Why Parents Say No to Having Their Children Vaccinated against Measles: A Systematic Review of the Social Determinants of Parental Perceptions on MMR Vaccine Hesitancy

"[S]cience-based messaging, particularly if communicated by messengers trusted by parents, such as physicians, has the potential to promote an accurate perception of the safety and efficacy of MMR and other childhood vaccines."

Trust and risk perception issues underlie the hesitancy to measles, mumps, and rubella (MMR) and other childhood vaccines. Globally, ongoing outbreaks of measles point to lower parental vaccine confidence and local pockets of unvaccinated and undervaccinated individuals. The geographic clustering of hesitancy to MMR vaccine in the United States (US) indicates the presence of social drivers that shape parental perceptions and decisions on immunisation. Through a US-focused qualitative systematic review of published literature, the researchers determined major themes regarding parental reasons for MMR vaccine hesitancy, social context of MMR vaccine hesitancy, and trustworthy vaccine information sources. This paper discusses implications for policy and practice and calls for intersectoral collaborations across multiple socioecological levels to address hesitancy to MMR and to other childhood vaccines.

Articles were included in this review (n = 115 articles; 7 databases) if they met criteria such as: being written in English; involving empirical research studies and/or literature reviews; and being published from 2000 to 2022 to capture patterns in vaccine hesitancy and vaccine perspectives, attitudes, and behaviour within the context of the social determinants of health (SDOH) to help explain the resurgence in measles during the post-measles elimination era in the US.

Authors of the articles included in this review mentioned the hesitancy to the MMR vaccine along with the hesitancy to other childhood vaccines. For example, 86 of the 115 articles (75%) identified risk of adverse/hypersensitivity reactions as the most common parental concern to childhood vaccines in general, followed by risk of autism (49 of 115 articles; 43%), general/other safety concerns (54 of 115 articles; 47%), and too many vaccines per clinic visit or concerns toward vaccine schedules (49 of 115 articles; 43%). The social drivers of vaccine hesitancy included primary care/healthcare, education, economy, and government/policy factors. Social factors, such as income and education, exerted a bidirectional influence, which facilitated or hindered vaccine compliance depending on how the social determinant was experienced.

Parents used several sources to obtain vaccine information. Primary care/healthcare providers, such as doctors and school nurses, were the most common source of vaccine information, regardless of whether parents were vaccine compliant or vaccine hesitant. However, vaccine-hesitant parents (52 of 115 articles; 45%) and parents whose vaccine views were not specified by the authors (52 of 115 articles; 45%) still used the internet and social media more frequently compared to vaccine-compliant parents (25 of 115 articles; 22%). ("[T]he lack of information verification and quality control with online sources can exaggerate the risk for adverse events while downplaying the benefits of vaccines.")

In terms of reliability of vaccine information, vaccine-compliant parents, vaccine-hesitant parents, and parents with nonspecified vaccine views ranked primary/healthcare sources as the most reliable source of information. Vaccine-compliant (46 of 115 articles; 40%) and parents with nonspecified views (45 of 115 articles; 39%) rated physician-based vaccine sources higher on trustworthiness as opposed to vaccine-hesitant parents (31 of 115 articles; 27%).

Vaccine hesitancy to MMR and other childhood vaccines was clustered in middle- to high-income areas among mothers with a college-level education or higher who preferred internet/social media narratives over physician-based vaccine information. They had low parental trust, low perceived disease susceptibility, and were skeptical of vaccine safety and benefits. In the context of discussing such clustering, the researchers point to the need to understand the unique social conditions in measles hotspots to determine not only the reasons for hesitancy but also how mothers could become positive vaccine influencers.

Studies included in this review either recommended or cited various approaches to vaccine hesitancy, which the researchers classified as primary care/healthcare providers, public health, and government-level strategies. For example, of the 115 articles, 16 (14%) mentioned primary care/healthcare strategies specific to measles/MMR vaccine hesitancy such as communication training (8 articles), creating positive and trusting parent-physician relationships (7 articles), increasing patient-physician interaction time (4 articles), and training physicians and clinical staff on the latest vaccine safety information (1 article).

Based on the findings of the review, the researchers stress that combating MMR vaccine misinformation and hesitancy requires intersectoral and multifaceted approaches at various socioecological levels to address the social drivers of vaccine behaviour. Suggestions provided in the paper's discussion section include, for example:

• Identifying the root causes of parental hesitancy is imperative to address individual concerns, particularly during physician-based vaccine discussions.
• Healthcare providers can use social media as an educational tool, a vaccine scheduler, an appointment reminder, and an advertisement platform. Layering social media with the traditional radio, TV, and print outlets helps geo-target specific communities needing vaccine resources. Vaccine messages tailored toward particular concerns allow healthcare and public health professionals to connect with parents on questions that are both personal and real for them.
• Applying theories such as the Health Belief Model, the Theory of Planned Behavior, and Protection Motivation Theory in vaccine messaging may help counter deeply-embedded beliefs and misinformation.
• Congruent with social learning, vaccine strategies need to integrate behaviour modeling and the positive influences of family, social support networks, and trustworthy sources to reinforce trust and vaccination intent.
• Articles in this review stressed the value of training physicians on handling difficult conversations with vaccine-hesitant parents. The most commonly emphasised suggestion was enhancing parent-physician trust by listening with empathy in purposeful, open, respectful, empathetic, non-judgmental, and unrushed dialogues on vaccines.
• Articles included in this review called for collaborative efforts between healthcare providers and the community to fight vaccine misinformation. For example, to debunk the belief that toxins in vaccines cause Autism Spectrum Disorder (ASD), clear communication is necessary using different platforms (social media, medical, governmental, and educational - e.g., open conversations with physicians) to curb the spread of misinformation.
• To help build trust, correct misinformation, and mollify fears of autism in multicultural and immigrant communities, studies included in this review recommended: (i) using competent interpreters during clinic visits, (ii) providing ample time with physicians to openly discuss vaccine concerns, (iii) scheduling families routinely with the same physician, (iv) providing vaccine information before clinic visits, (v) using images instead of text narratives, (vi) offering clear vaccine recommendations, and (vii) starting the MMR discussion during the 6-month and 9-month well-child visits to mentally prepare parents on the value of timely vaccinations. Involving community figures, such as imams in Somali migrant communities, to advise public health practitioners on culturally appropriate vaccine initiatives may also be beneficial. Cultural practices, such as the strong oral tradition among Somalis, can be utilised in vaccine efforts to positively influence parental peer networks toward vaccine compliance.
• Other approaches mentioned in this review that could boost vaccine acceptance include the following:
  • Creating reminder tools such as using social media for appointments;
  • Administering educational interventions in clinical settings by handing out vaccine information to patients in the waiting room;
  • Connecting emotionally with parents by having physicians share positive personal vaccine stories, family experiences, and personal narratives that are understandable and memorable;
  • Leveraging visually enhanced education (VEE) techniques such as pictures, storyboards, or videos on vaccine-preventable diseases (VPDs) to educate parents on the serious health complications of VPDs;
  • Using simple, clear, and succinct language, including simple analogies, to convey scientific information;
  • Incorporating relatable and easily understood metaphors in discussing vaccine safety, benefits, and adverse effects;
  • Applying motivational interviewing techniques using the "Plan, Do, Study, Act" (PDSA) or the "corroboration, about me, science, explain" (CASE) methods to understand deeply held reasons for hesitancy or refusal;
  • Using a presumptive tone rather than a participatory tone ("We will do the shots" versus "What do you want to do about the shots?" conveys the provider's confidence in vaccines and establishes vaccines as a routine part of a well-child visit); and
  • Applying evidence-based pain control strategies to reduce fear of injections.
• Articles in this review called for legislative action to reexamine non-medical exemption (NME) policies, particularly in communities at risk for outbreaks.

In terms of future study, the researchers note that, while the family can be an important public health ally in expanding vaccine acceptance, a "glaring gap in the literature is the role of fathers in vaccination decisions. Similarly, the involvement of the whole family unit in curbing vaccine hesitancy has not been adequately researched. Studies in the literature focused primarily on mothers....Moreover, vaccine ideologies and decisions can be transmitted intergenerationally. Grandparents, as informal caregivers, can serve as trusted messengers whose positive personal experiences and stories on vaccine-preventable diseases can help counter misinformation and medical mistrust while also providing multi-generational support to the family."

In conclusion: "Addressing vaccine hesitancy is a collective responsibility. A one-size-fits-all approach is unlikely to be successful. Nurturing partnerships of trust among parents, physicians, and government sectors is crucial in dispelling myths and doubts on the benefits and safety of vaccines....Engaging parents in safe and nonjudgmental discussions is vital in effectively tackling vaccine misinformation and hesitancy. Combining the science of vaccines with an in-depth understanding of parental sentiments could open up conversations among those with lingering concerns. Using messages tailored to specific issues may improve the vaccination rates among traditionally hesitant populations."