Non-COVID-19 Vaccine Hesitancy among Migrant Populations Worldwide: A Scoping Review of the Literature, 2000-2020

"Migrants' vaccine-related apprehensions may cascade well beyond their proximate social connections and influence vaccine attitudes and behaviors in their countries-of-origin."

Data suggest that, long after migrant populations have settled in a host country, they continue to experience lower immunisation rates and higher burdens of vaccine-preventable diseases (VPDs) than host populations. Disparities in immunisation among immigrant and refugee populations are surely driven by socio-economic determinants and/or factors such as anticipated stigma, leading to distrust of the host country's health system, but there is growing concern about the understudied phenomenon of anti-vaccine sentiments among migrant populations. Motivated by the belief that monitoring migrants' vaccination-related concerns can inform needed interventions to support vaccine acceptance, these researchers undertook a scoping review of the literature on vaccine hesitancy (VH) in migrant populations. (See their earlier article at Related Summaries, below.)

Eligible articles were published in English or French between 2000 and 2020 and captured multiple dimensions of VH (e.g., vaccine confidence, vaccine refusal, vaccine attitudes, vaccine delay) among migrant populations, defined here as recent immigrants and refugees residing in a given host country, as well as native ethnic minority populations of shared national origin with these immigrants or refugees (e.g., Haitian Americans, Somali-Swedish).

From a total of 8,915 records, the researchers included 112 articles, of which 109 were original quantitative (48%), qualitative (45%), and mixed-methods (7%) research. Notably, only a limited subset of the 112 studies (n = 8; 7%) explicitly focused on VH, as measured by reference to VH in their titles/abstracts and specific investigation of it. Also, the current corpus of evidence on VH in migrant populations is generated almost entirely in high-income countries.

The multilevel model of VH determinants developed by the SAGE Working Group on VH suggests that contextual influences, individual- and group-level factors, and vaccine-specific issues moderate VH. The majority of studies reviewed focused largely on individual-level influences, with roughly half of all articles reviewed exploring knowledge, awareness, attitudes, beliefs, intention, perceptions, and behaviour or practice related to a VPD, its associated vaccine, or to vaccination in general.

Discernable migrant groups with vaccine-specific concerns included Somali diasporas, United Kingdom (UK)-based Poles and Romanians, and United States (US)-based Haitians and Koreans. For example, research covered in the review revealed that, in many Haitian immigrant households, conversations between parents and teenage children about sexually transmitted infection prevention are uncomfortable and may be perceived as a disclosure of or an invitation to sexual activity. Many Haitian parents believe that children should be sexually abstinent, and as such are disinclined toward human papillomavirus (HPV) vaccination. Complacency and suboptimal knowledge are further compounded by lack of physician recommendation, driving low HPV vaccine uptake among unvaccinated college-age Haitian women, who perceive the HPV vaccine as unnecessary unless one has unprotected sex or multiple partners.

Among US-based Latina/Latino immigrants, lower vaccine uptake frequency was mostly associated with awareness levels, knowledge gaps (including misinformed concerns about vaccine harms), and uninsured status. Among immigrants of Asian descent, hesitancy toward the HPV and hepatitis B vaccines is influenced by awareness levels and knowledge gaps, cultural factors, access issues, and lack of physician recommendation.

In reflecting on the findings, the researchers point to contexts of "rising nationalism, widespread anti-immigrant sentiment, and overt xenophobia," which can lead to VH among migrants "as an expression of cultural alienation or even an active skepticism of the healthcare practices of their host's culture..." Thus, the researchers theorise that "the underlying factors of VH may interact through a pathway of social exclusion to moderate VH in some migrant and ethnic minority communities....Hence, efforts to increase vaccine acceptance among immigrants and other members from minoritized groups would be more health-affirming if interventions simultaneously tackle individual-level behavioral variables alongside the broader structural determinants of under-vaccination like racism and xenophobia....A social ecological approach is thus imperative in framing multilevel interventions to address under-immunization and health disparities in migrant communities..."

Among the research gaps and potential areas of investigation presented here are:

• Many studies treat migrant populations as a monolithic group, as reflected in the use of the umbrella term "foreign born" in many US-based observational studies. "Conflating very diverse groups of immigrants into one foreign-born population can be especially problematic when developing targeted interventions to address disparities. Likewise, categorizing all migrants from Latin American countries under the nondescript labels of Latinx or Hispanics may conceal potentially significant subpopulation-level variability, and thus weakening both the validity and utility of many studies, while creating roadblocks in translating evidence into practice when providing care to a large and increasingly diverse immigrant population..."
• The current body of evidence comes almost entirely from a subset of Western-based high-income countries. "Most migrants and refugees, however, reside in countries within the global South..., where evidence of VH has not been investigated sufficiently..."
• In light of the explosion of electronic communication channels, migrants' apprehensions and decision-making about a given vaccine may cascade well beyond their proximate social connections in the host country and may ultimately influence vaccine attitudes and behaviours among social network members in the home country. Reciprocally, migrants' vaccine behaviours may also be influenced by vaccine-related concerns emanating from their native country long into their stays in their newly adopted homelands. Future studies could explore how transnational social networks can be leveraged to increase vaccine acceptance among their various members, given the fact that both migrants and non-migrants engage in exchange of information and misinformation about vaccines.

In conclusion: "Persistent disparities in immunization among immigrant and ethnic minority populations that cannot sufficiently be explained by accessibility[,] and other systemic factors warrant investigation of individual-level variables like VH." This investigation matters because, as the researchers argue, VH and anti-vaccine sentiment precede COVID-19 and will likely persist long after the pandemic is over.