12.6)

258(27.8)

University

431(46.5)

342(36.9)

Graduate school

59

(6.4)

26

(2.8)

No answer

20

(2.2)

9

(1.0)

Receiving influenza vaccination

Marital status

Desire for pregnancy

Having a child/children

Age, years

Highest education level

Taken voluntary action for rubella prevention after 2013 rubella outbreak
Any

217

(23.4)

365(39.4)

Vaccination history*

112(12.1)

257(27.7)

Underwent antibody testing129(13.9)

209(22.5)

Vaccination for rubella

106(11.4)

148(16.0)*Confirmed more than two times from documented vaccination history, such as the Maternal and Child Health Handbook

Table 3 shows the associations found between sociodemographic factors and action taken to confirm rubella
immune status among men and women, as determinedby binomial logistic regression.
Men and women, but especially men, who knew that testing can confirm immune status were significantly more

likely to have taken action to confirm their rubella immune
status (men: adjusted odds ratio [AOR] 4.29, 95% confidence
interval [CI] 6.06-11.93; women AOR 2.89, 95% CI 2.004.18). Similarly, both men and women who knew about the
rubella outbreak in 2013 and about CRS were significantly
more likely to have taken action to prevent rubella infection.

Norizuki et al. Environmental Health and Preventive Medicine(2021) 26:77

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Table 2 Prevalence of action for rubella prevention stratified by sociodemographic background among working-age men and
women
Men

Women

Action for rubella
prevention

No action for rubella
prevention

Action for rubella
prevention

No action for rubella
prevention

n = 217(%)

n = 710(%)

n = 365(%)

n = 562(%)

Confirmation of immune status by testing138(53.1)

121(46.7)

256(59.8)

172(40.2)

2013 rubella outbreak in men in their 20s-40s

131(47.0)

148(53.0)

191(53.4)

167(46.6)

Congenital rubella syndrome160(40.7)

233(59.3)

328(48.4)

349(51.6)

Having knowledge about

Having acquaintances who got vaccinated or tested for rubellaYes62(66.0)

32(34.0)

110(74.8)

37(25.2)

No/ Don’t know

155

(18.6)

678(81.4)

255(32.7)

525(67.3)

Every year

78

(42.4)

106(57.6)

102(55.1)

83(44.9)

Almost every year41

(30.6)

93(69.4)

72(50.3)

71(49.7)

Sometimes

50(22.4)

173(77.6)

97(41.5)

137(58.5)

Never

46(12.6)

319(87.4)

92(26.3)

258(73.7)

Don’t know

2

(9.5)

19

(90.5)

2(13.3)

13(86.7)

Married121(35.4)

221(64.6)

242(49.2)

250(50.8)

Single96(16.4)

489(83.6)

123(28.3)

312(71.7)

Receiving influenza vaccination

Marriage

Desire for pregnancy
Yes81(31.2)

179(68.8)

148(48.4)

158(51.6)

No/ Don’t know

136

(20.4)

531(79.6)

217(34.9)

404(65.1)

Yes

108(38.4)

173(61.6)

211(52.8)

189(47.3)

No/Don’t know

109

(16.9)

537(83.1)

154(29.2)

373(70.8)

20-29

64(20.7)

245(79.3)

124(40.1)

185(59.9)

30-39

64(20.7)

245(79.3)

163(52.8)

146(47.2)

40-49

89(28.8)

220(71.2)

78(25.2)

231(74.8)

Having a child/children

Age, years

Highest education level
High school or lower

53(17.7)

247(82.3)

88(30.1)

204(69.9)

Junior college

26(22.2)

91(77.8)

106(41.1)

152(58.9)

University

119(27.6)

312(72.4)

153(44.7)

189(55.3)

Graduate school17(28.8)

42(71.2)

16(61.5)

10(38.5)

No answer2(10.0)

18(90.0)

2(22.2)

7(77.8)

Men and women who took action to confirm their rubella immune status were more likely to have acquaintances who had received a rubella vaccination or hadtaken the antibody test (men: AOR 2.98, 95% CI 1.705.23; women: AOR 2.95, 95% CI 1.84-4.71). Both men
and women who got an influenza vaccination every year
were more likely to take action compared with those
who never got an influenza vaccination (men: AOR 2.48,
95% CI 1.47-4.17; women: AOR 1.83, 95% CI 1.17-2.86).

Women with one or more children were significantly
more likely to have taken action to confirm their rubella
immune status (AOR 2.05, 95% CI 1.28-3.30), but only aweak association was seen among men (AOR 1.73, 95%
CI 0.93-3.22).
Both being married and wanting to get pregnant
tended to be associated with having taken action to confirm immune status in univariate analysis; however, thesignificance was weak after multivariate adjustment inNorizuki et al. Environmental Health and Preventive Medicine(2021) 26:77

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Table 3 Statistical associations between action for rubella prevention and sociodemographic background
Men

Women

Crude
OR

(95% CI)

Adjusted
OR(95% CI)

Crude
OR(95% CI)

Adjusted
OR(95% CI)

Confirmation of immune status by testing

8.50(6.06-11.93)

4.29(2.88-6.38)

5.33(4.00-7.10)

2.89(2.00-4.18)

2013 rubella outbreak in men in their 20s-40s

5.78(4.17-8.02)

2.79(1.88-4.14)

2.60(1.98-3.41)

1.64(1.16-2.34)

Congenital rubella syndrome

5.75(4.09-8.08)

1.89(1.24-2.89)

5.41(3.70-7.91)

3.10(1.94-4.95)

2.98(1.70-5.23)

6.12(4.10-9.14)

2.95(1.84-4.71)

Having knowledge about

Having acquaintances who got vaccinated or tested for rubella
Yes

8.48

No/ Don’t know

Ref(5.35-13.44)

Ref

Receiving influenza vaccination
Every year

3.20

(2.26-4.52)

2.48(1.47-4.17)

2.24(1.62-3.10)

1.83(1.17-2.86)

Almost every year

1.55

(1.03-2.31)

1.49(0.82-2.70)

1.70(1.19-2.43)

1.53(0.94-2.48)

Sometimes

0.93(0.65-1.33)

1.55(0.93-2.60)

1.12(0.83-1.52)

1.58(1.04-2.40)

Never

Ref

Don’t know

0.38

(0.08-1.46)

0.68(0.11-4.36)

Ref
0.23

(0.05-1.04)

1.60(0.32-8.12)

Married

2.79(2.04-3.80)

1.03(0.56-1.91)

2.46(1.87-3.23)

1.39(0.93-2.06)

SingleRef(1.32-2.30)

1.39(0.93-1.71)(2.06-3.55)

2.05(1.28-3.30)

Marriage

Ref

Desire for pregnancy
Yes

1.77

No/Don’t know

Ref(1.28-2.44)

1.54(0.98-2.41)

1.74
Ref

Having a child/children
Yes

3.08

No/ Don’t know

Ref

(2.24-4.22)

1.73(0.93-3.22)

2.70
Ref

Age, years
20-29

Ref

30-39

0.79

(0.57-1.10)

0.83(0.49-1.39)

Ref
2.30

(1.74-3.04)

1.11(0.73-1.68)

40-49

1.55

(1.13-2.12)

1.25(0.72-2.15)

0.39(0.29-0.53)

0.17(0.10-0.29)

Highest education level
High school or lower

0.61(0.43-0.86)

0.85(0.54-1.33)

0.56(0.42-0.75)

0.83(0.56-1.24)

Junior college

0.93(0.58-1.47)

1.06(0.58-1.92)

1.10(0.82-1.48)

1.11(0.73-1.68)

University

Ref

Graduate school

1.35(0.75-2.43)

0.85(0.40-1.82)

2.53(1.14-5.64)

2.51(0.94-6.68)

No answer

0.36(0.08-1.55)

1.10(0.20-6.20)

0.44(0.09-2.12)

0.53(0.80-3.44)

Ref

All listed variables were adjusted for in the final model.
OR, odds ratio; CI, confidence interval; Ref, reference

men and women. Women aged 40-49 years were lesslikely to have taken action to confirm their rubella
immune status compared with women aged 20-29
years (AOR 0.17, 95% CI 0.10-0.29), whereas men
showed no significant difference between the two age
groups (AOR 1.25, 95% CI 0.72-2.15). Highest education level showed no significant association with taking action.

Discussion
This study revealed that, as of late 2020, there is currently insufficient voluntary action being taken by highrisk adults in the Japanese general population (excluding
healthcare-related workers) to confirm their rubella immune status: only 23.4% of men and 39.4% of women in
their 20s to 40s have taken some action related to rubella prevention. Thus, our findings indicate that there isNorizuki et al. Environmental Health and Preventive Medicine(2021) 26:77

still some way to go in achieving rubella elimination in
Japan.
The first of the three major factors we found to be associated with the targeted population having taken voluntary action to check their rubella immune status washaving knowledge about testing for confirmation of immunity status, about the rubella outbreak in 2013 among
men in their 20s to 40s, and about CRS. It has been reported that knowledge about vaccine-preventable disease
is closely associated with uptake of the influenza [15,16], measles-rubella containing [22, 23], hepatitis A [24],and pertussis [25] vaccines. In the present study, knowledge that testing can confirm immune status showed astrong association with taking voluntary action among
both men and women (men: AOR 4.29, 95%CI 6.0611.93; women AOR 2.89, 95% CI 2.00-4.18). This suggests that Japan’s test and vaccination strategy has successfully prompted some of those reached by thepromotion to actually take action. Further evidence thatJapan’s current strategies are working are our findingsthat working-age men have become more aware of theirrole in CRS following the 2013 outbreak. An effective
intervention to reach more of the 20- to 40-year-old target population could involve providing further information in the workplace about rubella the need to check
immune status, and how to check it, via posters, pamphlets, or possibly occupational health activities insidelarger companies.
The second factor that we found to be associated withtaking voluntary action was having acquaintances who
were vaccinated against or tested for rubella, and this association was found for both men and women. This is inagreement with the results of previous online surveys
about rubella in Japan that reported the association for
vaccination [14] and testing [17] of an acquaintance.
Learning that a close acquaintance has been vaccinatedor tested may instill a sense of security and highlight thebenefits of taking action, which may be an effective strategy in collectivist societies like Japan [26]. Given that
promotion activities through social networking sites
such as Twitter and Facebook [27, 28] and through commercial and social marketing have been shown to be effective for vaccine uptake, activities involving familiar
people might also be an effective strategy. Moreover, potential interventions could, for example, involve interested employees voluntarily sharing their experiences ofvaccination during promotional activities run by occupational health personnel or encouraging people to share
their experiences of testing or vaccination with friends
through social networking service (SNS).
Lastly, among both men and women, getting vaccinated every year against influenza was associated withtaking voluntary action to confirm rubella immunity,
compared with never having been vaccinated against

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influenza. These findings are in agreement with otherstudies that have reported the association of annual influenza vaccination behavior with vaccine uptake [15, 16,18]. People who have influenza vaccinations every year
are likely to worry less about the side effects of the vaccine, be keenly interested in medical care, and have easy
access to it. Therefore, it is important that promotions
are targeted to reach people who are not interested or
do not have easy access to medical care. A possible
workplace-related intervention could be to include
measurement and explanation of rubella antibody titerat the annual medical check-ups offered by companies
in compliance with the labor law. This strategy could
reach working-age company employees who are not interested in seeking out medical information, enablingthem to easily confirm their immune status.
The life course events of marriage, desire for pregnancy, and having children were associated with taking
voluntary action to confirm rubella status, albeit weakly
in this study. Getting married tended to be associatedwith such action among men in the univariate analysis(OR 2.79, 95% CI 2.04-3.80) but not after multivariate
adjustment (AOR 1.03, 95% CI 0.56-1.91), and men
tended not to be interested in rubella before getting
married but were more interested after getting married(AOR 1.03, 95% CI 0.56-1.91). An online study of thegeneral adult population in 2014 also reported voluntaryaction was strongly associated with getting married [14].
We found that desire for pregnancy and having children
showed weak associations with taking action, although
the previous 2014 study found a strong association withdesire to get married [14]. Also, a recent study conducted in 2020 with Japanese men aged 41-47 years
found no association between partner’s current desire
for pregnancy and undergoing rubella antibody testing(AOR 0.98, 95% CI 0.87-1.11) [17]. Because all pregnant
woman are routinely tested for rubella antibody as partof antenatal care in Japan, experience of pregnancy is a
confounder in women and is one of the reasons for thehigher OR seen for women with children. Overall, ourfindings indicate that the switch from measures centeredon pregnant women and their partners to measures centered on men in 2019 is having a positive impact, whichis encouraging, but we need to reach more men to encourage them to take voluntary action to confirm theirrubella immune status.
Surprisingly, we found that women in their 40s weresignificantly less likely to have taken voluntary action toconfirm rubella immune status than those in their 20s.
Current promotion activities mainly target pregnant
women and men in their 40s, and the free testing andvaccination policy does not cover women without desire
for pregnancy. Interest in rubella prevention has clearly
fallen among women in their 40s. In addition, a recent

Norizuki et al. Environmental Health and Preventive Medicine(2021) 26:77

report from the National Institute of Infectious Diseases
indicates that seroprevalence is decreased among those
aged 55-69 [29]. It is therefore necessary to design a system that allows all generations to confirm their own immunity with no one left behind.
We did not find an association between highest education level and taking action to confirm rubella immune
status. There have been studies that have found an association between education level and vaccine intake—in
the Bahamas [19], Lebanon [20], and United States[21]—and those that have found no such association—in
Canada [30] and Japan [22]. The high literacy rate, easy
access to written information, and high education level
among all generations in Japan suggests that promotion
activities can make good use of written information.
It seems that more men and women in their 20s to
40s have taken action as of late 2020 compared with
2013, when around 25% of women and men with desire
for pregnancy but just 7.3% of women and 2.9% of men
without a current desire for pregnancy had been tested
for rubella antibody or vaccinated against rubella [14].
Even though our findings in late 2020 indicate that still
only 39.4% of women and just 23.4% of men had takensome action to confirm their immunity, these are moreencouraging rates, especially among women. Therefore,
it seems then that the government’s testing and vaccination strategy that started targeting those with desire forpregnancy and their family members in 2019 is working
to some extent [31] to close this identified immunity
gap. This would also explain the gap in taking action between women and men in our study. It is important tonote, however, that a recent survey in Japan reported
that only 21.3% of men had actually been tested for rubella antibody [32]. So, while our study indicates thatthe government’s promotion activities have been reaching the targeted populations, there are still insufficientnumbers of people taking the necessary preventive action to eliminate rubella in the very short term (originally 2020). Further strategies involving, for example, theannual medical check-ups, collaborations in occupational health activities, and encouragement to share experiences with friends through SNS are needed topromote action among those at high risk of rubella infection as well as hard-to-reach and left-behind
populations.
Our study had some limitations. First, because data
were obtained from a randomly selected online survey
population, our findings cannot be considered representative of the general Japanese population as a whole. Second, self-report bias and selection bias may haveresulted in overestimation of the results, although giventhat the targeted age group in their 20s to 40s tends tobe familiar with information technology and to haveinternet access, we believe this did not adversely affect

Page 9 of 10

our primary objective of identifying factors associatedwith their participation in the SIAs. Third, this was across-sectional study, so we cannot infer causal relationships. Lastly, we did not consider the potential influenceof the relationship between the rubella outbreaks andvariation in efficacy of the live rubella vaccine acrossyears. However, Japan does have strict quality control
standards in place for vaccines [33]. Despite these limitations in study design, we believe that our up-to-date survey results are important to policy makers in deciding
how to further accelerate measures for the eliminationof rubella in Japan.

Conclusion
Relying on voluntary action to confirm rubella immunity
is currently not a sufficient strategy to reach herd immunity needed for rubella elimination. The main drivers
for high-risk working-age adults to confirm their rubella
immune status in Japan are (1) having knowledge about
confirmation of immunity through testing, the 2013 rubella outbreak, and CRS, (2) having acquaintances who
have had a rubella vaccination or test, and (3) having a
positive attitude toward influenza vaccination. In thislast mile to rubella elimination, the government should
actively promote and implement SIAs to close the identified immunity gaps as well as provide additional ways
for adults to easily check their rubella immune status
and understand why it matters, such as via annual healthcheck-ups and occupational health and public health initiatives, utilizing digital technology to help achieve this.
Abbreviations
AOR: adjusted odds ratio; CI: confidence interval; COVID-19: novel
coronavirus disease 2019; CRS: congenital rubella syndrome; OR: Odds ratio;
Ref: Reference; SIAs: supplementary immunization activities; SNS: social
networking service Social networking service
Acknowledgements
We would like to thank Caryn Jones of ThinkSCIENCE (Tokyo, Japan) for
assistance with writing and editing the manuscript.
Authors’ contributions
MN was responsible for the design, analysis, interpretation, and drafting of
the manuscript. AH and KW revised the manuscript. All authors wereinvolved in drafting the article or revising it critically for important
intellectual content and have read and approved the final version of themanuscript.
Funding
This work was supported by a grant from the National Center for Global
Health and Medicine (30-6) and Japan Society for the Promotion of Science
KAKENHI (20K10467). The sponsors had no role in study design, in thecollection, analysis, or interpretation of data, in the writing of the report, orin the decision to submit the article for publication.
Availability of data and materials
The datasets used and analyzed during the current study are available fromthe corresponding author on reasonable request.

Norizuki et al. Environmental Health and Preventive Medicine(2021) 26:77

Declarations
Ethics approval and consent to participate
The study protocol was reviewed and approved by the Ethics Committee of
the International University of Health and Welfare, Tokyo, Japan (18-Im-010).
The participants consented to the online survey company’s policy forparticipation.
Consent for publication
Not applicable.

16.

17.

18.

Competing interests
The authors declare that they have no competing interests.
19.
Author details
1
Graduate School of Medicine, International University of Health and Welfare
Graduate School, 4-1-26 Akasaka, Minato, Tokyo 107-8402, Japan. 2Bureau ofInternational Health Cooperation, National Center for Global Health andMedicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan. 3Department of
Global Public Health, University of Tsukuba, 1-1-1 Tennodai, Tsukuba
305-8577, Japan.

20.

21.
Received: 31 May 2021 Accepted: 28 July 2021

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