Vaccine-preventable disease and the under-utilization of immunizations in complex humanitarian emergencies

Maintaining Immunizations for Vaccine-Preventable Diseases in a Changing World

Immunization has saved an estimated 154 million lives over the past 50 years since the launch of the Essential (formerly Expanded) Program on Immunization in 1974, representing 6 lives saved every minute, every year, for 50 years. But achieving and maintaining high immunization coverage have required sustained political and public commitment, financial resources, strong partnerships, research and innovation, and communication and advocacy. New and evolving challenges to maintaining high immunization coverage have emerged alongside long-standing stubborn obstacles. We review some of these key challenges to immunization in this dynamic, changing world and summarize some promising solutions. Success in some regions of the world in eliminating polio, measles, and rubella, and reducing morbidity and mortality from other vaccine-preventable diseases, should provide hope that progress can be made in achieving and maintaining high immunization coverage. We cannot afford to do otherwise.

Decision-making for childhood vaccination in crisis settings: a survey of practice & barriers

BACKGROUND

Children, particularly those who have received no routine vaccinations (zero-dose children), are at high risk of vaccine-preventable diseases in humanitarian crisis settings. However, the decision-making processes underlying vaccine intervention design and delivery in such settings are poorly understood. The present study investigated the decision-making practices of organisations involved in childhood vaccination in humanitarian crisis settings globally via an online survey.

METHODS

Individuals involved in the design or delivery of childhood vaccination programmes in humanitarian crisis settings were invited to fill out a self-administered online survey. Respondents were asked about factors influencing intervention design and vaccine delivery; use of technical guidance, specifically the WHO decision-making framework for vaccination in acute humanitarian emergencies (WHO Framework); and practices for reaching zero-dose children.

RESULTS

Fourteen responses were received. Large international organisations and UN agencies were overrepresented in the sample. Technical guidance was considered of high importance when designing vaccine interventions. However, the WHO Framework is not available in relevant languages and has not been well-distributed to local and national actors. Awareness of initiatives to reach zero-dose children was high within our sample, though this may not accurately reflect global awareness. Security and resource availability were key barriers to vaccine delivery and reaching zero-dose children. Problems with vaccine access in our sample pertained primarily to issues with the procurement system rather than vaccine cost.

CONCLUSIONS

The WHO Framework should be provided in more languages, and vaccination actors at local and national level should be engaged to improve its practicality and increase awareness of its aims. In order to reach zero-dose children, vaccines must be made available for use in expanded age groups, which is sometimes not currently feasible within the Gavi/UNICEF procurement system. Clarifying this policy would allow relevant organisations to reach more zero-dose children. Additionally, security is a key barrier impeding vaccine delivery, including for zero-dose children. Safe operational space for humanitarian actors in conflict must be maintained and global conflict resolution mechanisms improved.

Identifying vulnerabilities in essential health services: Analysing the effects of system shocks on childhood vaccination delivery in Lebanon

Shocks effects are under-theorised in the growing literature on health system resilience. Existing work has focused on the effects of single shocks on discrete elements within the health system, typically at national level. Using qualitative system dynamics, we explored how effects of multiple shocks interacted across system levels and combined with existing vulnerabilities to produce effects on essential health services delivery, through the prism of a case study on childhood vaccination in Lebanon. Lebanon has experienced a series of shocks in recent years, including large-scale refugee arrivals from neighbouring Syria, the COVID-19 pandemic and a political-economic crisis. We developed a causal loop diagram (CLD) to explore the effects of each shock individually, and in combination. The CLD was developed and validated using qualitative data from interviews with 38 stakeholders working in Lebanon's vaccination delivery system, in roles ranging from national level policy to facility-level service delivery, conducted between February 2020 and January 2022. We found that each of the shocks had different effects on service demand- and supply-side dynamics. These effects cascaded from national through to local levels. Both Syrian refugee movement and the COVID-19 pandemic primarily exposed vulnerabilities in service demand, mainly through slowly emerging knock-on effects on vaccination uptake behaviour among host communities, and fear of contracting infection in crowded health facilities respectively. The economic crisis exposed wider system vulnerabilities, including demand for vaccination as household income collapsed, and supply-side effects such as reduced clinic time for vaccination, declining workforce retention, and reduced availability of viable vaccine doses, among others. Finally, important pathways of interaction between shocks were identified, particularly affecting the balance between demand for vaccination through publicly supported facilities and private clinics. Future research should incorporate dynamic approaches to identifying within-system vulnerabilities and their potential impacts under different scenarios, as a precursor to improved resilience measurement, system preparedness, and intervention targeting.

The Governance of Childhood Vaccination Services in Crisis Settings: A Scoping Review

The persistence of inadequate vaccination in crisis-affected settings raises concerns about decision making regarding vaccine selection, timing, location, and recipients. This review aims to describe the key features of childhood vaccination intervention design and planning in crisis-affected settings and investigate how the governance of childhood vaccination is defined, understood, and practised. We performed a scoping review of 193 peer-reviewed articles and grey literature on vaccination governance and service design and planning. We focused on 41 crises between 2010 and 2021. Following screening and data extraction, our analysis involved descriptive statistics and applying the governance analysis framework to code text excerpts, employing deductive and inductive approaches. Most documents related to active outbreaks in conflict-affected settings and to the mass delivery of polio, cholera, and measles vaccines. Information on vaccination modalities, target populations, vaccine sources, and funding was limited. We found various interpretations of governance, often implying hierarchical authority and regulation. Analysis of governance arrangements suggests a multi-actor yet fragmented governance structure, with inequitable actor participation, ineffective actor collaboration, and a lack of a shared strategic vision due to competing priorities and accountabilities. Better documentation of vaccination efforts during emergencies, including vaccination decision making, governance, and planning, is needed. We recommend empirical research within decision-making spaces.

Communicable diseases in humanitarian operations and disasters

Military organisations have battled communicable disease for millennia. They have pioneered disease prevention from the Crusades to the World Wars and continue to do so today. Predeployment vaccinations and chemoprophylaxis are effective in preventing communicable disease, as is reliable vector destruction and bite prevention, especially in the era of multidrug resistant organisms. These measures are unlikely to be fully possible in disasters, but reactive vaccination and efforts to reduce exposure to communicable disease should be a priority. Communicable diseases can be challenging to diagnose-the UK Defence Medical Services have become familiar with tools such as multiplex PCR and mass spectrometry. These have the potential to accurately identify organisms and sensitivity patterns in austere environments. Management of communicable diseases depends on accurate diagnosis and has a largely well-established evidence base but can be limited by a lack of resources and skills in an austere setting, therefore telemedicine can assist diagnosis and treatment of infections by projecting specialist skill. Systems such as EpiNATO2 are useful in monitoring diseases and identifying trends in order to establish control measures. Many of these tools and techniques are effective in austere environments and offer learning opportunities for those providing care in similar settings. Further research is ongoing into diagnostic tools as well as remote management.

Strengthening vaccination delivery system resilience in the context of protracted humanitarian crisis: a realist-informed systematic review

BACKGROUND

Childhood vaccination is among the most effective public health interventions available for the prevention of communicable disease, but coverage in many humanitarian settings is sub-optimal. This systematic review critically evaluated peer-review and grey literature evidence on the effectiveness of system-level interventions for improving vaccination coverage in protracted crises, focusing on how they work, and for whom, to better inform preparedness and response for future crises.

METHODS

Realist-informed systematic review of peer-reviewed and grey literature. Keyword-structured searches were performed in MEDLINE, EMBASE and Global Health, CINAHL, the Cochrane Collaboration and WHOLIS, and grey literature searches performed through the websites of UNICEF, the Global Polio Eradication Initiative (GPEI) and Technical Network for Strengthening Immunization Services. Results were independently double-screened for inclusion on title and abstract, and full text. Data were extracted using a pre-developed template, capturing information on the operating contexts in which interventions were implemented, intervention mechanisms, and vaccination-related outcomes. Study quality was assessed using the MMAT tool. Findings were narratively synthesised.

RESULTS

50 studies were included, most describing interventions applied in conflict or near-post conflict settings in sub-Saharan Africa, and complex humanitarian emergencies. Vaccination campaigns were the most commonly addressed adaptive mechanism (n = 17). Almost all campaigns operated using multi-modal approaches combining service delivery through multiple pathways (fixed and roving), health worker recruitment and training and community engagement to address both vaccination supply and demand. Creation of collaterals through service integration showed generally positive evidence of impact on routine vaccination uptake by bringing services closer to target populations and leveraging trust that had already been built with communities. Robust community engagement emerged as a key unifying mechanism for outcome improvement across almost all of the intervention classes, in building awareness and trust among crisis-affected populations. Some potentially transformative mechanisms for strengthening resilience in vaccination delivery were identified, but evidence for these remains limited.

CONCLUSION

A number of interventions to support adaptations to routine immunisation delivery in the face of protracted crisis are identifiable, as are key unifying mechanisms (multi-level community engagement) apparently irrespective of context, but evidence remains piecemeal. Adapting these approaches for local system resilience-building remains a key challenge.

The utilisation of vaccines in humanitarian crises, 2015-2019: A review of practice

BACKGROUND

The risk factors that emerge with the onset and protraction of humanitarian crises leave populations at a heightened risk of excess morbidity and mortality from vaccine-preventable diseases (VPDs). There is currently little clarity on which vaccines are being used in crises throughout the world, and whether vaccination decisions correspond to local disease threats. This review aimed to collect and analyse such information.

METHODS

We reviewed vaccination services from January 2015 to June 2019 across all 25 humanitarian responses that had an activated coordination mechanism during this period. A range of online sources and informants within the humanitarian sector were consulted to compile data on which vaccines were provided in each crisis, and the modality and timing of vaccine provision. The package of vaccination services since the start of each crisis was then compared with local disease burden (baseline + excess due to crisis-emergent risk factors).

RESULTS

The range of vaccines used in humanitarian crises appears limited. When offered, vaccines were primarily delivered through the pre-existing routine schedule, with few supplementary actions taken in recognition of the need for rapidly enhancing population immunity. Vaccine packages mostly did not address the actual range of VPDs that likely accounted for substantial disease risk.

CONCLUSIONS

This review suggests inconsistencies and inequities in vaccine provision to crisis-affected populations. A consistent, standardised and broader approach to vaccine use in crises is needed.

Measles in conflict-affected northern Syria: results from an ongoing outbreak surveillance program

Background

The Syrian conflict has dramatically changed the public health landscape of Syria since its onset in March of 2011. Depleted resources, fractured health systems, and increased security risks have disrupted many routine services, including vaccinations, across several regions in Syria. Improving our understanding of infectious disease transmission in conflict-affected communities is imperative, particularly in the Syrian conflict. We utilize surveillance data from the Early Warning Alert and Response Network (EWARN) database managed by the Assistance Coordination Unit (ACU) to explore trends in the incidence of measles in conflict-affected northern Syria and analyze two consecutive epidemics in 2017 and 2018.

Methods

We conducted a retrospective time-series analysis of the incidence of clinically suspected cases of measles using EWARN data between January 2015 and June 2019. We compared regional and temporal trends to assess differences between geographic areas and across time.

Results

Between January 2015 and June 2019, there were 30,241 clinically suspected cases of measles reported, compared to 3193 cases reported across the whole country in the decade leading up to the conflict. There were 960 regional events that met the measles outbreak threshold and significant differences in the medians of measles incidence across all years (p-value < 0.001) and in each pairwise comparison of years as well as across all geographic regions (p-value < 0.001). Although most governorates faced an elevated burden of cases in every year of the study, the measles epidemics of 2017 and 2018 in the governorates of Ar-Raqqa, Deir-Ez-Zor, and Idlib accounted for over 71% of the total suspected cases over the entire study period.

Conclusions

The 2017 and 2018 measles epidemics were the largest since Syria eliminated the disease in 1999. The regions most affected by these outbreaks were areas of intense conflict and displacement between 2014 and 2018, including districts in Ar-Raqqa, Deir-Ez-Zor, and Idlib. The spread of measles in northern Syria serves as an indicator of low immunization coverage and limited access to care and highlights the Syrian peoples’ vulnerability to infectious diseases and vaccine preventable diseases in the setting of the current conflict.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13031-021-00430-0.

Vaccine bidding, procurement and distribution management practices in mainland China: A nationwide study

OBJECTIVE

To conduct a nationwide evaluation of vaccine bidding, procurement and distribution management for understanding and improving the current situation well in mainland China.

METHODS

An institution survey was carried out to collect information on tendering, procurement, distribution and related issues to vaccines by structured questionnaires administered to 31 provinces in mainland China from April to July 2019.

RESULTS

In 13 (41.9%) of 31 provinces, centralized bidding of National Immunization Program (NIP) vaccines was accomplished, and others conducted independent tendering and purchasing in 2018. For non-NIP vaccines, all provinces implemented unified bidding at the provincial level and over half (18, 58.1%) of them chose provincial public resource trading platforms, but their modes varied over provinces. Then procurement was undertaken by the district-level centers for disease control and prevention (CDC) while they were unable to choose the best option of too many vaccines targeted by the province-level CDC for local populations. The distribution modes of NIP and non-National Immunization Program (non-NIP) vaccines were similar overall in a province but very different over provinces. Main mode was that CDCs at different levels delivered about two thirds (64.5%) of NIP vaccines distribution and more than one third (35.5%) of non-NIP vaccines. Another distribution mode was occupied as fully buying the service from third parties in 3 municipalities. Some provinces mixed both modes, too. The total distribution volume of vaccines was 430.7 million doses in 2018. The top five non-NIP vaccines delivered in 2018 were human rabies vaccine, varicella vaccine, EV71 hand foot mouth disease vaccine, hepatitis B vaccine and influenza vaccine.

CONCLUSION

The vaccine biding, procurement and distribution management varied over provinces in mainland China in 2018, especially for non-NIP vaccines. Specific policies and measures should be developed for different regions to improve the immunization management better.

IMMUNOGENICITY AND IMPACT ON NASOPHARYNGEAL CARRIAGE OF A SINGLE DOSE OF PCV10 GIVEN TO VIETNAMESE CHILDREN AT 18 MONTHS OF AGE

Background

This study investigated the immunogenicity and impact on nasopharyngeal carriage of a single dose of PCV10 given to 18-month-old Vietnamese children. This information is important for countries considering catch-up vaccination during PCV introduction and in the context of vaccination during humanitarian crises.

Methods

Two groups of PCV-naïve children within the Vietnam Pneumococcal Project received PCV10 (n=197) or no PCV (unvaccinated; n=199) at 18 months of age. Blood samples were collected at 18, 19, and 24 months of age, and nasopharyngeal swabs at 18 and 24 months of age. Immunogenicity was assessed by measuring serotype-specific IgG, opsonophagocytosis (OPA) and memory B cells (Bmem). Pneumococci were detected and quantified using real-time PCR and serotyped by microarray.

Findings

At 19 months of age, IgG and OPA responses were higher in the PCV10 group compared with the unvaccinated group for all PCV10 serotypes and cross-reactive serotypes 6A and 19A. This was sustained out to 24 months of age, at which point PCV10-type carriage was 60% lower in the PCV10 group than the unvaccinated group. Bmem levels increased between 18 and 24 months of age in the vaccinated group.

Interpretation

We demonstrate strong protective immune responses in vaccinees following a single dose of PCV10 at 18 months of age, and a potential impact on herd protection through a substantial reduction in vaccine-type carriage. A single dose of PCV10 in the second year of life could be considered as part of catch-up campaigns or in humanitarian crises to protect children at high-risk of pneumococcal disease.

The effect of the ongoing civil strife on key immunisation outcomes in the North West and South West regions of Cameroon

BACKGROUND

Civil strife has long been recognized as a significant barrier in the fight against vaccine preventable diseases in several parts of the world. However, little is known about the impact of the ongoing civil strife on the immunisation system in the Northwest (NW) and Southwest (SW) regions of Cameroon, which erupted in late 2016. In this paper, we assessed the effect of the conflict on key immunisation outcomes in the North West and South West regions of Cameroon.

METHODS

Data were obtained from the standard EPI data reporting tool, the District Vaccine and Data Management Tool (DVDMT), from all the districts in the two regions. Completed forms were then reviewed for accuracy prior to data entry at central level. Summary statistics were used to estimate the variables of interest for each region for the years 2016 (pre-conflict) and 2019 (during conflict).

RESULTS

In the two regions, the security situation has deteriorated in almost all districts, which in turn has disrupted basic healthcare delivery in those areas. A total of 26 facilities were destroyed and 11 healthcare workers killed in both regions. Reported immunisation coverage rates for key antigens including, BCG, DPT-3 and MR, witnessed a dramatic decline between 2016 and 2019, ranging from 22% points decline for BCG in the NW and to 42% points decline for DPT-3 in the SW. Similarly, the proportion of districts with DPT-3 coverage of at least 80% dropped from 75% in 2016 to 11% in 2019 in the NW. In the SW this proportion dropped from 16% in 2016 to 0 % in 2019.

CONCLUSION

Our data demonstrates the marked negative impact of the ongoing civil strife on key immunisation outcomes in the two regions and the country at large. This decline could amplify the risk of vaccine preventable diseases vaccine preventable diseases outbreaks in the two regions. Besides the ongoing actions to contain the crises, effective strategies for reaching children in the conflict zones as well as the internally displaced population are needed. There is also the need to rebuild destroyed facilities as well as to protect health facilities and staff from targeted violence.

Delivering health and nutrition interventions for women and children in different conflict contexts: a framework for decision making on what, when, and how

Existing global guidance for addressing women's and children's health and nutrition in humanitarian crises is not sufficiently contextualised for conflict settings specifically, reflecting the still-limited evidence that is available from such settings. As a preliminary step towards filling this guidance gap, we propose a conflict-specific framework that aims to guide decision makers focused on the health and nutrition of women and children affected by conflict to prioritise interventions that would address the major causes of mortality and morbidity among women and children in their particular settings and that could also be feasibly delivered in those settings. Assessing local needs, identifying relevant interventions from among those already recommended for humanitarian settings or universally, and assessing the contextual feasibility of delivery for each candidate intervention are key steps in the framework. We illustratively apply the proposed decision making framework to show what a framework-guided selection of priority interventions might look like in three hypothetical conflict contexts that differ in terms of levels of insecurity and patterns of population displacement. In doing so, we aim to catalyse further iteration and eventual field-testing of such a decision making framework by local, national, and international organisations and agencies involved in the humanitarian health response for women and children affected by conflict.

Internal displacement; an impediment to the successful implementation of planned measles supplemental activities in Nigeria, a case study of Benue State

BACKGROUND

Measles is a highly infectious disease with great burden and implication on a displaced population with low immunity status. The disease can cause up to 140,000 deaths annually. Internal displacement during supplemental immunization activities often affects optimal reach and coverage of the campaign as people move and implementation and logistic plans are usually disrupted with attendant missed children. This study documented the process of extension of the measles vaccination campaign (MVC) 2018 for five internally displaced persons (IDPs) camps in Benue state, not previously in the microplan, to increase population herd immunity.

METHODS

We obtained population figures and disease surveillance data for five IDPs camps and used it to conduct detailed microplanning to determine the requirement for the conduct of additional days of measles vaccination. Vaccination teams used fixed posts in the camps and temporary posts strategy in designated locations in the host communities.

RESULTS

The estimated total population of the IDPs was 170,000 with MVC target population of 9374 which was not earlier planned for. There was reported measles outbreaks in IDP camps in both Guma and Makurdi Local Government areas (LGAs) during period of displacement. Microplans requirement determined 10,421 bundled measles vaccine, 30 health workers, 5 vehicles and 15 motorcycles. A total of 7679 out of 9374 (81.9%) of the eligible children aged 9-59 months were vaccinated during the 3 days of the campaign.

CONCLUSION

Non-inclusion of plans on internally displaced population in supplemental immunization activities (SIAs) microplans have a potential risk of vaccine preventable diseases (VPDs) outbreak. Future Measles Vaccination campaigns should take cognizance of internal displacement due to insecurity and other humanitarian emergencies.

Pneumococcal conjugate vaccine use during humanitarian crises

Streptococcus pneumoniae is a common human commensal that causes a sizeable part of the overall childhood mortality in low income settings. Populations affected by humanitarian crises are at especially high risk, because a multitude of risk factors that are enhanced during crises increase pneumococcal transmission and disease severity. Pneumococcal conjugate vaccines (PCVs) provide effective protection and have been introduced into the majority of routine childhood immunisation programmes globally, though several barriers have hitherto limited their uptake during humanitarian crises. When PCV coverage cannot be sustained during crises or when PCV has not been part of routine programmes, mass vaccination campaigns offer a quick acting and programmatically feasible bridging solution until services can be restored. However, we currently face a paucity of evidence on which to base the structure of such campaigns. We believe that, now that PCV can be procured at a substantially reduced price through the Humanitarian Mechanism, this lack of information is a remaining hurdle to PCV use in humanitarian crises. Considering the difficulties in conducting research in crises, we propose an evidence generation pathway consisting of primary data collection in combination with mathematical modelling followed by quasi-experimental evaluation of a PCV intervention, which can inform on optimal vaccination strategies that consider age targeting, dosing regimens and impact duration.

(Re-) conceptualising vulnerability as a part of risk in global health emergency response: updating the pressure and release model for global health emergencies

Vulnerability has become a key concept in emergency response research and is being critically discussed across several disciplines. While the concept has been adopted into global health, its conceptualisation and especially its role in the conceptualisation of risk and therefore in risk assessments is still lacking. This paper uses the risk concept pioneered in hazard research that assumes that risk is a function of the interaction between hazard and vulnerability rather than the neo-liberal conceptualisation of vulnerability and vulnerable groups and communities. By seeking to modify the original pressure and release model, the paper unpacks the representation or lack of representation of vulnerability in risk assessments in global health emergency response and discusses what benefits can be gained from making the underlying assumptions about vulnerability, which are present whether vulnerability is sufficiently conceptualised and consciously included or not, explicit. The paper argues that discussions about risk in global health emergencies should be better grounded in a theoretical understanding of the concept of vulnerability and that this theoretical understanding needs to inform risk assessments which implicitly used the concept of vulnerability. By using the hazard research approach to vulnerability, it offers an alternative narrative with new perspectives on the value and limits of vulnerability as a concept and a tool.

Risk factors and risk factor cascades for communicable disease outbreaks in complex humanitarian emergencies: a qualitative systematic review

Background

Communicable diseases are a major concern during complex humanitarian emergencies (CHEs). Descriptions of risk factors for outbreaks are often non-specific and not easily generalisable to similar situations. This review attempts to capture relevant evidence and explore whether it is possible to better generalise the role of risk factors and risk factor cascades these factors may form.

Methods

A systematic search of the key databases and websites was conducted. Search terms included terms for CHEs (United Nations Office for the Coordination of Humanitarian Affairs definition) and terms for communicable diseases. Due to the types of evidence found, a thematic synthesis was conducted.

Results

26 articles met inclusion criteria. Key risk factors include crowded conditions, forced displacement, poor quality shelter, poor water, sanitation and hygiene, lack of healthcare facilities and lack of adequate surveillance. Most identified risk factors do not relate to specific diseases, or are specific to a group of diseases such as diarrhoeal diseases and not to a particular disease within that group. Risk factors are often listed in general terms but are poorly evidenced, not contextualised and not considered with respect to interaction effects in individual publications. The high level of the inter-relatedness of risk factors became evident, demonstrating risk factor cascades that are triggered by individual risk factors or clusters of risk factors.

Conclusions

CHEs pose a significant threat to public health. More rigorous research on the risk of disease outbreaks in CHEs is needed, from a practitioner and from an academic point of view.

Challenges in Estimating Vaccine Coverage in Refugee and Displaced Populations: Results From Household Surveys in Jordan and Lebanon

Ensuring the sustained immunization of displaced persons is a key objective in humanitarian emergencies. Typically, humanitarian actors measure coverage of single vaccines following an immunization campaign; few measure routine coverage of all vaccines. We undertook household surveys of Syrian refugees in Jordan and Lebanon, outside of camps, using a mix of random and respondent-driven sampling, to measure coverage of all vaccinations included in the host country's vaccine schedule. We analyzed the results with a critical eye to data limitations and implications for similar studies. Among households with a child aged 12-23 months, 55.1% of respondents in Jordan and 46.6% in Lebanon were able to produce the child's EPI card. Only 24.5% of Syrian refugee children in Jordan and 12.5% in Lebanon were fully immunized through routine vaccination services (having received from non-campaign sources: measles, polio 1-3, and DPT 1-3 in Jordan and Lebanon, and BCG in Jordan). Respondents in Jordan (33.5%) and Lebanon (40.1%) reported difficulties obtaining child vaccinations. Our estimated immunization rates were lower than expected and raise serious concerns about gaps in vaccine coverage among Syrian refugees. Although our estimates likely under-represent true coverage, given the additional benefit of campaigns (not captured in our surveys), there is a clear need to increase awareness, accessibility, and uptake of immunization services. Current methods to measure vaccine coverage in refugee and displaced populations have limitations. To better understand health needs in such groups, we need research on: validity of recall methods, links between campaigns and routine immunization programs, and improved sampling of hard-to-reach populations.