Last data update: Apr 18, 2025. (Total: 49119 publications since 2009)
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Timeliness of childhood vaccinations following strengthening of the second year of life (2YL) immunization platform and introduction of catch-up vaccination policy in Ghana
Muhoza P , Shah MP , Amponsa-Achiano K , Gao H , Quaye P , Opare W , Okae C , Aboyinga PN , Opare JKL , Ehlman DC , Wardle MT , Wallace AS . Vaccines (Basel) 2024 12 (7) 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. |
Beyond misinformation: developing a public health prevention framework for managing information ecosystems
Ishizumi A , Kolis J , Abad N , Prybylski D , Brookmeyer KA , Voegeli C , Wardle C , Chiou H . Lancet Public Health 2024 The COVID-19 pandemic has highlighted how infodemics (defined as an overabundance of information, including misinformation and disinformation) pose a threat to public health and could hinder individuals from making informed health decisions. Although public health authorities and other stakeholders have implemented measures for managing infodemics, existing frameworks for infodemic management have been primarily focused on responding to acute health emergencies rather than integrated in routine service delivery. We review the evidence and propose a framework for infodemic management that encompasses upstream strategies and provides guidance on identifying different interventions, informed by the four levels of prevention in public health: primary, secondary, tertiary, and primordial prevention. On the basis of a narrative review of 54 documents (peer-reviewed and grey literature published from 1961 to 2023), we present examples of interventions that belong to each level of prevention. Adopting this framework requires proactive prevention and response through managing information ecosystems, beyond reacting to misinformation or disinformation. |
Social histories of public health misinformation and infodemics: case studies of four pandemics
Jin SL , Kolis J , Parker J , Proctor DA , Prybylski D , Wardle C , Abad N , Brookmeyer KA , Voegeli C , Chiou H . Lancet Infect Dis 2024 Recognition of misinformation as a public health threat and interest in infodemics, defined as an inundation of information accompanying an epidemic or acute health event, have increased worldwide. However, scientists have no consensus on how to best define and identify misinformation and other essential characteristics of infodemics. We conducted a narrative review of secondary historical sources to examine previous infodemics in relation to four infectious diseases associated with pandemics (ie, smallpox, cholera, 1918 influenza, and HIV) and challenge the assumption that misinformation is a new phenomenon associated with increased use of social media or with the COVID-19 pandemic. On the contrary, we found that the spread of health misinformation has always been a public health challenge that has necessitated innovative solutions from medical and public health communities. We suggest expanding beyond the narrow scope of addressing misinformation to manage information ecosystems, defined as how people consume, produce, interact with, and behave around information, which include factors such as trust, stigma, and scientific literacy. Although misinformation can spread on a global scale, this holistic approach advocates for community-level interventions that improve relationships and trust between medical or public health entities and local populations. |
Predictors for uptake of vaccines offered during the second year of life: Second dose of measles-containing vaccine and meningococcal serogroup A-containing vaccine, Ghana, 2020
Muhoza P , Shah MP , Gao H , Amponsa-Achiano K , Quaye P , Opare W , Okae C , Aboyinga PN , Opare KL , Wardle MT , Wallace AS . Vaccines (Basel) 2023 11 (10) 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. |
A Public Health Research Agenda for Managing Infodemics: Methods and Results of the First WHO Infodemiology Conference.
Calleja N , AbdAllah A , Abad N , Ahmed N , Albarracin D , Altieri E , Anoko JN , Arcos R , Azlan AA , Bayer J , Bechmann A , Bezbaruah S , Briand SC , Brooks I , Bucci LM , Burzo S , Czerniak C , De Domenico M , Dunn AG , Ecker UKH , Espinosa L , Francois C , Gradon K , Gruzd A , Gülgün BS , Haydarov R , Hurley C , Astuti SI , Ishizumi A , Johnson N , Johnson Restrepo D , Kajimoto M , Koyuncu A , Kulkarni S , Lamichhane J , Lewis R , Mahajan A , Mandil A , McAweeney E , Messer M , Moy W , Ndumbi Ngamala P , Nguyen T , Nunn M , Omer SB , Pagliari C , Patel P , Phuong L , Prybylski D , Rashidian A , Rempel E , Rubinelli S , Sacco P , Schneider A , Shu K , Smith M , Sufehmi H , Tangcharoensathien V , Terry R , Thacker N , Trewinnard T , Turner S , Tworek H , Uakkas S , Vraga E , Wardle C , Wasserman H , Wilhelm E , Würz A , Yau B , Zhou L , Purnat TD . JMIR Infodemiology 2021 1 (1) e30979 ![]() ![]() BACKGROUND: An infodemic is an overflow of information of varying quality that surges across digital and physical environments during an acute public health event. It leads to confusion, risk-taking, and behaviors that can harm health and lead to erosion of trust in health authorities and public health responses. Owing to the global scale and high stakes of the health emergency, responding to the infodemic related to the pandemic is particularly urgent. Building on diverse research disciplines and expanding the discipline of infodemiology, more evidence-based interventions are needed to design infodemic management interventions and tools and implement them by health emergency responders. OBJECTIVE: The World Health Organization organized the first global infodemiology conference, entirely online, during June and July 2020, with a follow-up process from August to October 2020, to review current multidisciplinary evidence, interventions, and practices that can be applied to the COVID-19 infodemic response. This resulted in the creation of a public health research agenda for managing infodemics. METHODS: As part of the conference, a structured expert judgment synthesis method was used to formulate a public health research agenda. A total of 110 participants represented diverse scientific disciplines from over 35 countries and global public health implementing partners. The conference used a laddered discussion sprint methodology by rotating participant teams, and a managed follow-up process was used to assemble a research agenda based on the discussion and structured expert feedback. This resulted in a five-workstream frame of the research agenda for infodemic management and 166 suggested research questions. The participants then ranked the questions for feasibility and expected public health impact. The expert consensus was summarized in a public health research agenda that included a list of priority research questions. RESULTS: The public health research agenda for infodemic management has five workstreams: (1) measuring and continuously monitoring the impact of infodemics during health emergencies; (2) detecting signals and understanding the spread and risk of infodemics; (3) responding and deploying interventions that mitigate and protect against infodemics and their harmful effects; (4) evaluating infodemic interventions and strengthening the resilience of individuals and communities to infodemics; and (5) promoting the development, adaptation, and application of interventions and toolkits for infodemic management. Each workstream identifies research questions and highlights 49 high priority research questions. CONCLUSIONS: Public health authorities need to develop, validate, implement, and adapt tools and interventions for managing infodemics in acute public health events in ways that are appropriate for their countries and contexts. Infodemiology provides a scientific foundation to make this possible. This research agenda proposes a structured framework for targeted investment for the scientific community, policy makers, implementing organizations, and other stakeholders to consider. |
Evaluation of container clinics as an urban immunization strategy: Findings from the first year of implementation in Ghana, 2017-2018
Shaum A , Wardle MT , Amponsa-Achiano K , Aborigo R , Opare J , Wallace AS , Bandoh D , Quaye P , Osei-Sarpong F , Abotsi F , Bonsu G , Conklin L . Vaccines (Basel) 2023 11 (4) 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. |
Measuring the burden of infodemics: Summary of the methods and results of the Fifth WHO Infodemic Management Conference
Wilhelm E , Ballalai I , Belanger ME , Benjamin P , Bertrand-Ferrandis C , Bezbaruah S , Briand S , Brooks I , Bruns R , Bucci LM , Calleja N , Chiou H , Devaria A , Dini L , D'Souza H , Dunn AG , Eichstaedt JC , Evers Smaa , Gobat N , Gissler M , Gonzales IC , Gruzd A , Hess S , Ishizumi A , John O , Joshi A , Kaluza B , Khamis N , Kosinska M , Kulkarni S , Lingri D , Ludolph R , Mackey T , Mandić-Rajčević S , Menczer F , Mudaliar V , Murthy S , Nazakat S , Nguyen T , Nilsen J , Pallari E , Pasternak Taschner N , Petelos E , Prinstein MJ , Roozenbeek J , Schneider A , Srinivasan V , Stevanović A , Strahwald B , Syed Abdul S , Varaidzo Machiri S , van der Linden S , Voegeli C , Wardle C , Wegwarth O , White BK , Willie E , Yau B , Purnat TD . JMIR Infodemiology 2023 3 e44207 BACKGROUND: An infodemic is excess information, including false or misleading information, that spreads in digital and physical environments during a public health emergency. The COVID-19 pandemic has been accompanied by an unprecedented global infodemic that has led to confusion about the benefits of medical and public health interventions, with substantial impact on risk-taking and health-seeking behaviors, eroding trust in health authorities and compromising the effectiveness of public health responses and policies. Standardized measures are needed to quantify the harmful impacts of the infodemic in a systematic and methodologically robust manner, as well as harmonizing highly divergent approaches currently explored for this purpose. This can serve as a foundation for a systematic, evidence-based approach to monitoring, identifying, and mitigating future infodemic harms in emergency preparedness and prevention. OBJECTIVE: In this paper, we summarize the Fifth World Health Organization (WHO) Infodemic Management Conference structure, proceedings, outcomes, and proposed actions seeking to identify the interdisciplinary approaches and frameworks needed to enable the measurement of the burden of infodemics. METHODS: An iterative human-centered design (HCD) approach and concept mapping were used to facilitate focused discussions and allow for the generation of actionable outcomes and recommendations. The discussions included 86 participants representing diverse scientific disciplines and health authorities from 28 countries across all WHO regions, along with observers from civil society and global public health-implementing partners. A thematic map capturing the concepts matching the key contributing factors to the public health burden of infodemics was used throughout the conference to frame and contextualize discussions. Five key areas for immediate action were identified. RESULTS: The 5 key areas for the development of metrics to assess the burden of infodemics and associated interventions included (1) developing standardized definitions and ensuring the adoption thereof; (2) improving the map of concepts influencing the burden of infodemics; (3) conducting a review of evidence, tools, and data sources; (4) setting up a technical working group; and (5) addressing immediate priorities for postpandemic recovery and resilience building. The summary report consolidated group input toward a common vocabulary with standardized terms, concepts, study designs, measures, and tools to estimate the burden of infodemics and the effectiveness of infodemic management interventions. CONCLUSIONS: Standardizing measurement is the basis for documenting the burden of infodemics on health systems and population health during emergencies. Investment is needed into the development of practical, affordable, evidence-based, and systematic methods that are legally and ethically balanced for monitoring infodemics; generating diagnostics, infodemic insights, and recommendations; and developing interventions, action-oriented guidance, policies, support options, mechanisms, and tools for infodemic managers and emergency program managers. |
WHO competency framework for health authorities and institutions to manage infodemics: its development and features.
Rubinelli S , Purnat TD , Wihelm E , Traicoff D , Namageyo-Funa A , Thomson A , Wardle C , Lamichhane J , Briand S , Nguyen T . Hum Resour Health 2022 20 (1) 35 BACKGROUND: In April 2020, the World Health Organization (WHO) Information Network for Epidemics produced an agenda for managing the COVID-19 infodemic. "Infodemic" refers to the overabundance of information-including mis- and disinformation. In this agenda it was pointed out the need to create a competency framework for infodemic management (IM). This framework was released by WHO on 20th September 2021. This paper presents the WHO framework for IM by highlighting the different investigative steps behind its development. METHODS: The framework was built through three steps. Step 1 included the preparatory work following the guidelines in the Guide to writing Competency Framework for WHO Academy courses. Step 2 was based on a qualitative study with participants (N = 25), identified worldwide on the basis of their academic background in relevant fields of IM or of their professional experience in IM activities at the institutional level. The interviews were conducted online between December 2020 and January 2021, they were video-recorded and analyzed using thematic analysis. In Step 3, two stakeholder panels were conducted to revise the framework. RESULTS: The competency framework contains four primary domains, each of which comprised main activities, related tasks, and knowledge and skills. It identifies competencies to manage and monitor infodemics, to design, conduct and evaluate appropriate interventions, as well as to strengthen health systems. Its main purpose is to assist institutions in reinforcing their IM capacities and implementing effective IM processes and actions according to their individual contexts and resources. CONCLUSION: The competency framework is not intended to be a regulatory document nor a training curriculum. As a WHO initiative, it serves as a reference tool to be applied according to local priorities and needs within the different countries. This framework can assist institutions in strengthening IM capacity by hiring, staff development, and human resources planning. |
Applying adult learning best practices to design immunization training for health care workers in Ghana
Traicoff D , Tchoualeu DD , Opare J , Wardle M , Quaye P , Sandhu HS , Bonsu G . Glob Health Sci Pract 2021 9 (3) 487-497 INTRODUCTION: A 2016 assessment of frontline health care workers (HCWs) in Ghana identified knowledge, skill, and attitude gaps related to immunization during the second year of life (2YL). The U.S. Centers for Disease Control and Prevention subsequently supported the Ghana Health Service Immunization Program to apply best practices of adult learning and training of trainers (TOT) for a cascade training program for 2YL. METHODS: Five districts from each of the 3 regions (Greater Accra, Northern, and Volta) were selected for the TOT based on key measles and rubella vaccination coverage indicators. The design incorporated best practices of adult learning and TOT. The curriculum integrated 3 major topical themes: technical (immunization topics), operational, and training adults. The technical and operational content was based on HCW tasks most directly affecting 2YL objectives. A cross-functional team developed all classroom, field activity, and training evaluation materials. RESULTS: Seventy-four participants attended TOT workshops in 2017. Based on a rubric defined by the course designers, 99% of the participants reported an acceptable level of confidence to apply and teach the course content. After the TOTs, participants conducted 65 workshops, 43 field visits, and 4 review meetings, reaching 1,378 HCWs within 7 months. Fifty-four percent of HCWs who received training from TOT participants reported an acceptable level of confidence in using the skills, and 92% reported they would prioritize applying the skills acquired during the training. DISCUSSION: The success factors for effective adult learning and TOT can be applied to design and implement high-quality TOT even in resource-limited settings. The factors include using a variety of approaches, spending enough class time to prepare TOT participants for their training role, setting specific expectations for cascading the training, and following up through mentorship and reporting. Strong collaboration across the administrative levels of the Ghana Health Service enabled cascade training. |
Building health workforce capacity for planning and monitoring through the Strengthening Technical Assistance for routine immunization training (START) approach in Uganda
Ward K , Stewart S , Wardle M , Sodha SV , Tanifum P , Ayebazibwe N , Mayanja R , Luzze H , Ehlman DC , Conklin L , Abbruzzese M , Sandhu HS . Vaccine 2019 37 (21) 2821-2830 INTRODUCTION: The Global Vaccine Action Plan identifies workforce capacity building as a key strategy to achieve strong immunization programs. The Strengthening Technical Assistance for Routine Immunization Training (START) approach aimed to utilize practical training methods to build capacity of district and health center staff to implement routine immunization (RI) planning and monitoring activities, as well as build supportive supervision skills of district staff. METHODS: First implemented in Uganda, the START approach was executed by trained external consultants who used existing tools, resources, and experiences to mentor district-level counterparts and, with them, conducted on-the-job training and mentorship of health center staff over several site visits. Implementation was routinely monitored using daily activity reports, pre and post surveys of resources and systems at districts and health centers and interviews with START consultants. RESULTS: From July 2013 through December 2014 three START teams of four consultants per team, worked 6months each across 50 districts in Uganda including the five divisions of Kampala district (45% of all districts). They conducted on-the-job training in 444 selected under-performing health centers, with a median of two visits to each (range 1-7, IQR: 1-3). More than half of these visits were conducted in collaboration with the district immunization officer, providing the opportunity for mentorship of district immunization officers. Changes in staff motivation and awareness of challenges; availability and completion of RI planning and monitoring tools and systems were observed. However, the START consultants felt that potential durability of these changes may be limited by contextual factors, including external accountability, availability of resources, and individual staff attitude. CONCLUSIONS: Mentoring and on-the-job training offer promising alternatives to traditional classroom training and audit-focused supervision for building health workforce capacity. Further evidence regarding comparative effectiveness of these strategies and durability of observed positive change is needed. |
Development of a valid and reliable scale to assess parents' beliefs and attitudes about childhood vaccines and their association with vaccination uptake and delay in Ghana
Wallace AS , Wannemuehler K , Bonsu G , Wardle M , Nyaku M , Amponsah-Achiano K , Dadzie JF , Sarpong FO , Orenstein WA , Rosenberg ES , Omer SB . Vaccine 2019 37 (6) 848-856 BACKGROUND: Parents' attitudes and beliefs in vaccination are important to understand for shaping vaccine acceptance and demand interventions. Little research has focused on developing a validated scale to measure parents' attitudes towards vaccinations in low and middle-income countries; Ghana provided an opportunity develop a caregiver vaccination attitudes scale (CVAS) validated against childhood vaccine compliance. METHODS: We conducted a cluster survey of 373 households with children aged 12-35months of age from Northern Region, Ghana. Caregivers responded to 22 vaccination behavior and belief survey items and provided the child's vaccination status. In exploratory factor analysis (EFA) to assess CVAS content validity, we used parallel analysis to guide the number of factors to extract and principal axis factor analysis for factor extraction. Reliability of the scale was assessed using McDonald's Omega coefficient. Criterion validity of scale and subscales was assessed against receipt of vaccinations by 12months of age and vaccination delay, using number of days undervaccinated. RESULTS: EFA of CVAS responses resulted in removing 11 of 22 survey items due to loadings <0.30 and development of a 5-factor structure with subscales for Vaccine-Preventable Disease (VPD) Awareness, Vaccine Benefits, Past Behavior, Vaccine Efficacy and Safety, and Trust. The 5 factors accounted for 69% of the common variance and omega coefficients were >0.73 for all subscales. Validity analysis indicated that for every unit increase in the parent's scale score, the odds of the child being vaccinated decreased by 0.58 (95% confidence interval [CI]: 0.37, 0.68) and the number of days under-vaccinated increased by 86 (95%CI: 28, 143). The final 3-factor scale included Vaccine Benefits, Past Behavior, and Vaccine Efficacy and Safety. DISCUSSION: The final CVAS included three factors associated with vaccine compliance in Ghana, although several survey items suggested for use in vaccine acceptance scales were dropped. Replicating this study in several country settings will provide additional evidence to assist in refining a tool for use in routine vaccine acceptance and demand surveillance efforts. |
Immunization delivery in the second year of life in Ghana: the need for a multi-faceted approach
Nyaku M , Wardle M , Eng JV , Ametewee L , Bonsu G , Larbi Opare JK , Conklin L . Pan Afr Med J 2017 27 4 Introduction: in 2012, pneumococcal conjugate vaccine (PCV), rotavirus vaccine and a second dose of measles-containing vaccine (MCV2) were introduced into the Expanded Program on Immunization (EPI) in Ghana. According to Ghana's EPI schedule, PCV and rotavirus vaccine are given in the first year of life and MCV2 in the second year of life (2YL) at 18 months. Although coverage with the last doses of PCV and rotavirus vaccine reached almost 90% coverage within four years of introduction, MCV2 coverage did not rise above 70%. The World Health Organization Global Measles and Rubella Strategic Plan established a 2020 milestone to achieve at least 95% coverage with the first and second doses of measles-containing vaccine in each district and nationally. We developed a project to address challenges to delivery of immunizations and other child health services at the 18-month visit and throughout the 2YL. Methods: from March to April 2016, we conducted a cluster survey of households (HHs) with children 24-35 months of age in three regions in Ghana to assess knowledge, attitudes and beliefs among caregivers about immunization during the 2YL and to collect childhood vaccination history data using vaccination cards. Three independent samples were selected from the Northern (NR), Volta (VR), and Greater Accra (GAR) regions. A survey and direct observations were performed a ta representative sample of health facilities (HFs) providing immunization services in the same regions to further characterize barriers to immunization access, utilization and delivery in the 2YL. Results: data on a total of 464 children ages 24-35 months were collected in the HH survey: 211 in NR, 153 in VR, and 100 in GAR (response rate > 99%). First dose of measles-containing vaccine (MCV1) coverage was (NR: 87%, VR: 96%, GAR: 99%); however, MCV2 coverage was lower (NR: 60%, VR: 83%, GAR: 70%). MCV1 to MCV2 dropout was 32% in NR, 14% in VR, and 31% in GAR. Caregiver awareness of immunization against measles was 69% in NR, 75% in VR, and 68% in GAR yet less than half knew the recommended ages for receiving the vaccine, (NR: 4%, VR: 9%, GAR: 44%). Among 160 HFs participating in the survey (>50 in each region), most lacked a defaulter tracing system (NR: 94%,VR: 76%,GAR: 85%). A varying proportion of HCWs correctly indicated how to record a catch-up first dose of MCV administered to an 18-month-old child in the 12-23 month immunization register (NR: 38%, VR: 55%, GAR: 67%) and on the vaccination card (NR: 54%, VR: 53%, GAR: 76%). Although more than half of caregivers would accept text messages, (NR: 57%, VR: 78%, GAR: 96%) including reminders, related to their child's immunizations, < 10% HFs were utilizing this practice. Conclusion: challenges encountered with the establishment of an immunization visit beyond the first year of life included knowledge gaps among caregivers, high dropout rates between MCV1 and MCV2 in all study regions, and a lack of defaulter tracing systems in most healthcare facilities providing childhood immunizations. Targeted strategies that promote behavioral, cultural, and policy changes are needed to strengthen 2YL child health service delivery and improve vaccination coverage. |
Characterization of exposures to nanoscale particles and fibers during solid core drilling of hybrid carbon nanotube advanced composites
Bello D , Wardle BL , Zhang J , Yamamoto N , Santeufemio C , Hallock M , Virji MA . Int J Occup Environ Health 2010 16 (4) 434-50 This work investigated exposures to nanoparticles and nanofibers during solid core drilling of two types of advanced carbon nanotube (CNT)-hybrid composites: (1) reinforced plastic hybrid laminates (alumina fibers and CNT); and (2) graphite-epoxy composites (carbon fibers and CNT). Mutliple real-time instruments were used to characterize the size distribution (5.6 nm to 20 μm), number and mass concentration, particle-bound polyaromatic hydrocarbons (b-PAHs), and surface area of airborne particles at the source and breathing zone. Time-integrated samples included grids for electron microscopy characterization of particle morphology and size resolved (2 nm to 20 μm) samples forthe quantification of metals. Several new important findings herein include generation of airborne clusters of CNTs not seen during saw-cutting of similar composites, fewer nanofibers and respirable fibers released, similarly high exposures to nanoparticles with less dependence on the composite thickness, and ultrafine (< 5 nm) aerosol originating from thermal degradation of the composite material. |
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