Seroprevalence of Antibodies against Measles, Rubella and Varicella among Asylum Seekers Arriving in Lower Saxony, Germany, November 2014-October 2015

The immune status of migrant populations in Europe and implications for vaccine-preventable disease control: a systematic review and meta-analysis

BACKGROUND

Ensuring vaccination coverage reaches established herd immunity thresholds (HITs) is the cornerstone of any vaccination programme. Diverse migrant populations in European countries have been associated with cases of vaccine-preventable diseases (VPDs) and outbreaks, yet it is not clear to what extent they are an under-immunized group.

METHODS

We did a systematic review and meta-analysis to synthesize 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 (1 January 2000 to 10 June 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% confidence interval (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-immunized 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-immunized groups is an important next step if we are to meet European and global targets for VPD elimination and control and ensure vaccine equity.

Risk of vaccine preventable diseases in UK migrants: A serosurvey and concordance analysis

Background

Vaccine preventable diseases (VPDs) such as measles and rubella cause significant morbidity and mortality globally every year. The World Health Organization (WHO), reported vaccine coverage for both measles and rubella to be 71 % in 2019, indicating an immunity gap. Migrants in the EU/EEA may be at high risk of VPDs due to under-immunisation and poor living conditions. However, there are limited data on VPD seroprotection rates amongst migrants living in the United Kingdom (UK).

Methods

We conducted an exploratory cross-sectional serosurvey amongst a sample of adult migrants living in Leicester, UK to: (a) determine seroprotection rates for measles, varicella zoster, and rubella in this group; (b) identify risk factors associated with seronegativity and, (c) understand if self-reported vaccine or diseases history is an effective measure of seroprotection. Participants gave a blood sample and completed a questionnaire asking basic demographic details and vaccine and disease history for the three VPDs. We summarised the data using median and interquartile range (IQR) for non-parametric continuous variables and count and percentage for categorical variables. We used logistic regression to establish predictors of seroprotection against these diseases. We examined the reliability of self-reported vaccination/disease history for prediction of seroprotection through a concordance analysis.

Results

149 migrants were included in the analysis. Seroprotection rates were: varicella zoster 98 %, rubella 92.6 % and measles 89.3 %. Increasing age was associated with seroprotection (OR 1.07 95 % CI 1.01-1.13 for each year increase in age). Migrants from Africa and the Middle East (aOR 15.16 95 % CI 1.31 - 175.06) and South/East Asia and Pacific regions (aOR 15.43 95 %CI 2.38 - 100.00) are significantly more likely to be seroprotected against measles as compared to migrants from Europe and Central Asia. The proportions of migrants unsure about their vaccination and disease history combined were 53.0 % for measles; 57.7 % for rubella; 43.0 % for varicella. There was no agreement between self-reported vaccination/disease history and serostatus.

Conclusion

Our findings suggest lower levels of seroprotection against measles in migrants living in Leicester, UK, with younger migrants and those from Europe and Central Asia more likely to lack seroprotection. A high proportion of surveyed migrants were unaware of their vaccination/disease history and self-reported vaccine/disease was a poor predictor of seroprotection against VPDs which is important for clinical decision-making regarding catch-up vaccination in this population. Our results, although derived from a small sample, suggest that there may be gaps in seroimmunity for certain VPDs in particular migrant populations. These findings should inform future qualitative studies investigating barriers to vaccine uptake in migrants and population-level seroprevalence studies aimed at determining individualised risk profiles based on demographic and migration factors.

Active circulation of varicella zoster virus among different age groups in Sudan

In Sudan, data on varicella infections are lacking and the vaccine is currently not in use. The aim of this study was to investigate previous exposure to varicella zoster virus (VZV) among children and adults from the general population and among health-care workers (HCWs) in Khartoum. Dried blood spot samples collected between 2015 and 2016 from 294 children aged 1‒15 years, 153 adult volunteers and 241 HCWs were investigated for the presence of VZV IgG antibodies using ELISA. The overall seroprevalence of VZV IgG antibodies among the investigated cohorts was 50.4%, ranging between 14.3% in children and 79.3% in HCWs. Seropositivity increased with age among children and HCWs (P ⩽ 0.05). A relatively low seropositivity (64.7%) was observed among young adults and HCWs, suggesting that a high proportion of Sudanese adults remain susceptible. In hospital settings, this result implies a risk of nosocomial infection involving both HCWs and vulnerable patients. The results of this first VZV study in Sudan suggest active virus circulation in different age groups. Especially HCWs at the start of their career might benefit from vaccination, not only to save themselves from herpes zoster and its sequelae, but also to indirectly protect vulnerable patients.

Health status and healthcare trajectory of vulnerable asylum seekers hosted in a French Reception Center

BACKGROUND

Europe lacks studies related to asylum-seekers' health.

METHODS

We described the health status, healthcare and follow-up of men seeking asylum, accommodated in a primary reception center in Paris (CPA). This observational study included volunteer patients presenting for care at the CPA primary care unit (PCU) from January to March 2018. They could be referred to on-site GPs and psychiatrists or to surrounding healthcare facilities. After their asylum application, patients were transferred to other French accommodation centers. PCU healthcare professionals could make referrals for close medical reassessments after transfer.

RESULTS

The 728 included men came mostly from Central Asia or Middle East (65%) and Africa (34%). Seventy percent reported violence during migration. Seventy-five percent (547/728) were referred to on-site GPs, 20% to psychiatrists. During patients' stay at CPA, 67% (144/214) of referrals to surrounding healthcare facilities led to performed consultations. Seven percent of all the included patients (49/728) were referred for frequent communicable infectious diseases screening. Final diagnoses (n = 1108) included 31% infectious diseases and 7% psychiatric disorders. When post-transfer accommodation centers could be reached, 69% (33/48) of the medical referrals had led to a scheduled appointment.

CONCLUSIONS

The healthcare trajectory at CPA could benefit from optimization of infectious and psychiatric screenings, and improved coordination of care and follow-up.

Concordance of self-reported varicella history and serology among adolescent and adult refugee patients at a primary care clinic in Toronto, Canada

BACKGROUND

Previous studies have found higher rates of varicella susceptibility among migrants from tropical regions. This study seeks to estimate the prevalence of varicella susceptibility in a cohort of newly arrived refugees and refugee claimants at a primary care clinic in Toronto and to compare patients' self-reported history of varicella infection with serologic test results.

METHODS

We conducted a retrospective chart review of 1888 refugee patients aged 13 years and older rostered at a specialized primary care clinic in Toronto from December 2011 to October 2017. Basic sociodemographic variables, self-reported varicella history, and varicella serologic results were examined.

RESULTS

Based on serologic testing, 8.5% of individuals were varicella non-immune, with highest rates of varicella susceptibility among adolescents aged 13-19 years (13.5%). All adults over age 60 were varicella immune on serology (n = 56). A positive self-reported history of varicella infection was strongly predictive of varicella immunity on serology (PPV 96.8%; 95% CI: 95.2-97.9). A self-reported history of no prior varicella infection did not correlate reliably with serologic test results (NPV 15.8%; 95% CI: 13.3-18.0). A substantial proportion of patients (34.1%) were unsure of their varicella history.

CONCLUSION

Identification and immunization of varicella susceptible refugee newcomers remains a health care priority. Self-reported history of varicella infection had mixed reliability as a predictor of varicella immunity.

One single-center serological survey on measles, rubella and mumps antibody levels of people in Youyang, China

Although measles, rubella and mumps elimination had achieved great progress in recent years, outbreaks were still reported worldwide. Serological surveillance on the remaining susceptibility in the population is essential to evaluate the preventive policy, estimate the current risk of infection, and predict evolutions in the future. In this study, we aimed to investigate the prevalence of seropositivity of antibodies against measles, rubella and mumps in a population of all ages in Youyang, southwest China. A cross-sectional hospital-based study was conducted among 657 cases who attended to Youyang Hospital from Sep 2018 to Aug 2019. Sero IgG antibodies were measured by ELISA. No difference in the seropositivity of antibodies against measles, rubella and mumps was found between neither urban vs. rural, nor male vs. female. The overall seropositivity of anti-measles, rubella, mumps IgG antibodies was 81.1% (95% CI: 78.0-83.9), 65.9% (95% CI: 62.2-69.4) and 63.2% (95% CI: 59.4-66.8), respectively. The IgG seropositivity varied with age significantly. In this study, the seropositivity of antibodies against measles, rubella and mumps among the participants was insufficient in the population, especially among infants, teenagers and productive women, who were suggested to booster the immunity. To better control and eliminate measles, mumps and rubella-related diseases, nation-wide active laboratory-supported surveillance, outbreak investigation and revaccination for vulnerable population are needed.

Severe chickenpox disease and seroprevalence in Sweden - implications for general vaccination

OBJECTIVES

To describe the current panorama of severe chickenpox disease and seroprevalence in Sweden, as a basis for the approaching decision on universal vaccination.

METHODS

We included patients discharged with an International Classification of Diseases, 10th revision-code for chickenpox (B01.1-9) in eight pediatric and infectious diseases departments in Stockholm and Gothenburg in 2012-2014 and reviewed their medical charts. Further, residual serum samples collected from 16 laboratories across Sweden were analyzed for varicella zoster IgG-antibodies to investigate the age-specific seroprevalences.

RESULTS

In all, 218 children and 46 adults were included in the hospital-based study, 87.2% of children and 63.0% of adults had complications. An underlying condition was not associated with an increased risk for complication. In children dehydration (31.7%), bacterial skin infections (29.8%) and neurological involvement (20.6%) were most frequent complications. Among adult cases, 63 % were born abroad. The seroepidemiological analysis included 957 patient samples. Seroprevalence was 66.7% at 5 years and 91.5% at 12 years. Infants and adolescents/adults were overrepresented among admitted patients compared to seroprevalence data.

CONCLUSIONS

Half of all complications in hospitalized chickenpox cases was seen in previously healthy children, which supports universal childhood vaccination. Adult migrants was a risk group for chickenpox hospitalization. Age-specific seroprevalence was similar to neighboring countries.

Epidemiology of varicella among immigrants and non-immigrants in Quebec, Canada, before and after the introduction of childhood varicella vaccination: a retrospective cohort study

BACKGROUND

Many immigrants are susceptible to varicella on arrival to Canada because of different transmission dynamics in their countries of origin and scarcity of vaccination. Universal childhood vaccination programmes decrease varicella incidence rates through herd immunity, but the accumulating number of susceptible adult immigrants could remain at risk for severe varicella. Our aim was to describe the epidemiology of varicella among immigrants and non-immigrants before and after childhood varicella vaccination.

METHODS

We did a population-based, retrospective cohort study of all varicella cases in Quebec, Canada, diagnosed between 1996 and 2014 in administrative health databases linked to immigration data. Cases of varicella met diagnostic codes in the International Classification of Diseases, Ninth and Tenth Revision Canadian modifications. Cases with a co-occurring zoster diagnostic code and immigrants from Australia, New Zealand, the USA, and western European countries were excluded. Vaccination periods included pre-vaccination (1996-98), private vaccination (1999-2005), and public vaccination (2006-14). Incidence rate and comparative rate ratios were estimated using census data.

FINDINGS

A total of 231 339 varicella cases diagnosed between Jan 1, 1996, and Dec 31, 2014, were linked to 1 115 696 immigrants who arrived between Jan 1, 1980, and Dec 31, 2014. 1444 herpes zoster cases and 1276 immigrants from Australia, western Europe, New Zealand, and the USA were excluded. Among 228 619 varicella cases, 13 315 (5·8%) occurred in immigrants. In pre-vaccination versus public vaccination periods, varicella incidence declined in immigrants by 87% (95% CI 86·6-87·9; 324·3 cases per 100 000 person-years to 40·9 cases per 100 000 person-years) and in non-immigrants by 93% (92·4-92·7; 484 cases per 100 000 person-years to 36 cases per 100 000 person-years). Mean age at diagnosis increased in both groups (15·1 vs 19·4 years in immigrants and 8·4 vs 12·0 years in non-immigrants). In the public vaccination period, immigrants younger than 50 years had higher varicella rates than non-immigrants, with relative risk ranging from 1·53 (95% CI 1·37-1·72) to 4·64 (3·90-5·53) with the highest risk in adolescents and young adults, and people from Latin America and the Caribbean (age-specific incidence rate ratio [aIRR]_I-NI pre-vaccination 2·19 and post-vaccination aIRR_I-NI6·07) and south Asia (aIRR_I-NI pre-vaccination 3·41 and aIRR_I-NI post-vaccination 4·46) and in childbearing women (15-40 years; IRR_I-NI 2·48).

INTERPRETATION

Immigrant adolescents, young adults, and women of childbearing age had higher age-standardised rates of varicella than non-immigrants, with increasing disparities following vaccine introduction. Immigrants younger than 50 years of age would benefit from targeted vaccination upon arrival to host countries.

FUNDING

The Canadian Institutes of Health Research and The Department of Medicine, Jewish General Hospital, Montreal, QC, Canada.

Immunity status against tetanus in young migrants: a seroprevalence study

BACKGROUND AND AIM OF THE WORK

Thanks to the highly effective vaccine, tetanus became sporadic in high-income countries with well-established primary childhood immunization programs, but it is common in low-income countries. The migrants, leaving countries with poor immunization programs or where vaccinations have been interrupted, may represent a new risk group for tetanus in host countries. A seroprevalence study was conducted to estimate the immunological status against tetanus in young migrants without vaccination documentation.

METHODS

After a careful assessment by vaccination services of the Local Health Authority, all migrants recently arrived in Italy were included in the serosurvey. Titers of anti-tetanus toxoid were measured using a commercial ELISA kit. Subjects were stratified by age and by WHO region. Antibody titers <0.10 IU/ml were considered to be seronegative, between 0.10 and 1.00 IU/ml as intermediate protection, and >1.00 IU/ml high protection.

RESULTS

From January 2004 to December 2019, 2,326 blood samples were collected. Mean age was 13.9 years with no differences between WHO regions. The percentage of the subjects without protective antibodies was 22.3%, with an intermediate level was 45.2%, with high titer was 32.5%. Among migrant coming from African and Eastern Mediterranean WHO regions, the highest percentages of seronegative titers and, at the same time, the low percentages of high protective levels were found. Titers decreased with age.

CONCLUSIONS

The significant proportion of seronegative migrants and the decrease of protective titers increasing age, confirm the importance of the evaluation of the immunological status to employ the appropriate vaccination strategy.

Measles and rubella seroimmunity in newly arrived adult immigrants in Sweden

BACKGROUND

International migrants could be considered as a risk group for being susceptible to vaccine preventable diseases such as measles and rubella. However, data on immunity in different migrant groups are scarce. Apart from asylum seekers and refugees, other immigrant groups might also be at risk. We have examined measles and rubella specific IgG antibodies among newly arrived adult immigrants in Skåne region in southern Sweden. In contrast to children, adult immigrants are not offered catch-up vaccinations after arrival.

METHODS

Stored serum samples from 989 asylum seekers and 984 pregnant women from the antenatal screening program, who had recently settled in Sweden, were analyzed for specific measles and rubella IgG-antibodies. Sex, age, reason for screening and geographic origin were variables entered into a multivariate regression model.

RESULTS

There were considerable differences in seroimmunity to measles with regard to geographic origin (44-97%). Measles seroimmunity gaps were most prominent in immigrants from some European regions such as the Baltic countries, the former Yugoslavia and the Newly Independent States and Russia. Seroprotection for rubella varied less between geographic regions (90-99%).

CONCLUSION

Susceptibility to measles among adult immigrants arriving in Sweden varies considerably depending on their geographic origin. Vaccinations against measles and rubella should be offered to groups of immigrants who might be incompletely immunized.

Interventions to Improve Vaccination Uptake and Cost Effectiveness of Vaccination Strategies in Newly Arrived Migrants in the EU/EEA: A Systematic Review

Newly arrived migrants to the EU/EEA (arrival within the past five years), as well as other migrant groups in the region, might be under-immunised and lack documentation of previous vaccinations, putting them at increased risk of vaccine-preventable diseases circulating in Europe. We therefore performed a systematic review conforming to PRISMA guidelines (PROSPERO CRD42016045798) to explore: (i) interventions that improve vaccine uptake among migrants; and (ii) cost-effectiveness of vaccination strategies among this population. We searched MEDLINE, Embase, CINAHL, and Cochrane Database of Systematic Reviews (CDSR) between 1 January 2006 to 18 June 2018. We included three primary intervention studies performed in the EU/EEA or high-income countries and one cost effectiveness study relevant to vaccinations in migrants. Intervention studies showed small but promising impact only on vaccine uptake with social mobilization/community outreach, planned vaccination programs and education campaigns. Targeting migrants for catch-up vaccination is cost effective for presumptive vaccination for diphtheria, tetanus, and polio, and there was no evidence of benefit of carrying out pre-vaccination serological testing. The cost-effectiveness is sensitive to the seroprevalence and adherence to vaccinations of the migrant. We conclude that scarce but direct EU/EEA data suggest social mobilization, vaccine programs, and education campaigns are promising strategies for migrants, but more research is needed. Research should also study cost effectiveness of strategies. Vaccination of migrants should continue to be a public heath priority in EU/EEA.

An outbreak of chickenpox in an asylum seeker centre in Italy: outbreak investigation and validity of reported chickenpox history, December 2015-May 2016

An outbreak of chickenpox occurred between December 2015 and May 2016 among asylum seekers in a reception centre in Latium, Italy. We describe the epidemiological and laboratory investigations, control measures and validity of reported history of chickenpox infection. Serological screening of all residents and incoming asylum seekers was performed, followed by vaccine offer to all susceptible individuals without contraindication. Forty-six cases were found and 41 were associated with the outbreak. No complications, hospitalisations or deaths occurred. Serological testing was performed in 1,278 individuals and 169 were found to be susceptible, with a seroprevalence of 86.8%. A questionnaire was administered to 336 individuals consecutively attending the CARA health post to collect their serological result. The sensitivity, specificity and the positive and negative predictive value (PPV and NPV) of the reported history of chickenpox were 45.0%, 76.1%, 88.3% and 25.6%, respectively. We observed an increasing trend for the PPV and decreasing trend for the NPV with increasing age. Our report confirms that, in the asylum seeker population, chickenpox history is not the optimal method to identify susceptible individuals. Our experience supports the need for additional prevention and control measures and highlights the importance of national and local surveillance systems for reception centres.

Immunity against measles, mumps, rubella, varicella, diphtheria, tetanus, polio, hepatitis A and hepatitis B among adult asylum seekers in the Netherlands, 2016

Asylum seekers are a vulnerable population for contracting infectious diseases. Outbreaks occur among children and adults. In the Netherlands, asylum seeker children are offered vaccination according to the National Immunization Program. Little is known about protection against vaccine-preventable diseases (VPD) in adult asylum seekers. In this 2016 study, we assessed the immunity of adult asylum seekers against nine VPD to identify groups that might benefit from additional vaccinations. We invited asylum seekers from Syria, Iran, Iraq, Afghanistan, Eritrea and Ethiopia to participate in a serosurvey. Participants provided informed consent and a blood sample, and completed a questionnaire. We measured prevalence of protective antibodies to measles, mumps, rubella, varicella, diphtheria, tetanus, polio type 1-3 and hepatitis A and B, stratified them by country of origin and age groups. The median age of the 622 participants was 28 years (interquartile range: 23-35), 81% were male and 48% originated from Syria. Overall, seroprotection was 88% for measles (range between countries: 83-93%), 91% for mumps (81-95%), 94% for rubella (84-98%), 96% for varicella (92-98%), 82% for diphtheria (65-88%), 98% for tetanus (86-100%), 91% (88-94%) for polio type 1, 95% (90-98%) for polio type 2, 82% (76-86%) for polio type 3, 84% (54-100%) for hepatitis A and 27% for hepatitis B (anti-HBs; 8-42%). Our results indicate insufficient protection against certain VPD in some subgroups. For all countries except Eritrea, measles seroprotection was below the 95% threshold required for elimination. Measles seroprevalence was lowest among adults younger than 25 years. In comparison, seroprevalence in the Dutch general population was 96% in 2006/07. The results of this study can help prioritizing vaccination of susceptible subgroups of adult asylum seekers, in general and in outbreak situations.

Refugee Health: An Ongoing Commitment and Challenge

Refugees represent a diverse group of displaced individuals with unique health issues and disease risks. The obstacles facing this population have their origins in war, violence, oppression, exploitation, and fear of persecution. Regardless of country of origin, a common bond exists, with refugees often confronting inadequate healthcare resources, xenophobia, discrimination, and a complex web of legal barriers in their new homelands. In many cases, the plight of refugees is multigenerational, manifesting as mental health issues, abuse, poverty, and family disruption. The health trajectory of refugees remains an ongoing commitment and challenge.

Measles, Rubella and Varicella IgG Seroprevalence in a Large Refugee Cohort in Germany in 2015: A Cross-Sectional Study

INTRODUCTION

The current extent of migration to the European continent is associated with exceptional humanitarian challenges. In 2015, Western Europe faced an enormous immigration of refugees with largely unknown protection status against communicable diseases. To adapt vaccination strategies, we aimed at assessing seroprevalences against three of the most relevant vaccine preventable diseases (VPD) in a large representative cohort.

METHODS

IgG seroprevalences for rubella, varicella (n = 554) and measles (n = 552) were analyzed in inhabitants of a Northern German refugee camp in the summer of 2015.

RESULTS

Of the refugees, 77.9% were male (mean age 27.4 years for male and 26.8 years for female migrants). Most refugees came from the Eastern Mediterranean region (83.4%), followed by immigrants from Eastern Europe (7.4%), Africa (4.6%), or other regions (4.5%). The vast majority of migrants were protected against the three VPD: overall IgG seropositivity was 88.5% for measles, 77.9% for rubella and 95.9% for varicella. However, seroprevalences showed age- and origin-dependent differences. Varicella immunity, for example, was lowest in the youngest age group of both genders (10.1% of male/4.5% of female seronegative refugees <18 years vs. 100% seropositivity in men and women >49 years of age), and Sudanese migrants displayed particularly low rates of protection against varicella.

CONCLUSION

In accordance with previous studies, our analyses show an overall satisfactory seropositivity against measles, rubella, and varicella in refugees entering Europe during the current exodus. However, this rate is not sufficient for preventing transmission. For example, the rate of 12.9-17.9% female refugees at reproductive age unprotected against measles and the low protection levels against varicella in minors observed in our cohort emphasizes the need for stringent vaccination strategies in refugees coming to Europe during the current crisis.