Characteristics of participants in a public rubella antibody testing program conducted at a Japan professional football league venue

Abstract Background Hypothesizing that soccer‐associated public health campaigns influence men more than women, we investigated the characteristics and motivations of participants who received rubella antibody testing at a Japanese professional football league event. Methods This was a survey‐based cross sectional study, comparing the characteristics and motivations between men and women regarding rubella antibody testing. Results Free and convenient testing was the biggest behavioral influencer, but the information provided by healthcare professionals and athletes also played a strong motivating role. Men reported more influence from celebrity athletes than women. Conclusions Public health attention raised by celebrity athletes may facilitate rubella awareness among male spectators.

rubella antibody titers. 8 In addition, 10%-30% of women of childbearing age do not have antibody titers considered sufficient for pregnancy. 9 In collaboration with J-League, we provided rubella awareness activities before an official match, followed by free and voluntary rubella antibody testing for adult spectators. As part of this effort, Japanese celebrity soccer players assisted with rubella awareness activities via social networking platforms and print media.
As free public health testing at sports events is exceedingly rare in Japan, we surveyed the characteristics of spectators who received rubella antibody tests, exploring the behavioral influencers behind their motivation to receive testing. Hypothesizing that sports-associated campaign influenced men more than women, we also investigated whether there were gender differences in knowledge and motivations related to rubella.

| Respondents
Eighty-nine adult spectators underwent rubella antibody tests at the J-League FUJI XEROX SUPER CUP 2020 held on February 8, 2020, 10 to whom we mailed questionnaires and study consent forms, asking them to return the forms upon completion. The study protocol was approved by the Ethics Committee of St. Luke's International Hospital, Japan (Number: 19-R213).

| Questionnaires
We asked participants about their educational background, frequency of health care visits, and presence of partners and children. Using a four-point scale, we assessed participants' knowledge of rubella, congenital rubella syndrome, and rubella vaccine. Behavioral influencers that potentially influenced participants to receive a rubella antibody test were divided into five categories, each assessed on a four-point scale: (1) testing was free and convenient; (2) testing was recommended by a family mem-

| Statistical analysis
Descriptive statistics were used to summarize the data. We compared the baseline characteristics between genders using Fisher's exact tests for categorical variables and the Mann-Whitney test for continuous variables. Statistical significance was set as p < 0.05. All statistical analysis was performed using R Statistical Software (version 3.4.1; R Foundation for Statistical Computing).

| RE SULTS
Of 89 testing recipients, 38 (26 men; 68%) returned a completed questionnaire and consented to the study (response rate, 43%). The age of all respondents ranged from 28 to 56 years, with a mean of 40.0 years. Twenty-nine (76%) had a college education or higher, 24 (63%) had a partner, and 13 (34%) had children. With regard to knowledge of rubella, respondents were divided among those who had heard of it (34%), knew that it was prevalent (37%), and knew about both the outbreak and its symptoms (29%). Ninety-two percent of respondents considered "free and convenient" as an important factor for testing. Eighty-seven percent of respondents reported influence from information provided by healthcare professionals, and 65.7% reported influence from information provided by celebrity soccer players. By gender, men reported less knowledge of congenital rubella syndrome and demonstrated more influence from celebrity soccer players than women. There were no statistically significant differences between men and women regarding knowledge of rubella and its vaccine, or other behavioral influencers (Table 1).

| DISCUSS ION
Although this study is not intended to show the facilitating factors for taking the antibody test in subjects of the 5th phase rubella routine immunization program, but rather in the general population, free rubella antibody testing and information provided by healthcare professionals proved to be useful for most participants. The fact that men tended to report more influence from celebrity soccer players may help raise rubella awareness for male spectators in the J-League. Working with celebrity athletes, medical professionals might be able to have a positive impact on public health attention. 11 A previous study examining factors of participation in the rubella catch-up campaign in Japan found that male respondents who understood the government's recommendations were more likely to receive rubella antibody testing. 12 Another study of Japanese women showed that knowledge of rubella was one predictor of self-reported rubella vaccination status. 13 We also showed that men were less aware of congenital rubella syndrome. These studies suggested that, in order to promote antibody testing and vaccination, population-wide increases in infectious disease literacy are important. To this end, awareness-raising and educational activities against rubella continue to be needed.
Regarding limitations of our study, the response rate was low with a consequently small sample size; the interpretation of these results may be influenced by multiple biases, including observer and responder bias, in this exploratory research.

| CON CLUS ION
Free and convenient testing was the biggest influence, but the information provided by healthcare professionals and celebrity athletes were also major motivation, for spectators' getting antibody tests TA B L E 1 Characteristics of Japan's professional football league spectators (n = 38) receiving rubella antibody testing, and differences between men and women. at a sports event. Celebrity athletes' influence might be especially influential among male spectators.

ACK N OWLED G M ENTS
The authors wish to thank Shoji Fujimura, General Manager of Research & Study, Japan Professional Football League, for his kind support.

FU N D I N G I N FO R M ATI O N
The author TN was supported by research funding by LINK-J SCOOP 2019 (200 thousand yen) and ANA Wonder FLY (372 thousand yen). No other authors reported any financial disclosures.

E TH I C A L A PPROVA L
None.

PATI E NT CO N S E NT S TATE M E NT
Written informed consent was obtained from all individual participants included in the study. Strongly disagree 4 (10.5) 4 (15.4) 0 (0)

O RCI D
Note: The hemagglutination assay (HI) method was used to determine antibody titers against rubella (Denka Seiken Co, Ltd, Tokyo). Cutoff antibody titers for rubella were defined as ≦1:8 (on the HI assay). We sent the results of antibody titers to all participants and recommended those with negative results to receive rubella vaccination at a nearby medical institution. We compared the baseline characteristics between gender using the Fisher's exact tests for categorical variables and the Mann-Whitney test for continuous variables. A statistical significance was set as p < 0.05.