The systematic search of the literature concerning the study question, identified 2713 records on databases. After removing 1002 duplicates (870 automatically detected and 132 identified through title review), 1711 records were screened by title and abstract. Of these, 1652 were excluded for not aligning with the research topic; 59 were found eligible for full text. From the eligible studies, 19 met all the inclusion criteria and were analyzed for a quality appraisal (40 were excluded). Figure 1 shows the flow diagram of identified studies, also reporting the reason for exclusion of papers included by title/abstract screening. Overall, 13 studies were considered “high quality,” three studies “medium quality,” and three studies had a “low quality” level.

Of the 19 studies identified, 11 were about vaccine hesitancy, five about vaccine execution, two on access to COVID-19 testing, and one was about access to information on COVID-19. The majority (16) were cross-sectional studies, and three were cohort studies. No studies focused specifically on access to COVID-19 care were identified.

The definitions of migrants or ethnic minorities in the different countries were not homogeneous, thus we will quote the term used by the authors of each article. No studies specifically concerning refugees were found.

The information gathered from the included studies were reported in narrative form and divided according to the main outcomes: “vaccine hesitancy,” “vaccine execution,” “access to COVID-19 information and testing.”

In Table 1 the following data are reported: location and study period, study design, study population, sample size, main outcomes, their measures of effect (in terms of incidence, prevalence, morbidity rates, rate ratios, odds ratios, relative risks, hazard ratios), and study quality (in terms of risk of bias).

To show the distribution of the evidence, the findings of the reviews related to the outcomes “vaccine hesitancy” and “vaccine execution” are illustrated in the harvest plot shown in Fig. 2. Owing to the strong heterogeneity of the three studies on “access to COVID-19 information and testing,” these were not represented in the figure but are reported in the narrative synthesis.

Harvest plot of findings of the review related to the outcomes “vaccine hesitancy” and “vaccine execution.” Number above bar: paper reference number as reported in Table 1. Height of bar: quality of the study. Solid color: statistically significant effect. Hatched color: non statistically significant effect. * Ethno-racial status was defined by combining the criteria of place of birth, nationality, and status of the individual and both parents. **All ethnicity other than white

In the harvest plot, bars represent each measure of association between ethnicity (depicted by different colors) and outcomes (vaccine hesitancy and vaccine execution) as calculated in the included studies. For studies that reported multiple measures of association, multiple bars are shown. The number above each bar corresponds to the study's reference number as reported in Table 1. The bars are placed below either the “increased” or “decreased” boxes according to the direction of the effect. When the effect measure was found to be statistically significant, the bar is colored solid; otherwise, it has a striped pattern. The height of the bar corresponds to the quality of the study.

Of the studies concerning vaccine hesitancy, eight were conducted in the UK, one in France, one in Germany, and one in Israel. Eight concerned the general population, the other three focused on healthcare workers, parents/guardians of children aged 18 months or under, and adults with disability, respectively. Overall, all studies identified reported greater vaccine hesitancy among the target population compared to the general population.

Different tools were used to assess COVID-19 vaccine hesitancy and willingness, which are detailed in Table 2.

Two of the studies concerning the general population used data from a UK population-based longitudinal household survey, “Understanding Society,” based on a clustered-stratified probability sample of UK household with boost samples of key ethnic minorities. The first study (Robertson et al. 2021) showed that belonging to certain ethnic groups was associated with greater vaccine hesitancy compared to White British/Irish group. The highest odds ratios (OR) were seen in the Black or Black British group (OR 13.53, 95% CI 7.57–24.19), followed by the Pakistani or Bangladeshi group (OR 3.96, 95% CI 2.05–7.67). Adjusting for covariates (gender, age, birth country, UK country of residence, education level, shielding) made little differences to these associations (OR 13.42, 95% CI 6.86–26.24 and OR 2.54, 95% CI 1.19–5.44, respectively). The second study (Chaudhuri et al. 2022) found that the Black population was the least willing to take the COVID-19 vaccine (OR 0.004, 95%CI 0.002–0.010) followed by the South Asian group (OR 0.106, 95% IC 0.064–0.176).

Other studies from the UK confirmed these findings. A cross-sectional study conducted in Scotland among 3436 individuals (Williams et al. 2021) explored vaccine hesitancy and its association with sociodemographic factors in a survey at two time points: the first survey was conducted during national lockdown and the second 2 months later when restrictions were eased. Ethnicity had a significant effect on intention to accept a COVID-19 vaccine both in the univariate and multivariate logistic regression analyses: participants of white ethnicity were almost three times as likely to accept the vaccine compared to those from Black, Asian, and Minority Ethnic (BAME) groups (adj coefficient 2.91, 95% CI 1.75–4.81) with a model adjusted for age, education level, household income, and high risk/shielding.

A further study (Allington et al. 2021) from the UK reported a positive correlation between membership of an other-than-white ethnic group and COVID-19 vaccine hesitancy (rs = 0.14), conspiracy suspicions (rs = 0.11) and the use of social media for information about COVID-19 (YouTube rs = 0.19 and WhatsApp rs = 0.20). Ethnicity was uncorrelated with perceived personal risk and trust in the government. Interestingly, there was a weak negative correlation between an other-than-white ethnic group and trust in scientists (rs =  −0.05) and medical professionals (rs =  −0.07). The association between COVID-19 vaccine hesitancy and ethnic minority membership was statistically significant when considering trust but not when considering conspiracy and vaccine attitudes in general.

A study conducted in November 2020 (Bajos et al. 2022), including 85,855 adults living in metropolitan France, focused on people who were certain not to be vaccinated. Those with a migratory background were more reluctant to get vaccinated compared to those born in France without history of migration; persons born in French Overseas Departments and their descendants were the most reluctant (OR 1.66, 95% CI 1.41–1.95), followed by second-generation migrants with parents coming from Africa/Asia (OR 1.36, 95% CI 1.23–1.51), from the EU (OR 1.17 95% CI 1.06–1.28), and first-generation migrants coming from the EU (OR 1.16, 95% CI 1.03–1.31) and from Africa/Asia (OR 1.16, 95% CI 1.04–1.30).

A national cross-sectional study carried out in Israel (Green et al. 2021) conducted an internet survey using a panel of over 100,000 people, of whom 957 completed the questionnaires online. Arab participants were much more likely to say that they would completely refuse the vaccination compared to the Jewish participants (men OR 4.79, 95% CI 2.53–9.06; women OR 3.42, 95% CI 2.17–5.41). These findings were consistent after controlling for age and education differences.

Two studies conducted on the general population after the vaccination campaign had already started showed similar results. The first study (Stead et al. 2021) is a cross-sectional study conducted in early 2021, when most people aged over 80 years had been invited to have a vaccine and invitations were started also for those aged over 70. After controlling for socio demographics, those belonging to the Black/Black British group were the least likely to accept the vaccine (adjusted odds ratio (AOR) 0.25, 95% CI 0.14–0.43) followed by mixed/multiple ethnic groups (AOR 0.39, 95% CI 0.21–0.71) and Asian/Asian British (AOR 0.41, 95% CI 0.28–0.61).

The second is a German study (Aktürk et al. 2021) conducted in February 2021 among patients (N = 420) of a Turkish-speaking family doctor in Munich, with sufficient knowledge of the German or Turkish language; it showed that migratory background significantly affected the vaccine intention both in the univariate analyses (OR 4.438, 95% CI 2.436–8.085) and in the multiple logistic regression model (OR 3.082, 95% CI 1.32–1.195) where authors controlled for age, sex, years of school, previous infection, and scores related to COVID-19 knowledge, attitudes, and behavior.

A further study (Bell et al. 2020) used a multimethod approach combining quantitative and qualitative methods thorough a cross sectional survey and semi-structured interviews. They investigated the view on COVID-19 vaccines of 1252 parents or guardians with children of 18 months or under. It emerged that those that self-reported as Black, Asian, Chinese, Mixed, or Other ethnicity were more likely to reject a COVID-19 vaccine for themselves (OR 2.733, 95%CI 1.27–5.88) and for their children (OR 2.549, 95%CI 1.26–5.16), compared to White participants. The multivariable analysis included age, household income, location, and employment as predictive variables in both models.

Another study (Woolf et al. 2021) focused specifically on a population of multi-ethnic clinical and non-clinical UK healthcare workers (HCWs). After adjustment for socio-demographics, job, trust, perceived COVID-19 risk and psychological factors, ethnicity was significantly associated with vaccine hesitancy for Black Caribbean (AOR 3.37, 95%CI 2.11–5.37), Black African (AOR 2.05, 95%CI 1.49–2.82), Asian Chinese (AOR 1.59, 95%CI 1.15–2.20), and White Other groups (AOR 1.48, 95%CI 1.19–1.84).

Finally, a UK cross-sectional study (Emerson et al. 2021) regarding working-age adults extended the observed association between hesitancy and minority ethnic status to people with disability: when compared to White British with no disabilities, participants belonging to other ethnic groups had higher risk of being hesitant both if they had disabilities (APRR 3.79, 95%CI 2.28–6.30) or not (APRR 2.78, 95%CI 1.94–3.99).

Five studies had vaccination uptake as the main outcome. Overall, the studies pointed out that MEM populations had lower odds of being vaccinated.

Three of the studies were conducted in the UK and considered the OR of uptake of at least the first dose of SARS-CoV2 vaccine. In all these studies, MEM populations had lower vaccination rates, with the lowest rates observed among people of the Black ethnic group. The first study (Perry et al. 2021) was conducted in Wales in April 2021 among all individuals aged 50 years and over. After adjusting for age group, health and social care worker status, care home resident status and shielding status, the odds of being vaccinated were lower for individuals of Black (AOR 0.22, 95%CI 0.21–0.24), Asian (AOR 0.41, 95%CI 0.39–0.43), mixed ethnic background (AOR 0.36, 95%CI 0.34–0.38), or other (AOR 0.24, 95%CI 0.22–0.27) ethnic group compared to the aggregated White ethnic group. The second study (Nafilyan et al. 2021) involved 6,655,672 adults aged 70 years and over who were vaccinated for COVID-19 up until March 15, 2021. The vaccination rates were lower among ethnic minority groups compared to White British ethnicity, and the lowest rates were observed among people of Black African and Black Caribbean ethnic backgrounds. Compared with people of White British ethnicity, the AOR of not being vaccinated for Black African individuals was 5.01 (95% CI 4.86 to 5.16, while the OR was 7.62 (95%CI 7.40–7.84). The last study among those conducted in the UK (Martin et al. 2021) considered the health care workers (HCW) population; HCWs from ethnic minority backgrounds were significantly less likely to be vaccinated than their White colleagues, an effect most marked in those of Black ethnicity (Black OR 0.30, 95% CI 0.26–0.34; South Asian OR 0.67, 95% CI 0.62–0.72 adjusted for age, sex, deprivation, occupation, SARS-CoV-2 serology and PCR results, and the reason given for any COVID-19 related work absences).

One study from Israel (Saban et al. 2021) examined the COVID-19 vaccination rates by neighborhood socioeconomic status and ethnic group. Jewish and Arab populations were compared, defining “Jewish” or “Arab” localities if more than 90% of the population was either of Jewish or Arab ethnic composition, while cities with at least 10% Arab residents were defined as “mixed cities.” Higher rates of COVID-19 vaccination were observed in Jewish and mixed localities, and lower in the Arab population: RR for vaccination uptake between the Jewish and Arab localities was 1.07 and 1.08 for the first and second doses, respectively. The study also analyzed vaccine uptake by age group and ethnicity, since the Arab population is generally younger. Uptake was higher in the Jewish population both for under and over 60 s, for all doses, and the disparity was greater for younger than for older people: 33% difference for first dose under 60 s vs 22% for over 60 s; 37% vs 26% for second dose; 75% vs 49% for third dose.

A further study (Bentivegna et al. 2022) considered migrants living in three informal settlements in Rome: Tiburtina (Tb), Termini (Te), and Collatina (C). According to the Italian government, on September 30, 2021, the vaccination coverage of the Italian population was 79.06%, while in these settlements the average vaccination coverage was significantly lower: 13.3% in Tb, 31.4% in Te, and 35.9% in C. Considering the legal status of migrants, the irregular population had the lowest vaccination coverage (11.1% vs. 18.5% in Tb; 23.1% vs. 35% in Te; 35.7% vs. 36% in C).

Only 3 out of 19 studies did not concern vaccination. One study (Khan et al. 2021) investigated the readability of online COVID-19 information and its accessibility to non-native English speakers. They assessed the availability of other languages and the presence of accompanying graphic information. More than half of the websites were deemed as difficult to read, and only 3.4% and 6.8% provided information easily available in other languages and accompanying graphical information, respectively.

The other two studies focused on access to COVID-19 testing in Italy and Switzerland. The first one (Fabiani et al. 2021) compared the median date of testing positive among Italians and non-Italians nationals. Overall, non-Italian cases were diagnosed on a later date compared with Italian cases. The median date of testing positive was April 14 (IQR March 28–May 8) for non-Italian nationals compared to April 1 (IQR March 20–April 18) for Italian nationals. This difference was particularly evident among non-Italian nationals from low Human Development Index (HDI) countries (median date at diagnosis April 29; IQR April 6–June 22).

The second one (Baggio et al. 2021) compared the underserved (undocumented migrants and homeless persons) with the general population who visited the Geneva University Hospitals (HUG) outpatient COVID-19 testing centers. The main outcome was the time interval between the onset of the first symptoms evocative of COVID-19 and the date of presentation at HUG COVID-19 testing center, as a measure of the access to the screening program. Overall, there was a similar proportion of visits occurring within the first 3 days after symptoms onset in both groups (p = 0.149). There were no significant differences in the average number of COVID-19 symptoms at presentation (p = 0.408) and in the proportion of patients tested during the first month of the program (p = 0.751).