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Oral cholera vaccination (OCV) campaigns are increasingly used to prevent cholera outbreaks; however, little is known about their cost-effectiveness in refugee camps. We conducted a cost-effectiveness analysis of a pre-emptive OCV campaign in the Maela refugee camp in Thailand, where outbreaks occurred with an annual incidence rate (IR) of up to 10.7 cases per 1000. Data were collected via health sector records and interviews and household interviews. In the base-case scenario comparing the OCV campaign with no campaign, we estimated the campaign effect on the cholera IR and case fatality rate (CFR: 0.09%) from a static cohort model and calculated incremental cost-effectiveness ratios for the outcomes of death, disability-adjusted life-years (DALYs), and cases averted. In sensitivity analyses, we varied the CFR and IR. The household economic cost of illness was USD 21, and the health sector economic cost of illness was USD 51 per case. The OCV campaign economic cost was USD 289,561, 42% attributable to vaccine costs and 58% to service delivery costs. In our base case, the incremental cost was USD 1.9 million per death averted, USD 1745 per case averted, and USD 69,892 per DALY averted. Sensitivity analyses that increased the CFR to 0.35% or the IR to 10.4 cases per 1000 resulted in a cost per DALY of USD 15,666. The low multi-year average CFR and incidence of the cholera outbreaks in the Maela camp were key factors associated with the high cost per DALY averted. However, the sensitivity analyses indicated higher cost-effectiveness in a setting with a higher CFR or cholera incidence, indicating when to consider campaign use to reduce the outbreak risk.

Background: The integration of maternal and child health services (MCH) with routine immunization is an important global health strategy, particularly in low- and middle-income countries (LMICs). However, evidence is lacking regarding the best practices for service integration and the effect of integration on immunization and linked health service outcomes. Methods: We searched publication databases and gray literature for articles published between 2011 and 2020 that include approaches to integrating MCH services with immunizations during the first two years of life in LMICs. Abstracts and full-text articles were screened for eligibility. For the included articles, data extraction and analysis examined the descriptive characteristics of studies, outcomes, and implementation considerations. Results: Among the 16,578 articles screened, 44 met the criteria for inclusion, representing 34 studies, of which 29 were from Africa. The commonly linked MCH services were family planning (24%), human immunodeficiency virus (HIV) diagnosis or care (21%), and malaria prevention or control (21%). Multiple integration strategies were typically used; the co-location of linked services (65%), the provision of extra services by immunization staff (41%), and/or the provision of extra information by immunization staff (41%) were the most common. In general, integration improved MCH service outcomes (76%) and was either beneficial (55%) or neutral for immunization (35%), with some examples in family planning, malaria, and HIV where integrated services were not beneficial. Important implementation considerations included the careful matching of target populations in service re-design, ensuring support from policy, logistics, and information systems, the provision of adequate training and support of staff to avoid overload, clear client communication regarding service integration, and the need to address community concerns. Conclusions: Integrating MCH services with routine immunization can expand linked services and improve immunization coverage. This study has identified key implementation considerations relevant to both childhood and adult vaccination programs. More research is needed regarding costs and client preferences.

Endorsed by the World Health Assembly in 2012, the Global Vaccine Action Plan 2011-2020 (GVAP) (1) calls on all countries to reach ≥90% national coverage with all vaccines in the country's national immunization schedule by 2020. This report updates previous reports (2,3) and presents global, regional, and national vaccination coverage estimates and trends as of 2017. It also describes the number of infants surviving to age 1 year (surviving infants) who did not receive the third dose of diphtheria and tetanus toxoids and pertussis-containing vaccine (DTP3), a key indicator of immunization program performance (4,5), with a focus on the countries with the highest number of children who did not receive DTP3 in 2017. Based on the World Health Organization (WHO) and United Nations Children's Fund (UNICEF) estimates, global DTP3 coverage increased from 79% in 2007 to 84% in 2010, and has remained stable from 2010 to 2017 (84% to 85%). In 2017, among the 19.9 million children who did not receive DTP3 in the first year of life, 62% (12.4 million) lived in 10 countries. From 2007 to 2017, the number of children who had not received DTP3 decreased in five of these 10 countries and remained stable or increased in the other five. Similar to DTP3 coverage, global coverage with the first measles-containing vaccine dose (MCV1) increased from 80% in 2007 to 84% in 2010, and has remained stable from 2010 to 2017 (84% to 85%). Coverage with the third dose of polio vaccine (Pol3) has remained stable at 84%-85% since 2010. From 2007 to 2017, estimated global coverage with the second MCV dose (MCV2) increased from 33% to 67%, as did coverage with the completed series of rotavirus (2% to 28%), pneumococcal conjugate (PCV) (4% to 44%), rubella (26% to 52%), Haemophilus influenzae type b (Hib) (25% to 72%) and hepatitis B (HepB) (birth dose: 24% to 43%; 3-dose series: 63% to 84%) vaccines. Targeted, context-specific strategies are needed to reach and sustain high vaccination coverage, particularly in countries with the highest number of unvaccinated children.

Vaccines prevent 4–5 million deaths every year, but inequities in vaccine coverage persist among key disadvantaged subpopulations. Under-immunized subpopulations (e.g., migrants, slum residents) may be consistently missed with conventional methods for estimating immunization coverage and assessing vaccination barriers. Adaptive sampling, such as respondent-driven sampling, may offer useful strategies for identifying and collecting data from these subpopulations that are often “hidden” or hard-to-reach. However, use of these adaptive sampling approaches in the field of global immunization has not been systematically documented. We searched PubMed, Scopus, and Embase databases to identify eligible studies published through November 2020 that used an adaptive sampling method to collect immunization-related data. From the eligible studies, we extracted relevant data on their objectives, setting and target population, and sampling methods. We categorized sampling methods and assessed their frequencies. Twenty-three studies met the inclusion criteria out of the 3069 articles screened for eligibility. Peer-driven sampling was the most frequently used adaptive sampling method (57%), followed by geospatial sampling (30%), venue-based sampling (17%), ethnographic mapping (9%), and compact segment sampling (9%). Sixty-one percent of studies were conducted in upper-middle-income or high-income countries. Data on immunization uptake were collected in 65% of studies, and data on knowledge and attitudes about immunizations were collected in 57% of studies. We found limited use of adaptive sampling methods in measuring immunization coverage and understanding determinants of vaccination uptake. The current under-utilization of adaptive sampling approaches leaves much room for improvement in how immunization programs calibrate their strategies to reach “hidden” subpopulations.

Background: Understanding the drivers of coverage for vaccines offered in the second year of life (2YL) is a critical focus area for Ghana’s life course approach to vaccination. This study characterizes the predictors of vaccine receipt for 2YL vaccines—meningococcal serogroup A conjugate vaccine (MACV) and the second dose of measles-containing vaccine (MCV2)—in Ghana. Methods: 1522 children aged 18–35 months were randomly sampled through household surveys in the Greater Accra Region (GAR), Northern Region (NR), and Volta Region (VR). The association between predictors and vaccination status was modeled using logistic regression with backwards elimination procedures. Predictors included child, caregiver, and household characteristics. Results: Coverage was high for infant vaccines (>85%) but lower for 2YL vaccines (ranging from 60.2% for MACV in GAR to 82.8% for MCV2 in VR). Predictors of vaccination status varied by region. Generally, older, first-born children, those living in rural settlements and those who received their recommended infant vaccines by their first birthday were the most likely to have received 2YL vaccines. Uptake was higher among those with older mothers and children whose caregivers were aware of the vaccination schedule. Conclusions: Improving infant immunization uptake through increased community awareness and targeted strategies, such as parental reminders about vaccination visits, may improve 2YL vaccination coverage.

Endorsed by the World Health Assembly in 2020, the Immunization Agenda 2030 strives to reduce morbidity and mortality from vaccine-preventable diseases across the life course (1). This report, which updates previous reports (2), presents global, regional,* and national vaccination coverage estimates and trends as of 2019 and describes the number of surviving infants who did not receive the first dose of diphtheria and tetanus toxoids and pertussis-containing vaccine (DTP1) during the first year of life (i.e., zero-dose children), which serves as a proxy for children with poor access to immunization and other health services. Global estimates of coverage with the third dose of DTP (DTP3), the first dose of measles-containing vaccine (MCV1), and the third dose of polio vaccine (Pol3) ranged from 84% to 86% during 2010-2019. Worldwide, 19.7 million children (15%) were not vaccinated with DTP3 in 2019, 13.8 million (70%) of whom were zero-dose children. During 2010-2019, the number of zero-dose children increased in the African, Americas, and Western Pacific regions. Global coverage with the second MCV dose (MCV2) increased from 42% in 2010 to 71% in 2019. During 2010-2019, global coverage with underused vaccines increased for the completed series of rotavirus vaccine (rota), pneumococcal conjugate vaccine (PCV), rubella-containing vaccine (RCV), Haemophilus influenzae type b vaccine (Hib), hepatitis B vaccine (HepB), and human papillomavirus vaccine (HPV). Achieving universal coverage with all recommended vaccines will require tailored, context-specific strategies to reach communities with substantial proportions of zero-dose and incompletely vaccinated children, particularly those in remote rural, urban poor, and conflict-affected communities (3).Endorsed by the World Health Assembly in 2020, the Immunization Agenda 2030 strives to reduce morbidity and mortality from vaccine-preventable diseases across the life course (1). This report, which updates previous reports (2), presents global, regional,* and national vaccination coverage estimates and trends as of 2019 and describes the number of surviving infants who did not receive the first dose of diphtheria and tetanus toxoids and pertussis-containing vaccine (DTP1) during the first year of life (i.e., zero-dose children), which serves as a proxy for children with poor access to immunization and other health services. Global estimates of coverage with the third dose of DTP (DTP3), the first dose of measles-containing vaccine (MCV1), and the third dose of polio vaccine (Pol3) ranged from 84% to 86% during 2010-2019. Worldwide, 19.7 million children (15%) were not vaccinated with DTP3 in 2019, 13.8 million (70%) of whom were zero-dose children. During 2010-2019, the number of zero-dose children increased in the African, Americas, and Western Pacific regions. Global coverage with the second MCV dose (MCV2) increased from 42% in 2010 to 71% in 2019. During 2010-2019, global coverage with underused vaccines increased for the completed series of rotavirus vaccine (rota), pneumococcal conjugate vaccine (PCV), rubella-containing vaccine (RCV), Haemophilus influenzae type b vaccine (Hib), hepatitis B vaccine (HepB), and human papillomavirus vaccine (HPV). Achieving universal coverage with all recommended vaccines will require tailored, context-specific strategies to reach communities with substantial proportions of zero-dose and incompletely vaccinated children, particularly those in remote rural, urban poor, and conflict-affected communities (3).

Strengthening routine immunization systems to successfully deliver childhood vaccines during the second year of life (2YL) is critical for vaccine-preventable disease control. In Ghana, the 18-month visit provides opportunities to deliver the second dose of the measles–rubella vaccine (MR2) and for healthcare workers to assess for and provide children with any missed vaccine doses. In 2016, the Ghana Health Service (GHS) revised its national immunization policies to include guidelines for catch-up vaccinations. This study assessed the change in the timely receipt of vaccinations per Ghana’s Expanded Program on Immunizations (EPI) schedule, an important indicator of service quality, following the introduction of the catch-up policy and implementation of a multifaceted intervention package. Vaccination coverage was assessed from household surveys conducted in the Greater Accra, Northern, and Volta regions for 392 and 931 children aged 24–35 months with documented immunization history in 2016 and 2020, respectively. Age at receipt of childhood vaccines was compared to the recommended age, as per the EPI schedule. Cumulative days under-vaccinated during the first 24 months of life for each recommended dose were assessed. Multivariable Cox regression was used to assess the associations between child and caregiver characteristics and time to MR2 vaccination. From 2016 to 2020, the proportion of children receiving all recommended doses on schedule generally improved, the duration of under-vaccination was shortened for most doses, and higher coverage rates were achieved at earlier ages for the MR series. More timely infant doses and caregiver awareness of the 2YL visit were positively associated with MR2 vaccination. Fostering a well-supported cadre of vaccinators, building community demand for 2YL vaccination, sustaining service utilization through strengthened defaulter tracking and caregiver-reminder systems, and creating a favorable policy environment that promotes vaccination over the life course are critical to improving the timeliness of childhood vaccinations.

Background: In 2017, the Expanded Programme on Immunization in Ghana opened two container clinics in Accra, which were cargo containers outfitted to deliver immunizations. At each clinic, we assessed performance and clinic acceptance during the first 12 months of implementation. Methods: We employed a descriptive mixed-method design using monthly administrative immunization data, exit interviews with caregivers of children of <5 years (N = 107), focus group discussions (FGDs) with caregivers (n = 6 FGDs) and nurses (n = 2 FGDs), and in-depth interviews (IDIs) with community leaders (n = 3) and health authorities (n = 3). Results: Monthly administrative data showed that administered vaccine doses increased from 94 during the opening month to 376 in the 12th month across both clinics. Each clinic exceeded its target doses for the 12–23 month population (second dose of measles). Almost all (98%) exit interview participants stated that the clinics made it easier to receive child health services compared to previous health service interactions. The accessibility and acceptability of the container clinics were also supported from health worker and community perspectives. Conclusions: Our initial data support container clinics as an acceptable strategy for delivering immunization services in urban populations, at least in the short term. They can be rapidly deployed and designed to serve working mothers in strategic areas.

•Administration of multiple injectable vaccines during a single visit is increasing necessary.•Administering multiple injections may not always be acceptable to caregivers and vaccinators.•9.9% of vaccinators and 35.7% of caregivers expressed concerns regarding multiple injections.•Nevertheless all children surveyed received the required vaccines when vaccines were available. As the World Health Organization (WHO) currently recommends that children be protected against 11 different pathogens, it is becoming increasingly necessary to administer multiple injectable vaccines during a single immunization visit. In this study we assess Gambian healthcare providers’ and infant caregivers’ attitudes and practices related to the administration of multiple injectable vaccines to a child at a single immunization visit before and after the 2015 introduction of inactivated polio vaccine (IPV). IPV introduction increased the number of injectable vaccines recommended for the 4-month immunization visit from two to three in The Gambia. We conducted a cross-sectional questionnaire-based survey before and after the introduction of IPV at 4months of age in a representative sample of all health facilities providing immunizations in The Gambia. Healthcare providers who administer vaccines at the selected health facilities and caregivers who brought infants for their 4month immunization visit were surveyed. Prior to IPV introduction, 9.9% of healthcare providers and 35.7% of infant caregivers expressed concern about a child receiving more than 2 injections in a single visit. Nevertheless, 98.8% and 90.9% of infants received all required vaccinations for the visit before and after IPV introduction, respectively. The only reason why vaccines were not received was vaccine stock-outs. Infant caregivers generally agreed that vaccinators could be trusted to provide accurate information regarding the number of vaccines that a child needed. Healthcare providers and infant caregivers in this resource limited setting accepted an increase in the number of injectable vaccines administered at a single visit even though some expressed concerns about the increase.

•Hard-to-reach populations should not be defined based on vaccination outcome.•A clear definition is needed to assess target population size and interventions.•Hard-to-reach populations should be distinguished from hard-to-vaccinate populations.•The literature poorly defines them without criteria or thresholds for classification.•We propose definitions of hard-to-reach and hard-to-vaccinate populations. Extending the benefits of vaccination to everyone who is eligible requires an understanding of which populations current vaccination efforts have struggled to reach. A clear definition of “hard-to-reach” populations – also known as high-risk or marginalized populations, or reaching the last mile – is essential for estimating the size of target groups, sharing lessons learned based on consistent definitions, and allocating resources appropriately. A literature review was conducted to determine what formal definitions of hard-to-reach populations exist and how they are being used, and to propose definitions to consider for future use. Overall, we found that (1) there is a need to distinguish populations that are hard to reach versus hard to vaccinate, and (2) the existing literature poorly defined these populations and clear criteria or thresholds for classifying them were missing. Based on this review, we propose that hard-to-reach populations be defined as those facing supply-side barriers to vaccination due to geography by distance or terrain, transient or nomadic movement, healthcare provider discrimination, lack of healthcare provider recommendations, inadequate vaccination systems, war and conflict, home births or other home-bound mobility limitations, or legal restrictions. Although multiple mechanisms may apply to the same population, supply-side barriers should be distinguished from demand-side barriers. Hard-to-vaccinate populations are defined as those who are reachable but difficult to vaccinate due to distrust, religious beliefs, lack of awareness of vaccine benefits and recommendations, poverty or low socioeconomic status, lack of time to access available vaccination services, or gender-based discrimination. Further work is needed to better define hard-to-reach populations and delineate them from populations that may be hard to vaccinate due to complex refusal reasons, improve measurement of the size and importance of their impact, and examine interventions related to overcoming barriers for each mechanism. This will enable policy makers, governments, donors, and the vaccine community to better plan interventions and allocate necessary resources to remove existing barriers to vaccination.