Study design

This study is a secondary qualitative data analysis of an original nationwide research project on adolescent sexual health and rights initiatives in South Korea. We used a descriptive exploratory qualitative approach, which is useful for summarizing and understanding an area of interest [19], and allows for the contextualization of the topic. The study follows the Standards for Reporting Qualitative Research (SRQR) guidelines [20] for qualitative research studies (S1 File).

Setting and participants

A purposive sampling strategy was used initially to recruit survey participants from an online community of mothers in each of the districts in Seoul, the capital city of Korea. These online communities are interactive channels in which mothers share concerns about raising and educating children [21, 22]. Recruitment announcements were posted on the “announcements” board of the websites. To find additional eligible interviewees, we also used a snowball sampling approach. We asked the participants who were already recruited to recommend other contacts who fit the eligibility criteria and might be potentially willing to be interviewed. Participants were eligible to participate in the study if they were mothers of middle school-aged male adolescents (the equivalent of 7^th– 9^th grades in the United States) who had not received any doses of the HPV vaccine at the time of the interview, lived in one of the 25 districts in Seoul, completed an initial baseline survey and consented to be re-contacted. The study protocol was approved by the Institutional Review Board at Seoul National University (IRB No. 2106/003-013). Written informed consent was obtained from each participant prior to the interview. Each participant was compensated with a $30 e-gift card for their participation in the study.

Inclusivity in global research

Additional information regarding the ethical, cultural, and scientific considerations specific to inclusivity in global research is included in S1 Checklist.

Data collection

One-on-one semi-structured interviews were conducted via telephone due to COVID-19 restrictions. The interviews were conducted between August and December 2021 at a time convenient for the participants and lasted an average of 45 minutes The interviews were conducted by the first author, who was experienced in qualitative research and remained neutral and nonjudgmental. The interview guide used in this study was developed based on available literature [23–25] that addressed conceptual frameworks of the health belief model and the socio-ecological model. The main questions asked in the referenced studies were: 1) What is your view on vaccinating boys against HPV? 2) What are the reasons for not vaccinating your son? Validated interview questions designed for parents of daughters were adapted by replacing daughters with sons. The interview guide for the present study included 10 open-ended questions concerning mothers’ attitudes and beliefs about HPV and HPV vaccination. Mothers were asked to offer their thoughts regarding the HPV vaccine, their opinion on vaccinating boys against HPV, and their reason for delaying or refusing HPV vaccination for their sons. We continued to interview participants until data saturation was reached at 10 interviews, whereby no new codes or themes were identified. All interviews were conducted in the Korean language and audio recorded. The recordings were transcribed verbatim and the transcripts were spot-checked to ensure quality control.

Data analysis

Data were analyzed manually by the first author using thematic analysis, which is considered an apposite method of analysis for seeking to understand experiences, thoughts, or behaviors across a dataset [26, 27]. An initial codebook was developed that includes codes based on prominent features across the entire dataset from the preliminary reading of the transcripts. Transcripts were then coded with multiple codes being allocated where necessary, and emerging codes were added to the codebook (S2 File). Codes were analyzed for patterns and used to identify an emergent thematic framework comprising a hierarchy of meaningful themes and sub-themes of each individual theme. Codes and themes were reviewed by the first author, and names were generated for each theme in English following verification. Salient text passages were extracted to illustrate the emergent themes and were translated into English.

Characteristics of the sample

An overview of the characteristics of the participants is presented in Table 1. We interviewed a total of 10 mothers who were recruited using purposive and snowball sampling strategies. The average age of the mothers was 44.2 years and the majority of the mothers were university graduates. None of the mothers had been previously diagnosed with HPV-related diseases and six mothers had never received an HPV vaccine. Six of the participating mothers had a daughter and the average age of the mothers’ sons was 14.1 years.

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Table 1. Characteristics of the interviewed mothers participating in the study (N = 10).

https://doi.org/10.1371/journal.pone.0282811.t001

Major themes

We identified three major themes: 1) hesitancy towards HPV vaccine for boys due to the absence of gender-neutral HPV vaccination; 2) cultural, social, and familial influences regarding HPV vaccine for boys; and 3) cancer prevention framing increases acceptance of HPV vaccine for boys. These themes and sub-themes are listed in Table 2 are discussed in detail below with illustrative quotations from participants.

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Table 2. Major themes and sub-themes.

https://doi.org/10.1371/journal.pone.0282811.t002

Principal findings

In the present study, we conducted semi-structured one-on-one interviews with a purposive sample of ten mothers of unvaccinated sons living in the capital city of Korea. This qualitative study sought to understand mothers’ current knowledge and beliefs regarding HPV vaccination in males and factors that underlie their hesitancy towards vaccinating boys against HPV. We found that suboptimal levels of HPV and vaccine knowledge among mothers were primarily due to the feminization of HPV and the HPV vaccination policy in Korea that excludes males. Traditionally, the long-standing connection of HPV to cervical cancers has overshadowed the importance of preventing other non-cervical HPV-associated cancers [4]. This disconnect was evident in our study as many of the mothers did not realize their sons’ eligibility for the vaccine due to female-centered discourse around HPV that neglects the risk of associated diseases for both genders. A qualitative study on Korean American parents’ vaccination beliefs also documented this gender bias as the parents believed the vaccine was beneficial only for daughters and were reluctant to learn more about the vaccine since they had only sons [28]. Moreover, the avoidance of the unfamiliar English term “HPV” and the medical jargon in the Korean language has unintentionally misguided lay people to refer to the vaccine as “the cervical cancer vaccine.” This label has instilled an erroneous idea in mothers that it does not apply to their sons. However, despite the existing misalignment of the vaccine with females [4] and current knowledge deficits, mothers’ willingness to vaccinate increased when it was framed as cancer prevention for their sons and their future spouses. This finding reinforces the notion that individuals are more likely to undergo a behavioral change when they have higher perceived susceptibility or when an issue becomes more salient to them [29]. It also demonstrates that composing messages that appeal to protecting children against cancer is key to increasing HPV vaccine acceptance [30]. For example, messages about penile cancer prevention may draw attention from parents of boys and result in increased vaccine acceptability [31]. Focus on perceived relevance is vital when promoting HPV vaccination in males, and cancer protection benefits should be presented for males along with their future partners using pertinent gain-framed messages.

Although HPV is not a gender-specific infection, the absence of publicly funded HPV vaccination for males has engendered negative sentiments in mothers of sons about the safety and high out-of-pocket costs of the vaccine. Mothers assumed that exclusion of male HPV vaccination from the NIP and lack of recommendation by providers might be due to insufficient research behind it, which has been reported as one of the reasons for parental decisions not to vaccinate sons [15, 32, 33]. While being receptive to their daughters’ uptake because female vaccination is routinized and strongly recommended via formal invitation, mothers in this study expressed fear of unknown side effects for boys, especially considering their young age for a vaccine associated with STIs, as reported in a previous study [34]. Similarly, Chinese immigrant parents had ambivalent perceptions and doubted the claimed protection period for the HPV vaccine if immunized when young [35]. It could be that mothers did not want to tolerate unknown risk and vaccinate their sons for an effect needed many years later when their sexual debut has occurred [35]. Mothers were also hesitant about the immense cost to vaccinate their sons against what was perceived as a female disease. However, they were willing to consider the vaccine if it were provided for free or at cheaper prices, which aligns with a previous study conducted in Canada where mothers were moderately willing to get their sons’ HPV vaccine for free, but much less willing to pay the out-of-pocket cost [36]. This sentiment is likely common among financially underprivileged parents [37]. Recent studies in Canada, Ghana, Nigeria, and Sweden have underscored that high cost would be a major barrier to being interested in or receiving STI vaccines and that those that require multiple doses or boosters, such as the HPV vaccine, will have greater financial implications for public acceptance of out-of-pocket costs [37–40]. A Greek study also found that having a low income was associated with lower HPV vaccination acceptance among mothers for their sons, although income did not influence women’s attitudes for themselves and their daughters [41]. Implementation of gender-neutral HPV vaccination is critical to mitigating these challenges, as it can promote routinization of male HPV vaccination and guard against any misinformation thereby alleviating vaccine hesitancy in mothers of boys [42].

We found that sociocultural factors play a substantial role in shaping maternal perceptions of male HPV vaccination and their vaccine decision-making. In Asian cultures, parents tend to be heavily influenced by, or even defer decision-making regarding HPV vaccination to physicians [43]. We observed this cultural attribute in our study. Lack of recommendation from providers and perceived disapproval from the mothers’ most trusted source of health information was a reason for them to be undecided or postpone the vaccine for their sons. Similarly, providers’ recommendations affected HPV vaccination decisions of Korean American parents [28] due to the cultural value of hierarchical authority in which a doctor is viewed as highly esteemed [28]. Given the parents’ adherence to expert medical opinion inherent in Asian culture, public health authorities and health care providers should proactively instill the importance of vaccinating boys against HPV until this information permeates parents’ social networks. Mothers in this study also reported that very few others in their community had heard of the HPV vaccine for boys and believed that other mothers chose not to vaccinate their sons. Other parents’ resistance to HPV vaccination for boys appeared to give more weight to mothers’ decisions against the vaccine that they perceived to carry potential risks. This phenomenon implies that individuals more readily accede to perceptions of others’ vaccination beliefs and practices, known as descriptive social norms [44], when the vaccine of interest is relatively new [45]. Our finding confirms that of previous research on English- and Spanish-speaking parents in the United States that beliefs about other parents’ practices with regard to HPV vaccine for sons are a potentially powerful factor [46]. Parental beliefs that their peers are not vaccinating their sons can develop less interest in vaccinating their sons, driving further skepticism about the HPV vaccine [46]. Such attitudes can also be delineated in terms of social-network theory where non-vaccinators tend to know and associate with other non-vaccinators [47]. Furthermore, the taboo nature of sexual communication in Korea [28], and efforts to conform to such societal norms can explain mothers’ low proclivity to discuss the sexual health of their sons with other mothers. Mothers are likely to postpone or refuse the HPV vaccine for boys due to these cultural values in conjunction with current vaccination norms. To mitigate these issues, community-based interventions that entail a casual environment for vaccination promotion and the correction of misinformation may change parents’ perceptions of the HPV vaccine for boys. For example, public service announcements and webinars in health clinics to raise awareness about male HPV vaccination as well as images of positive parenting to protect their son against HPV on media have been reported as effective methods [28, 48, 49].

Our data indicate that mother-son communication about sexual health let alone prevention of STIs is minimal, which is common in Asian countries where premarital sex is traditionally discouraged [50]. Asian parents tend to approach these issues indirectly or implicitly, avoiding words in their language for sexual health topics, such as HPV [51]. Evidence from the United States suggests that parent-child sexual health communication can curb negative sexual health outcomes [52] and improve HPV vaccination rates [53]. The consistent discomfort mothers felt to initiate conversations with their sons about sexual health may have contributed to their lack of confidence or refusal to talk about HPV vaccination. This could, in part, be explained by the omission of HPV from school-based sexual education, which can misguide mothers to think that it is not necessary for their sons to know about HPV vaccination or to continue the discussion at home. Mothers in this study, most of whom were university graduates, hesitated to vaccinate their sons but also believed that the topic of HPV vaccination should be part of the sex education their sons receive at school. It is interesting to note that contrary to our findings, mothers with a lower level of education in a Greek study were reported to be less likely to accept the HPV vaccine for their children than those with higher education [41]. Researchers from Australia, Sweden, and the United States have recommended that education about HPV should ideally be provided through schooling using age-appropriate, updated resources to emphasize that males have an equal burden of HPV infections [54–56]. This effort may facilitate mother-son sexual health communication at home with a more positive outlook on HPV vaccination for sons.

Strengths and limitations

We conducted the interviews via telephone due to the COVID-19 pandemic, resulting in loss of nonverbal data. However, telephone interviews allowed visual anonymity for the interviewees, who were able to share thoughts more comfortably and give honest responses about this sensitive subject. While none of the mothers had previously been diagnosed with HPV-related disease, which poses a risk of bias, it was entirely unintended as previous diagnosis of HPV was not one of the eligibility criteria. The study excluded parents of partially or fully vaccinated sons, but it is an inherent issue in this context as HPV vaccination for boys is very rare in Korea. Another limitation is the representation of parents through only mothers. However, fathers are less likely to communicate with their adolescents and mothers are typically the parent that communicates sexual health information to their children [57, 58]. Although only ten mothers were interviewed, the same set of questions were asked of all mothers in the purposive sample with a certain degree of participant homogeneity, which led to the collection of rich data and early attainment of thematic saturation; therefore, the sample size was considered appropriate. Strengths of this study include the use of an inductive approach within thematic content analysis that helped generate new insights with detailed accounts of the data. Most importantly, this study has provided in-depth insights into Korean mothers’ perspectives on male HPV vaccination as little qualitative research has previously investigated Asian mothers’ response to vaccinating boys against HPV using their own words.