Comparisons in the Health and Economic Assessments of Using Quadrivalent Versus Trivalent Influenza Vaccines: A Systematic Literature Review

ObjectivesSeasonal influenza vaccines protect against 3 (trivalent influenza vaccine [IIV3]) or 4 (quadrivalent influenza vaccine [IIV4]) viruses. IIV4 costs more than IIV3, and there is a trade-off between incremental cost and protection. This is especially the case in low- and middle-income countries (LMICs) with limited budgets; previous reviews have not identified studies of IIV4-IIV3 comparisons in LMICs. We summarized the literature that compared health and economic outcomes of IIV4 and IIV3, focused on LMICs.MethodsWe systematically searched 5 databases for articles published before October 6, 2021, that modeled health or economic effects of IIV4 versus IIV3. We abstracted data and compared findings among countries and models.ResultsThirty-eight studies fit our selection criteria; 10 included LMICs. Most studies (N = 31) reported that IIV4 was cost-saving or cost-effective compared with IIV3; we observed no difference in health or economic outcomes between LMICs and other countries. Based on cost differences of influenza vaccines, only one study compared coverage of IIV3 with IIV4 and reported that the maximum IIV4 price that would still yield greater public health impact than IIV3 was 13% to 22% higher than IIV3.ConclusionsWhen vaccination coverage with IIV4 and IIV3 is the same, IIV4 tends to be not only more effective but more cost-effective than IIV3, even with relatively high price differences between vaccine types. Alternatively, where funding is limited as in most LMICs, higher vaccine coverage can be achieved with IIV3 than IIV4, which could result in more favorable health and economic outcomes.     

Validity of maternal recall for estimating childhood vaccination coverage – Evidence from Nigeria

BackgroundVaccination coverage surveys in low- and middle-income countries typically estimate vaccination coverage using data from vaccination cards, parental recall, or a combination of the two. However, these surveys are often complicated by the pervasive absence of vaccination cards, forcing researchers to rely on parental recall. We assessed the validity of mothers’ recall against home-based vaccination cards using data from a community-based household survey in Nigeria.MethodsA cross-sectional survey of 1,254 mothers of children aged 12–23 months was performed in Enugu State, Nigeria in July 2020. Data on vaccination status for BCG, OPV, DPT, Measles, Yellow fever, and Vitamin A supplement were collected using two data sources: home-based vaccination cards and mothers’ recall. We evaluated the level of agreement between the two data sources; estimated the sensitivity and specificity of mothers’ recalls; and computed multivariable regression models to identify socio-demographic factors associated with mothers’ recall bias.ResultsOut of 1,254 mothers interviewed, 578 (46.1%) mothers with vaccination cards were included in this analysis. Vaccination coverage levels were generally similar across data sources, though recall-based data generally underestimated the coverage. The level of agreement between the two data sources was high (≥91.0% for all vaccine types) with recall bias due to under-reporting generally higher than recall bias due to over-reporting. The sensitivity of parental recalls was high for all vaccine types, while the specificity was low across vaccine types. Across all vaccines, mothers recall bias was significantly associated with the rural residence and not receiving postnatal care.ConclusionIn the absence of vaccination cards, mothers’ recall of their children’ vaccination status for BCG, OPV, DPT, Measles, Yellow fever and Vitamin A is a valid instrument for estimating childhood vaccination coverage in this setting in Nigeria. However, additional research is needed to confirm these findings at higher sub-national and national levels.     

Reasons for non-vaccination and incomplete vaccinations among children in Pakistan

BackgroundGlobal immunization efforts have received a boost through the introduction of several new vaccines. These efforts however, are threatened by sub-optimal vaccine coverage, particularly in countries with large birth cohorts. Pakistan has one of the largest birth cohorts in the world, where coverage of routine vaccination remains persistently inadequate. We undertook this study to ascertain reasons for non-vaccination or incomplete vaccination of children less than two years in 8 districts of southern Pakistan.MethodsA cross-sectional survey using WHO recommended rapid coverage assessment technique was conducted in 2014. Using probability proportional to size method, we sampled 8400 households with eligible children (aged 4–12 months). Using a structured questionnaire, mothers or other primary caregivers were interviewed to determine vaccination status of an index child. In case of non-vaccination or incomplete vaccination, respondents were asked for reasons leading to low/no vaccine uptake.ResultsBased on both vaccination record and recall, only 30.8% of children were fully vaccinated, 46% had an incomplete vaccination status while 23%were non-vaccinated. The most frequently reported reasons for non-vaccination included: mothers/caregivers being unaware of the need for vaccination (35.3%), a fear of side effects (23%), mother/caregiver being too busy (16.6%), distance from vaccination centers (13.8%), and non-availability of either vaccinators or vaccines at vaccination centers (10.7%). Reasons identified for incomplete vaccination were similar, with caregivers being unaware of the need for subsequent doses (27.3%), non-availability of vaccinators or vaccines (17.7%), mother/caregiver being too busy (14.8%), fear of side effects (11.2%), and postponement for another time (8.7%).ConclusionVarious factors result in non-compliance with vaccination schedules and vaccine refusal within the surveyed communities, ranging from lack of knowledge to non-availability of supplies at vaccination centers. These barriers are best addressed through multi-pronged strategies addressing supply gaps, increasing community awareness and enhancing demand for routine vaccination services.     

Interventions to increase influenza vaccination rates in children with high-risk conditions—A systematic review

BackgroundInfluenza is a common cause of morbidity and mortality, especially among the elderly and those with certain chronic diseases. Annual influenza vaccination is recommended for individuals in at-risk groups, but rates of vaccination are particularly low in children with high-risk conditions (HRCs).ObjectiveTo conduct a systematic review of studies that have examined interventions aimed at improving influenza vaccination in children with HRCs.MethodsTwo databases – PubMed and SCOPUS – were searched (with no time or language restrictions) using a combination of keywords – Influenza AND vaccination OR immunization OR children AND asthma OR malignancy OR high-risk AND reminder. Duplicates were removed, and abstracts of relevant articles were screened using specific inclusion/exclusion criteria. Thirteen articles were selected, and five additional studies were identified following a review of the reference lists of the initial thirteen articles, bringing the total number to eighteen.ResultsMost studies were conducted in the United States. Among the 18 studies, there was one systematic review of a specific intervention in asthmatic children, seven randomized controlled trials (RCTs), six before-and-after studies, one non-randomized controlled trial, one retrospective cohort study, one quasi-experimental post-test study, and one letter to editors. Interventions reported include multi-component strategies, letter reminders, telephone recall, letters plus telephone calls, an asthma education tool and year-round scheduling for influenza vaccination, amongst others.ConclusionThere is good evidence that reminder letters will improve influenza vaccination uptake in children with HRCs, but the evidence that telephone recall or a combination of letter reminder and telephone recall will improve uptake is weak. It is not known if multiple reminder letters are more effective than single letters or if multi-component strategies are more effective than single or dual component strategies. There is a need for further research of these interventions, possibly outside the United States.     

The impact of time since vaccination and study design on validity in parental recall of childhood vaccination status in the All Our Families cohort

IntroductionParental reporting of childhood vaccination status is often used for policy and program evaluation and research purposes. Many factors can bias parental reporting of childhood vaccination status, however, to our knowledge, no analysis has assessed whether time since vaccination impacts reporting accuracy. Therefore, using the Calgary electronic vaccine registry (PHANTIM) as the gold standard, we aimed to test the accuracy of parental reporting of childhood vaccination status at three different time-points since vaccination.MethodsThe All Our Families (AOF) cohort study asked parents to report their child’s 2, 4, 6, 12 and 18 month vaccines (vaccination time-point) on questionnaires given when the child was 1, 2 and 3 years of age (survey time-point). We linked the AOF parental reporting of vaccination status to the PHANTIM registry and calculated the percent agreement and difference in coverage estimates between PHANTIM and AOF at each vaccination and survey time-point combination. Furthermore, we measured the sensitivity and specificity, and negative (NPV) and positive predictive values (PPV) of parental vaccine recall across time.ResultsAOF parent reports of coverage rates were consistently higher than the PHANTIM estimates. While we saw significant differences in percent agreement for certain vaccination time-points, we saw no consistent directional difference by survey time-point, suggesting that parental accuracy did not change with time. We found a uniformly high sensitivity across all vaccination and survey time-points, and no consistent patterns in the specificity, PPV and NPV results.ConclusionTime since vaccination may not be the most important consideration when designing and implementing a vaccination survey. Other factors that may contribute to the bias associated with parental reporting of vaccination status include the complexity of the vaccine schedule, schedule changes over time, and the wording and structure of the questionnaires.     

Socioeconomic characteristics associated with the introduction of new vaccines and full childhood vaccination in Ghana, 2014

BackgroundChildhood vaccination in Ghana has historically been high, but the impact of recently introduced vaccines on coverage is unknown. We calculate vaccine coverage of Ghanaian children– contrasting newly introduced vaccines and those long available – and describe associations between sociodemographic indicators and full vaccination.MethodsData from the 2014 Ghana Demographic and Health Survey was used to calculate full vaccination, defined as receipt of one dose bacillus Calmette-Guérin (BCG); two doses of rotavirus vaccine; 3 doses of pentavalent vaccine, oral polio vaccine (OPV), and pneumococcal conjugate vaccine (PCV); and one dose of measles-rubella vaccine and yellow fever vaccine, among children age 12–24 months. Logistic regression with survey procedures was used to estimate odds ratios for socioeconomic factors’ association with full vaccination.ResultsThe sample comprised a total of 1107 children 12–24 months. Full vaccination coverage was 70.8%. Vaccination coverage was higher for vaccines administered at younger ages (e.g., birth dose of BCG was 97.0%) than at older ages (e.g., yellow fever at 9 months was 88.2%). Newly introduced vaccines had lower coverage: at 10 weeks, pentavalent 2 was 95.4%, versus 91.2% for PCV 2 and 88.8% for rotavirus 2. Living outside of Greater Accra, home delivery, younger maternal age, urban residence, and more than one child under five in the home were all associated with decreased odds of full vaccination in the adjusted analysis whereas sex of the child, wealth, religion, and maternal education were not associated with full vaccination status.ConclusionGhana has high overall vaccination rates although disparities in full vaccination by sociodemographic status exist. As vaccine recommendations are revised, it will be important to insure equitable access to vaccination for all children regardless of demographic and socioeconomic background.     

Evaluation of potentially achievable vaccination coverage with simultaneous administration of vaccines among children in the United States

BackgroundRoutine administration of all age-appropriate doses of vaccines during the same visit is recommended for children by the National Vaccine Advisory Committee (NVAC) and the Advisory Committee on Immunization Practices (ACIP).MethodsEvaluate the potentially achievable vaccination coverage for ≥4 doses of diphtheria and tetanus toxoids and acellular pertussis vaccine (4+DTaP), ≥4 doses of pneumococcal conjugate vaccine (4+PCV), and the full series of Haemophilus influenzae type b vaccine (Hib-FS) with simultaneous administration of all recommended childhood vaccines. Compare the potentially achievable vaccination coverage to the reported vaccination coverage for calendar years 2001 through 2013; by state in the United States and by selected socio-demographic factors in 2013. The potentially achievable vaccination coverage was defined as the coverage possible for the recommended 4+DTaP, 4+PCV, and Hib-FS if missed opportunities for simultaneous administration of all age-appropriate doses of vaccines for children had been eliminated.ResultsCompared to the reported vaccination coverage, the potentially achievable vaccination coverage for 4+DTaP, 4+PCV, and Hib-FS could have increased significantly (P < 0.001), the vaccination coverage would have achieved the 90% target of Healthy People 2020 for the three vaccines beginning in 2005, 2008, and 2011 respectively. In 2013, the potentially achievable vaccination coverage increased significantly across all selected socio-demographic factors, potentially achievable vaccination coverage would have reached the 90% target for more than 51% of the states in the United States.ConclusionsThe findings in this study suggest that fully utilization of all opportunities for simultaneous administration of all age-eligible childhood doses of vaccines during the same vaccination visit is a critical strategy for achieving the vaccination coverage target of Healthy People 2020. Encouraging providers to deliver all recommended vaccines that are due at each visit by implementing client reminder and recall systems might decrease missed opportunities for simultaneous administration of childhood vaccines.     

Key points in evaluating immunogenicity of pandemic influenza vaccines: A lesson from immunogenicity studies of influenza A(H1N1)pdm09 vaccine

IntroductionImmunogenicity studies on pandemic influenza vaccine are necessary to inform rapid development and implementation of a vaccine during a pandemic. Thus, strategies for immunogenicity assessment are required.ObjectiveTo identify essential factors to consider when evaluating the immunogenicity of pandemic influenza vaccines using the experience in Japan with the influenza A(H1N1)pdm09 vaccine.MethodsWe conducted a search of observational studies using PubMed and IchushiWeb. Search terms included “influenza vaccine AND (immunogenicity OR immune response) AND Japan AND (2009 OR pdm09) NOT review,” and was limited to studies conducted in humans.ResultsA total of 33 articles were identified, of which 16 articles met the inclusion criteria. Immunogenicity of the commercially available influenza A(H1N1)pdm09 vaccine satisfied the international criteria for influenza vaccine immunogenicity in all study populations. The most remarkable immune response was observed in junior high school students, while the lowest immune response was observed in hematological malignancy patients. Similar to immunogenicity studies on seasonal influenza vaccines, factors such as patient background (e.g., age, underlying condition, pre-vaccination titer, body mass index, etc.) and study procedure (e.g., concurrent measurement of pre- and post-vaccination antibody titer, effects of infection during the study period) may have affected the assessment of immunogenicity to the influenza A(H1N1)pdm09 vaccine. In addition, prior vaccination with the seasonal influenza vaccine may inhibit antibody induction by the influenza A(H1N1)pdm09 vaccine.ConclusionsThis review discusses factors and strategies that must be considered and addressed during immunogenicity assessments of pandemic influenza vaccines, which may provide useful information for future influenza pandemics.     

Effectiveness of hospital-based strategies for improving childhood immunization coverage: A systematic review

BackgroundHospital settings represent an opportunity to offer and/or promote childhood vaccination. The purpose of the systematic review was to assess the effectiveness of different hospital-based strategies for improving childhood vaccination coverage.MethodsA systematic search of multiple bibliographic databases, thesis databases, and relevant websites was conducted to identify peer-reviewed articles published up to September 20, 2021. Articles were included if they evaluated the impact of a hospital (inpatient or emergency department)-based intervention on childhood vaccination coverage, were published in English or French, and were conducted in high-income countries. High quality studies were included in a narrative synthesis.ResultsWe included 25 high quality studies out of 7,845 unique citations. Studies focused on routine, outbreak, and influenza vaccines, and interventions included opportunistic vaccination (i.e. vaccination during hospital visit) (n = 7), patient education (n = 2), community connection (n = 2), patient reminders (n = 2), and opportunistic vaccination combined with patient education and/or reminders (n = 12). Opportunistic vaccination interventions were generally successful at improving vaccine coverage, though results ranged from no impact to vaccinating 71 % of eligible children with routine vaccines and 9–61 % of eligible children with influenza vaccines. Interventions that aimed to increase vaccination after hospital discharge (community connection, patient education, reminders) were less successful.ConclusionsSome interventions that provide vaccination to children accessing hospitals improved vaccine coverage; however, the baseline coverage level of the population, as well as implementation strategies used impact success. There is limited evidence that interventions promoting vaccination after hospital discharge are more successful if they are tailored to the individual.     

Estimating global changes in routine childhood vaccination coverage during the COVID-19 pandemic, 2020–2021

ObjectivesThe COVID-19 pandemic has disrupted the distribution of routine immunizations globally. Multi-country studies assessing a wide spectrum of vaccines and their coverage rates are needed to determine global performance in achieving vaccination goals.MethodsGlobal vaccine coverage data for 16 antigens were obtained from WHO/UNICEF Estimates of National Immunization Coverage. Tobit regression was performed for all country-antigen pairs for which data were continuously available between 2015–2020 or 2015–2021 to predict vaccine coverage in 2020/2021. Vaccines for which multi-dose data were available were assessed to determine whether vaccine coverage for subsequent doses were lower than that of first doses.ResultsVaccine coverage was significantly lower-than-predicted for 13/16 antigens in 2020 and all assessed antigens in 2021. Lower-than-predicted vaccine coverage was typically observed in South America, Africa, Eastern Europe, and Southeast Asia. There was a statistically significant coverage drop for subsequent doses of the diphtheria-tetanus-pertussis, pneumococcus, and rotavirus vaccines compared to first doses in 2020 and 2021.ConclusionThe COVID-19 pandemic exerted larger disruptions to routine vaccination services in 2021 than in 2020. Global efforts will be needed to recoup vaccine coverage losses sustained during the pandemic and broaden vaccine access in areas where coverage was previously inadequate.     

National vaccine coverage trends and funding in Latin America and the Caribbean

BackgroundFrom 2006 to 2011 nearly 174,000 deaths were prevented in Latin America and the Caribbean through vaccination of children under five, which is widely attributed to the Expanded Program on Immunization (EPI). Despite near global adoption of EPI recommendations, vaccination coverage shows substantial variation across world regions. Causes for low immunizations within regions are multifaceted and include vaccination program costs. To date, publications regarding vaccine coverage across Latin America and the Caribbean are not readily available. This study aimed to: (1) compare vaccine coverage trends across nations within the region; and (2) assess whether national immunization program expenditures are correlated with vaccine coverage.MethodsCoverage for nine vaccines were collected by nation using publicly available data from WHO. National immunization program expenditures for each country were collected from the World Bank Index. The proportion of countries achieving 90% coverage in the years 2013 and 2017 for each vaccine were compared. Pearson correlation coefficients were calculated to measure the relationship between financing variables and DTP3 coverage for 2017.ResultsIn 2017, fewer Latin American and Caribbean nations were able to achieve 90% vaccine coverage for five vaccines compared to 2013. Mostly weak to moderate positive relationships were found between national immunization program expenditures and DTP3 coverage for 2017. Excluding Haiti, a weak negative relationship was found between total government expenditure on vaccines per infant and DTP3 coverage for 2017. Countries across Latin America and the Caribbean were largely self-reliant in funding vaccine expenditures.ConclusionsFewer countries across Latin America and the Caribbean are currently achieving optimum national vaccine coverage and weak to moderate relationships between routine immunization and vaccine expenditures and coverage were observed. Additional factors contributing to national vaccine coverage should be concomitantly examined to implement strategies which optimize delivery of childhood immunizations.     

Implementation of maternal influenza immunization in El Salvador: Experiences and lessons learned from a mixed-methods study

IntroductionThe World Health Organization (WHO) recommends that countries prioritize pregnant women for influenza vaccination, yet few low- or middle-income countries (LMICs) have implemented maternal influenza immunization programs. To inform vaccine decision-making and operational planning in LMICs, there is a need to document and share experiences from countries that provide seasonal influenza vaccine to pregnant women, particularly those with high coverage, like El Salvador.MethodsIn 2015 and 2016, PATH and country researchers conducted a mixed-methods study to document the experience and lessons learned from maternal influenza immunization delivery and acceptance in El Salvador as part of a collaborative effort between WHO and PATH. Researchers conducted focus group discussions, semi-structured interviews, antenatal clinic exit interviews, and key informant interviews with 326 participants from two municipalities in each of the country’s three regions. Respondents included pregnant and recently pregnant women, family members, community leaders, health personnel, public health managers and partners, and policymakers.ResultsFactors perceived as positively influencing maternal influenza immunization delivery and acceptance in El Salvador include the use of multiple vaccine delivery strategies, targeted education and community engagement efforts, and a high degree of trust between the community and health care providers. Influenza vaccine acceptance by pregnant women is high and has improved over time, largely attributed to education targeting health care advisors. Perceived challenges to pregnant women receiving health care and vaccination include the need for permission to attend services and limited access to health services in insecure areas related to the presence of criminal gang activity.ConclusionsWe identified approaches and barriers perceived to affect maternal influenza vaccine delivery in El Salvador. This information will be useful to public health decision-makers and implementers in El Salvador and other countries considering introduction of new maternal vaccines or striving to increase coverage of vaccines currently provided.     

Maternal immunization in Malawi: A mixed methods study of community perceptions,programmatic considerations,and recommendations for future planning

BackgroundSafe, effective vaccines are given to pregnant women to protect their infants and/or themselves against certain infectious agents; however, apart from tetanus vaccination, maternal immunization in low- and middle-income countries (LMICs) remains low. Tetanus toxoid vaccine is integrated into antenatal care services in Malawi with high coverage and provides an opportunity to identify factors that facilitate successful immunization delivery to pregnant women in LMICs.MethodsPATH and the University of Malawi’s Centre for Social Research conducted a mixed-methods study in 2015 to document community perceptions of maternal immunization, using tetanus vaccine as an example, and to identify factors perceived to be important to successfully introducing other maternal vaccines, such as influenza vaccine, in Malawi. We conducted 18 focus group discussions with pregnant and recently pregnant women and their family members and 76 semi-structured interviews with pregnant and recently pregnant women, community leaders, health workers, public health program managers, non-governmental partners, and policy makers.ResultsWe identified factors perceived to support the introduction of new maternal vaccines, including strong maternal vaccine acceptance in the community, an existing strategy for maternal tetanus vaccine delivery, and positive health workers’ views about the introduction of additional maternal vaccines. Potential challenges to adoption and acceptance included identifying and tracking the target population and monitoring adverse events, and the need to ensure operational capacity of the health system to support the introduction and wide-scale use of an additional vaccine. For influenza vaccine specifically, additional challenges included limited awareness of influenza disease and its low prioritization among health needs.ConclusionsLessons from the successful delivery of maternal tetanus immunization in Malawi may be informative for similar countries considering new vaccines for pregnant women or striving to optimize the delivery of those currently provided.     

Uptake and timeliness of rotavirus vaccination in Norway: The first year post-introduction

BackgroundTo minimise vaccine-associated risk of intussusception following rotavirus vaccination, Norway adopted very strict age limits for initiating and completing the vaccine series at the time rotavirus vaccination was included in the national immunisation programme, October 2014. Although Norway has a high coverage for routine childhood vaccines, these stringent age limits could negatively affect rotavirus coverage. We documented the status and impact of rotavirus vaccination on other infant vaccines during the first year after its introduction.MethodsWe used individual vaccination data from the national immunisation register to calculate coverage for rotavirus and other vaccines and examine adherence with the recommended schedules. We identified factors associated with completing the full rotavirus series by performing multiple logistic regression analyses. We also evaluated potential changes in uptake and timeliness of other routine vaccines after the introduction of rotavirus vaccine using the Kaplan-Meier method.ResultsThe national coverage for rotavirus vaccine achieved a year after the introduction was 89% for one dose and 82% for two doses, respectively. Among fully rotavirus-vaccinated children, 98% received both doses within the upper age limit and 90% received both doses according to the recommended schedule. The child’s age at the initiation of rotavirus series and being vaccinated with diphtheria, tetanus, pertussis, polio and Haemophilus influenzae type b (DTaP/IPV/Hib) and pneumococcal vaccines were the strongest predictors of completing the full rotavirus series. No major changes in uptake and timeliness of other paediatric vaccines were observed after introduction of rotavirus vaccine.ConclusionsNorway achieved a high national coverage and excellent adherence with the strict age limits for rotavirus vaccine administration during the first year of introduction, indicating robustness of the national immunisation programme. Rotavirus vaccination did not impact coverage or timeliness of other infant vaccines.     

Barriers and activities to implementing or expanding influenza vaccination programs in low- and middle-income countries: A global survey

IntroductionDespite considerable global burden of influenza, few low- and middle-income countries (LMICs) have national influenza vaccination programs. This report provides a systematic assessment of barriers to and activities that support initiating or expanding influenza vaccination programs from the perspective of in-country public health officials.MethodsPublic health officials in LMICs were sent a web-based survey to provide information on barriers and activities to initiating, expanding, or maintaining national influenza vaccination programs. The survey primarily included Likert-scale questions asking respondents to rank barriers and activities in five categories.ResultsOf 109 eligible countries, 62% participated. Barriers to influenza vaccination programs included lack of data on cost-effectiveness of influenza vaccination programs (87%) and on influenza disease burden (84%), competing health priorities (80%), lack of public perceived risk from influenza (79%), need for better risk communication tools (77%), lack of financial support for influenza vaccine programs (75%), a requirement to use only WHO-prequalified vaccines (62%), and young children require two vaccine doses (60%). Activities for advancing influenza vaccination programs included educating healthcare workers (97%) and decision-makers (91%) on the benefits of influenza vaccination, better estimates of influenza disease burden (91%) and cost of influenza vaccination programs (89%), simplifying vaccine introduction by focusing on selected high-risk groups (82%), developing tools to prioritize target populations (80%), improving availability of influenza diagnostic testing (79%), and developing collaborations with neighboring countries for vaccine procurement (74%) and regulatory approval (73%). Responses varied by country region and income status.ConclusionsLocal governments and key international stakeholders can use the results of this survey to improve influenza vaccination programs in LMICs, which is a critical component of global pandemic preparedness for influenza and other pathogens such as coronaviruses. Additionally, strategies to improve global influenza vaccination coverage should be tailored to country income level and geographic location.     

COVID-19 vaccination hesitancy in people affected by diabetes and strategies to increase vaccine compliance: A systematic narrative review and meta-analysis

IntroductionPeople affected by diabetes are at higher risk for complications from certain vaccine-preventable diseases. Suboptimal vaccination coverages are reported in this population sub-group. The purpose of this study is to estimate the proportion of diabetic patients who express hesitation to the COVID-19 vaccine worldwide.MethodsSeven studies were included in the meta-analysis and systematic review, selected from scientific articles available in the MEDLINE/PubMed, Google Scholar and Scopus databases from 2020 to 2022. The following terms were used for the search strategy: (adherence OR hesitancy OR compliance OR attitude) AND (covid* OR SARS*) AND (vaccin* OR immun*) AND (diabet*).ResultsThe vaccine hesitation rate among persons with diabetes was 27.8 % (95 %CI = 15.6–41.9 %). In the comparison of vaccine hesitancy between sexes and educational status, the RRs were 0.90 (95 %CI = 0.71–1.15) and 0.88 (95 %CI = 0.76–1.02), respectively. The main reasons of unwillingness were lack of information, opinion that the vaccine was unsafe or not efficient, and fear of adverse events.ConclusionsIn order to achieve a high vaccination coverage, multifactorial approach is needed, which requires major social, scientific and health efforts. The success of the vaccination campaign in this population depends on the capillarity and consistency of the interventions implemented.     

Coverage and timeliness of vaccination and the validity of routine estimates: Insights from a vaccine registry in Kenya

BackgroundThe benefits of childhood vaccines are critically dependent on vaccination coverage. We used a vaccine registry (as gold standard) in Kenya to quantify errors in routine coverage methods (surveys and administrative reports), to estimate the magnitude of survivor bias, contrast coverage with timeliness and use both measures to estimate population immunity.MethodsVaccination records of children in the Kilifi Health and Demographic Surveillance System (KHDSS), Kenya were combined with births, deaths, migration and residence data from 2010 to 17. Using inverse survival curves, we estimated up-to-date and age-appropriate vaccination coverage, calculated mean vaccination coverage in infancy as the area under the inverse survival curves, and estimated the proportion of fully immunised children (FIC). Results were compared with published coverage estimates. Risk factors for vaccination were assessed using Cox regression models.ResultsWe analysed data for 49,090 infants and 48,025 children aged 12–23 months in 6 birth cohorts and 6 cross-sectional surveys respectively, and found 2nd year of life surveys overestimated coverage by 2% compared to birth cohorts. Compared to mean coverage in infants, static coverage at 12 months was exaggerated by 7–8% for third doses of oral polio, pentavalent (Penta3) and pneumococcal conjugate vaccines, and by 24% for the measles vaccine. Surveys and administrative coverage also underestimated the proportion of the fully immunised child by 10–14%. For BCG, Penta3 and measles, timeliness was 23–44% higher in children born in a health facility but 20–37% lower in those who first attended during vaccine stock outs.ConclusionsStandard coverage surveys in 12–23 month old children overestimate protection by ignoring timeliness, and survivor and recall biases. Where delayed vaccination is common, up-to-date coverage will give biased estimates of population immunity. Surveys and administrative methods also underestimate FIC prevalence. Better measurement of coverage and more sophisticated analyses are required to control vaccine preventable diseases.     

Survey of vaccination knowledge and acceptance among adults admitted to an urban emergency department

BackgroundAdult vaccination rates in the United States have fallen below national target levels and may be exacerbated by lack of access to a primary care physician. We assessed patient knowledge of and attitudes towards vaccines in an urban emergency department population and analyzed the feasibility of using this setting as a vaccine delivery site from a patient perspective.MethodsIn-person interviewers administered surveys to 250 adult patients presenting to the Detroit Receiving Hospital emergency department in Detroit, Michigan. Respondents were asked about vaccination status, preferences, and willingness to accept vaccination reminders via text messaging. Odds ratios and 95% Wald confidence intervals assessing differences between vaccinated and non-vaccinated individuals were generated with univariate logistic regression.ResultsVaccinated adults were more likely to have a primary care provider than non-vaccinated adults (OR 1.94, 95% CI: 1.09–3.45). Non-vaccinated adults were significantly more likely to have unvaccinated adult relatives (OR8.64, 95% CI: 4.10–18.22). Nearly all respondents used a cell phone, and 75.8% of unvaccinated adults were willing to receive text messages reminders about vaccines.ConclusionsAlthough less likely to have a primary care access point than vaccinated participants, non-vaccinated respondents reported interest in receiving vaccinations. Emergency departments could serve as vaccination hubs for patients and unvaccinated accompanying family members. Text message reminders offer a potential source of additional vaccine prompts and education.