Abstract

BACKGROUND: Ensuring vaccination coverage reaches established herd immunity thresholds (HIT) is the cornerstone of any vaccination programme. Diverse migrant populations in European countries have been associated with cases of vaccine-preventable diseases (VPD) and outbreaks, yet it is not clear to what extent they are an under-immunised group. METHODS: We did a systematic review and meta-analysis to synthesise peer-reviewed published primary research reporting data on the immune status of migrants in EU/EEA countries, the UK and Switzerland, calculating their pooled immunity coverage for measles, mumps, rubella, and diphtheria using random-effects models. We searched on Web of Science, Embase, Global Health and MEDLINE (January 1st 2000 to June 10th 2022), with no language restrictions. The protocol is registered with PROSPERO (CRD42018103666). FINDINGS: Of 1103 abstracts screened, 62 met eligibility criteria, of which 39 were included in the meta-analysis. The meta-analysis included 75 089 migrants, predominantly from outside Europe. Pooled immunity coverage among migrant populations was well below the recommended HIT for diphtheria (n = 7, 57.4% [95% CI: 43.1-71.7%] I2 = 99% vs HIT 83-86%), measles (n = 21, 83.7% [95% CI: 79.2-88.2] I2 = 99% vs HIT 93-95%), and mumps (n = 8, 67.1% [95% CI: 50.6-83.6] I2 = 99% vs HIT 88-93%), and midway for rubella (n = 29, 85.6% [95% CI: 83.1-88.1%] I2 = 99% vs HIT 83-94%), with high heterogeneity across studies. INTERPRETATION: Migrants in Europe are an under-immunised group for a range of important VPDs, with this study reinforcing the importance of engaging children, adolescents, and adults in 'catch-up' vaccination initiatives on arrival for vaccines, doses, and boosters they may have missed in their home countries. Co-designing strategies to strengthen catch-up vaccination across the life-course in under-immunised groups is an important next step if we are to meet European and global targets for VPD elimination and control and ensure vaccine equity.