Understanding the views of adult migrants around catch-up vaccination for missed routine immunisations to define strategies to improve coverage: A UK in-depth interview study.

Background: The World Health Organization's (WHO) Immunization Agenda 2030 emphasises ensuring equitable access to vaccination across the life course. This includes placing an emphasis on migrant populations who may have missed key childhood vaccines, doses, and boosters due to disrupted healthcare systems and the migration process, or differing vaccination schedules in home countries. Guidelines exist in the UK for offering catch-up vaccinations to adolscent and adult migrants with incomplete or uncertain vaccination status (including MMR, Td-IPV, MenACWY, HPV), but emerging evidence suggests awareness and implementation in primary care is poor. It is unclear whether patient-level barriers to uptake of catch-up vaccinations also exist. We explored experiences and views around catch-up vaccination among adult migrants from a range of backgrounds, to define strategies for improving catch-up vaccination policy and practice.

Methods: In-depth semi-structured interviews were carried out in two phases with adult migrant populations (refugees, asylum seekers, undocumented migrants, those with no recourse to public funds) on views and experiences around vaccination, involving a team of peer researchers from specific migrant communities trained through the study. In Phase 1, we conducted remote interviews with migrants resident in the UK for < 10 years, from diverse backgrounds. In Phase 2, we engaged specifically Congolese and Angolan migrants as part of a community-based participatory study. Topic guides were developed iteratively and piloted. Participants were recruited using purposive, opportunistic and snowball sampling methods. Interviews were conducted in English (interpreters offered), Lingala or French and were audio-recorded, transcribed and analysed using a thematic framework approach in NVivo 12.

Results: 71 participants (39 in Phase 1, 32 in Phase 2) were interviewed (Mean age 43.6 [SD:12.4] years, 69% female, mean 9.5 [SD:7] years in the UK). Aside from COVID-19 vaccines, most participants reported never having been offered vaccinations or asked about their vaccination history since arriving in the UK as adults. Few participants mentioned being offered specific catch-up vaccines (e.g. MMR/Td-IPV) when attending a healthcare facility on arrival in the UK. Vaccines such as flu vaccines, pregnancy-related or pre-travel vaccination were more commonly mentioned. In general, participants were not aware of adult catch-up vaccination but regarded it positively when it was explained. A few participants expressed concerns about side-effects, risks/inconveniences associated with access (e.g. links to immigration authorities, travel costs), preference for natural remedies, and hesitancy to engage in further vaccination campaigns due to the intensity of COVID-19 vaccination campaigns. Trust was a major factor in vaccination decisions, with distinctions noted within and between groups; some held a healthcare professional's recommendation in high regard, while others were less trusting towards the healthcare system because of negative experiences of the NHS and past experiences of discrimination, injustice and marginalisation by wider authorities.

Conclusions: The major barrier to adult catch-up vaccination for missed routine immunisations and doses in migrant communities in the UK is the limited opportunities, recommendations or tailored vaccination information presented to migrants by health services. This could be improved with financial incentives for provision of catch-up vaccination in UK primary care, alongside training of healthcare professionals to support catch-up immunisation and raise awareness of existing guidelines. It will also be essential to address root causes of mistrust around vaccination, where it exists among migrants, by working closely with communities to understand their needs and meaningfully involving migrant populations in co-producing tailored information campaigns and culturally relevant interventions to improve coverage.