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.     

Acceptance and feasibility of school-based seasonal influenza vaccination in Singapore: A qualitative study

IntroductionInfluenza is a major cause of disease in children. School-based seasonal influenza vaccination can be a cost-effective tool to improve vaccine uptake among children, and can bring substantial health and economic benefits to the broader community. The acceptance and feasibility of school-based influenza vaccination are likely to be highly context-specific, but limited data exist from tropical settings with year-round influenza transmission. We conducted a qualitative study to assess acceptability and feasibility of a school-based seasonal influenza vaccination programme in Singapore.MethodsWe conducted qualitative in-depth interviews with key stakeholders, including healthcare professionals, representatives of relevant ministries, preschool principals and parents to understand their perspectives on a proposed school-based seasonal influenza vaccination programme. Interviews were transcribed verbatim and analysed using thematic analysis.ResultsWe conducted 40 interviews. Although preschool-aged children are currently the recommended age group for vaccination, stakeholders suggested introducing the programme in primary and/or secondary schools, where existing vaccination infrastructure would facilitate delivery. However, more comprehensive evidence on the local influenza burden and transmission patterns among children is required to develop an evidence-based, locally relevant rationale for a school-based vaccination programme and effectively engage policy-makers, school staff, and parents. Extensive, age-appropriate public education and awareness campaigns would increase the acceptability of the programme among stakeholders. Stakeholders indicated that an opt-out programme with free or subsidised vaccination would be the most likely to achieve high vaccine coverage and make access to vaccination more equitable.ConclusionsOverall, participants were supportive of a free or subsidised school-based influenza vaccination programme in primary and/or secondary schools, although children in this age group are not currently a recommended group for vaccination. However, a better informed, evidence-based rationale to estimate the programme’s impact in Singapore is currently lacking. Extensive, age-appropriate public education and awareness campaigns will help ensure full support across key stakeholder groups.     

Influenza vaccine viruses and the development of seasonal vaccines: A Japanese perspective

In Japan, the Ministry of Health, Labour and Welfare (MHLW) designates one specific virus strain for each component of the quadrivalent seasonal influenza vaccine, and four domestic manufacturers produce egg-based influenza vaccines with the same formulation (inactivated, split-virus) using uniform vaccine strains. Thus, discussions of the development of effective seasonal influenza vaccines so far has focused solely on the antigenic match between the vaccine strains and epidemic viruses. However, in 2017, the Japanese selection system of vaccine viruses demonstrated that even a candidate vaccine virus that is antigenically similar to the predicted circulating viruses is not necessarily suitable for vaccine production, given lower productivity of the vaccine. Taking this experience into account, the MHLW reformed the scheme of vaccine strain selection in 2018, and instructed the Vaccine Epidemiology Research Group created by the MHLW to probe how the virus strains for the seasonal influenza vaccine should be selected in Japan. In this context, a symposium, entitled “Issues of the Present Seasonal Influenza Vaccines and Future Prospects”, was held as part of the 22nd Annual Meeting of the Japanese Society for Vaccinology in 2018, and subjects related to the influenza vaccine viruses were discussed among relevant administrators, manufacturers, and researchers. This report summarizes the presentations given at that symposium in order to convey the present scheme of vaccine virus selection, the evaluation of the resulting vaccines, and the efforts at new vaccine formulation in Japan. Notably, from March 2022, the MHLW has launched a discussion of the merits of the seasonal influenza vaccines produced by foreign manufacturers.     

PIPDeploy: Development and implementation of a gamified table top simulation exercise to strengthen national pandemic vaccine preparedness and readiness

Successful emergency vaccination campaigns rely on effective deployment and vaccination plans. This applies to localised outbreaks as well as for pandemics. In the wake of the 2009 H1N1 influenza pandemic, analysis of the global Vaccine Deployment Initiative, through which the World Health Organization (WHO) donated pandemic influenza vaccines to countries in need, revealed that an absence of vaccine deployment plans in many countries significantly hindered vaccine deployment. Through the Pandemic Influenza Preparedness Framework adopted by the World Health Assembly in 2011, WHO is engaging in several capacity building activities to improve pandemic influenza preparedness and response and make provisions for access to vaccines and sharing of other benefits. The Framework calls for the development and exercise of operational plans for deployment of influenza vaccines to enhance pandemic preparedness. To this end, WHO has supported the development of PIPDeploy, an interactive, in-person table top simulation exercise to facilitate learning for emergency preparedness. It employs various game design elements including a game board, time pressure, leaderboards and teams to enhance participants’ motivation. PIPDeploy formed part of five WHO Pandemic Influenza Vaccine Deployment Workshops attended by national-level managers responsible for pandemic influenza vaccine response predominantly in non-producing countries. The purpose of this study was to describe the features and application of PIPDeploy, and present findings of the evaluation of participants’ experiences during the simulation involving a “hot wash” discussion and collection of quantitative data. The simulation’s instructional approach was widely accepted by participants, who reported that the format was novel and engaging. They reflected on its utility for identifying gaps in their own vaccine deployment plans and regulatory frameworks for importation of vaccine products. All participants found the simulation relevant to their professional objectives. A range of other potential applications were suggested, including PIPDeploy’s adaptation to sub-national contexts and to other epidemic diseases.     

A Research and Development (R&D) roadmap for influenza vaccines: Looking toward the future

Improved influenza vaccines are urgently needed to reduce the burden of seasonal influenza and to ensure a rapid and effective public-health response to future influenza pandemics. The Influenza Vaccines Research and Development (R&D) Roadmap (IVR) was created, through an extensive international stakeholder engagement process, to promote influenza vaccine R&D. The roadmap covers a 10-year timeframe and is organized into six sections: virology; immunology; vaccinology for seasonal influenza vaccines; vaccinology for universal influenza vaccines; animal and human influenza virus infection models; and policy, finance, and regulation. Each section identifies barriers, gaps, strategic goals, milestones, and additional R&D priorities germane to that area. The roadmap includes 113 specific R&D milestones, 37 of which have been designated high priority by the IVR expert taskforce. This report summarizes the major issues and priority areas of research outlined in the IVR. By identifying the key issues and steps to address them, the roadmap not only encourages research aimed at new solutions, but also provides guidance on the use of innovative tools to drive breakthroughs in influenza vaccine R&D.     

Global production capacity of seasonal and pandemic influenza vaccines in 2019

Vaccines will be an important element in mitigating the impact of an influenza pandemic. While research towards developing universal influenza vaccines is ongoing, the current strategy for vaccine supply in a pandemic relies on seasonal influenza vaccine production to be switched over to pandemic vaccines. Understanding how much vaccine could be produced, in which regions of the world and in what timeframe is critical to informing influenza pandemic preparedness. Through the Global Action Plan for Influenza Vaccines, 2006–2016, WHO promoted an increase in vaccine production capacity and monitors the landscape through periodically surveying influenza vaccine manufacturers. This study compares global capacity for production of influenza vaccines in 2019 with estimates from previous surveys; provides an overview of countries with established production facilities; presents vaccine production by type and manufacturing process; and discusses limitations to these estimates. Results of the current survey show that estimated annual seasonal influenza vaccine production capacity changed little since 2015 increasing from 1.47 billion to 1.48 billion doses with potential maximum annual influenza pandemic vaccine production capacity increasing from 6.37 billion to 8.31 billion doses. However, this figure should be interpreted with caution as it presents a best-case scenario with several assumptions which may impact supply. Further, pandemic vaccines would not be immediately available and could take four to six months for first supplies with several more months needed to reach maximum capacity. A moderate-case scenario is also presented of 4.15 billion doses of pandemic vaccine in 12 months. It is important to note that two doses of pandemic vaccine are likely to be required to elicit an adequate immune response. Continued efforts are needed to ensure the sustainability of this production and to conduct research for vaccines that are faster to produce and more broadly protective taking into account lessons learned from COVID-19 vaccine development.     

Contributions of cost-effectiveness analyses (CEA) to influenza vaccination policy for older adults in Europe

This review describes the importance of economic evaluations and real-world evidence (RWE) for the assessment of enhanced influenza vaccines for older adults in Europe. Individuals ≥65 years of age are at increased risk of severe influenza outcomes and many countries in Europe recommend enhanced vaccines for this population to mitigate immunosenescence. Some National Immunization Technical Advisory Groups (NITAGs) may preferentially recommend a specific enhanced vaccine, necessitating comparative economic evaluation and estimation of relative vaccine effectiveness between enhanced vaccine options in the absence of direct head-to-head efficacy data. Distinct approaches to economic modeling and cost-effectiveness analysis (CEA) guide national vaccination policies in Europe, including how underlying data, such as RWE, are used in these models. RWE is an important evidence source for input into CEA models based on disease factors (e.g., antigenic shift and seasonal variation) and practical factors (e.g., limitations of performing multiple randomized clinical trials to capture seasonal variation; the need to obtain relevant patient-oriented, real-world endpoints, such as hospitalizations). CEA is considered crucial to vaccine assessment among certain countries in Europe, but further harmonization of economic evaluations, including the use of RWE, across NITAGs in Europe may be of benefit, alongside standardized approaches for vaccine appraisal. In the future, more countries may use RWE as an input in CEA models to support NITAG recommendations for enhanced influenza vaccines in older populations, especially considering the value of RWE for the assessment of influenza epidemiology and vaccine effectiveness as stated by the World Health Organization, and the availability of a broad RWE base for certain enhanced vaccines.     

Cost-effectiveness of introducing an MF59-adjuvanted trivalent influenza vaccine for older adults in Argentina

IntroductionInfluenza surveillance in Argentina reported influenza-like illness at a rate of 3500/100,000, a hospitalization rate of 15.5/100,000, and a death rate of 0.32/100,000 annually in adults aged over 65 years. The high burden of disease may be due to a combination of immunosenescence and the suboptimal clinical effectiveness of conventional, non-adjuvanted influenza vaccines in this age group. There is a clinical need for more effective influenza vaccines in this population. This study evaluated the cost-effectiveness of an MF59®-adjuvanted trivalent influenza vaccine (aTIV) in adults aged over 65 years in Argentina compared with the non-adjuvanted trivalent influenza vaccine (TIV) used under the current national vaccination policy.MethodsA decision tree cost-effectiveness model was developed to estimate the cost-effectiveness of switching from TIV to aTIV in Argentinian older adults. The model compared cost and health benefits of vaccination in one influenza season from the payer perspective. The main predictions included survival, quality-adjusted survival, and costs. Model inputs were sourced from Argentina or internationally where local data was considered inaccurate. Vaccine efficacy assumptions were extracted from recently published, peer-reviewed scientific literature.ResultsSwitching from TIV to aTIV would result in 170 deaths averted and 1310 incremental quality-adjusted life years (QALYs) gained. The incremental cost-effectiveness ratio per QALY was US $2660.59 from the payer perspective. In all sensitivity analyses, aTIV remained highly cost-effective. The probabilistic sensitivity analyses showed a 95% CI per QALY of US $113.74–7721.67.ConclusionIntroducing an adjuvanted influenza vaccine in Argentina is potentially beneficial and cost-effective relative to the currently-used TIV through the reduction of disease burden and utilization of healthcare resources.     

“The flu… is a little more complicated than a cold”: Knowledge,beliefs, and practices related to influenza and influenza vaccination among at-risk populations and health professionals in Peru

BackgroundInfluenza is a major source of morbidity and mortality with an annual global attack rate estimated at 5–10% in adults and 20–30% in children. Influenza vaccination is the main strategy for reducing influenza-related morbidity and mortality. Like several other countries, Peru has low vaccination coverage, estimated at 25–50% among young children and older adults. Therefore, the study objective was to explore the knowledge, beliefs, attitudes, and practices related to influenza vaccination among populations at higher risk for infection and/or complications and health professionals in Peru, and their perspectives on health communication channels.MethodsThis qualitative study was carried out in three cities. We held nine focus groups with pregnant and postpartum women, parents of young children, and older adults. We carried out 25 in-depth interviews with health professionals (HPs) working in, leading or advising immunization-related programs.ResultsHPs correctly identified the causes of influenza and HPs and at risk community members identified major symptoms. Community members had poor awareness of the potential severity of influenza and were generally unaware of influenza-related mortality. Both HPs and community members greatly underestimated the prevalence of influenza in Peru. HPs in our study overestimated major side effects of the influenza vaccine and community members perceived that the vaccine caused illness. HPs missed important opportunities to promote vaccination in patients with minor illness (runny nose, allergies, colds) and community members did not understand that the vaccine should be received annually.ConclusionsThere is no single strategy that will increase influenza vaccination rates to World Health Organization recommended levels. Instead, it requires multi-faceted commitment from HPs, other healthcare authorities and the government. Addressing important knowledge barriers, specifically negative views regarding the influenza vaccine and the severe morbidity and mortality associated with influenza illness, both in the community and especially among HPs, could have significant impacts.     

Using classification and regression tree analysis to explore parental influenza vaccine decisions

Background and objectivesInfluenza poses a public health threat for children and adults. The CDC recommends annual influenza vaccination for children <18 years, yet vaccine uptake remains low for children (57.9%) and adults (37.1%). Given that parental decision-making is key in childhood vaccine uptake, there is a critical need to understand vaccine hesitancy among parents who decide not to vaccinate their children. This study aims to explore predictors of children’s influenza vaccine status given parental vaccination status and examine the factors that contribute to concordance or discordance between parental and children’s vaccine uptake.MethodsClassification and regression tree (CART) analyses were used to identify drivers of parental decisions to vaccinate their children against influenza. Hierarchy and interactions of these variables in predicting children’s vaccination status were explored.ResultsFrom a nationally representative sample of non-Hispanic Black and White parents who completed an online survey (n = 328), the main factors influencing parents’ decisions to vaccinate their children were vaccine behavior following physician recommendation, knowledge of influenza recommendations for children, influenza vaccine confidence and disease risk. Among unvaccinated parents, the greatest concordance was observed among parents who usually do not get vaccinated following physician recommendation and had lower knowledge of recommendations for influenza vaccination for children. The greatest discordance was observed among unvaccinated parents who had lower hesitancy about recommended vaccines.ConclusionsUnderstanding drivers of parental decisions to vaccinate themselves and their children can provide insights on health communication and provider approaches to increase influenza vaccine coverage and prevent influenza related mortality.     

Maternal influenza vaccination and child mortality: Longitudinal,population-based linked cohort study

Influenza vaccination is recommended to protect mothers and their infants from influenza. Few studies have evaluated the association between maternal influenza vaccination and child mortality. We aimed to evaluate the association between in utero exposure to seasonal inactivated influenza vaccine (IIV) and mortality among young children. This longitudinal, population-based cohort study included 191,247 maternal-child pairs in Western Australia between April 2012 and December 2017. Maternal vaccine information was obtained from a state-wide antenatal vaccination database. Mortality was defined as a record of a death registration. We used Cox proportional hazard models, weighted by the inverse-probability of treatment (vaccination), to estimate the hazard ratio of child mortality associated with in utero exposure to seasonal IIV. This study found no association between in utero exposure to seasonal IIV and mortality through age five years.     

Identifying signatures of the impact of rotavirus vaccines on hospitalizations using sentinel surveillance data from Latin American countries

BackgroundPassive surveillance data are often the only available source of data that can be used to evaluate the population-level impact of vaccination, but such data often suffer from important limitations such as changes in surveillance efforts. This study provides an example of how to identify important signatures of rotavirus vaccine impact, including evaluating the overall effectiveness and changes in rotavirus seasonal dynamics.MethodsWe used data from a standardized sentinel rotavirus surveillance network in six Latin American countries (Bolivia, El Salvador, Guatemala, Honduras, Paraguay, and Venezuela) from 2004 to 2017. A random-effects model was used to evaluate changes in the proportion of rotavirus-associated hospitalizations following vaccine introduction. Harmonic regression models were used to estimate vaccine impact on the number of rotavirus hospitalizations, controlling for trends in rotavirus-negative cases. Changes to rotavirus seasonality were evaluated using center of gravity analysis, wavelet analysis, and harmonic regression.ResultsAll countries observed declines in the proportion of rotavirus-positive acute diarrhea samples with a mean reduction of 16% (95% confidence interval: 10–22%). We estimate that each 10% increase in vaccine coverage was associated with declines in the number of rotavirus-positive cases, ranging from 4.3% (1.3–7.2%) in Honduras to 21.4% (16.8–25.9%) in Venezuela. The strength of the seasonal peak in rotavirus incidence became smaller after vaccine introduction in Guatemala, Honduras, and Venezuela. Seasonal peaks also shifted later in the surveillance year, especially in higher-mortality countries.ConclusionsThe combination of methods we applied have different strengths that allow us to identify common signatures of rotavirus vaccine impact.     

Inactivated influenza vaccine formulated with single-stranded RNA-based adjuvant confers mucosal immunity and cross-protection against influenza virus infection

Influenza vaccination is considered the most valuable means to prevent and control seasonal influenza infections, which causes various clinical symptoms, ranging from mild cough and fever to even death. Among various influenza vaccine types, the inactivated subunit type is known to provide improved safety with reduced reactogenicity. However, there are some drawbacks associated with inactivated subunit type vaccines, with the main ones being its low immunogenicity and the induction of Th2-biased immune responses. In this study, we investigated the role of a single-stranded RNA (ssRNA) derived from the intergenic region in the internal ribosome entry site of the Cricket paralysis virus as an adjuvant rather than the universal vaccine for a seasonal inactivated subunit influenza vaccine. The ssRNA adjuvant stimulated not only well-balanced cellular (indicated by IgG2a, IFN-γ, IL-2, and TNF-α) and humoral (indicated by IgG1 and IL-4) immune responses but also a mucosal immune response (indicated by IgA), a key protector against respiratory virus infections. It also increases the HI titer, the surrogate marker of influenza vaccine efficacy. Furthermore, ssRNA adjuvant confers cross-protective immune responses against heterologous influenza virus infection while promoting enhanced viral clearance. Moreover, ssRNA adjuvant increases the number of memory CD4⁺ and CD8⁺ T cells, which can be expected to induce long-term immune responses. Therefore, this ssRNA-adjuvanted seasonal inactivated subunit influenza vaccine might be the best influenza vaccine generating robust humoral and cellular immune responses and conferring cross-protective and long-term immunity.     

Influenza vaccination coverage among persons seeking outpatient medical care for acute respiratory illness in five states in the United States, 2011–2012 through 2018–2019

BackgroundIn the United States (U.S.), annual influenza vaccination has been recommended for all persons aged ≥6 months with the Healthy People 2020 coverage target of 70%. However, vaccination coverage has remained around 42–49% during the past eight influenza seasons. We sought to quantify influenza vaccination coverage and factors associated with vaccination in persons seeking outpatient medical care for an acute respiratory illness (ARI).MethodsWe enrolled outpatients aged ≥6 months with ARI from >50 U.S. clinics from 2011 to 2012 through 2018–2019 influenza seasons and tested for influenza with molecular assays. Vaccination status was based on documented receipt of the current season’s influenza vaccine. We estimated vaccination coverage among influenza-negative study participants by study site, age, and season, and compared to state-level influenza coverage estimates in the general population based on annual immunization surveys. We used multivariable logistic regression to examine factors independently associated with receipt of influenza vaccines.ResultsWe enrolled 45,424 study participants with ARI who tested negative for influenza during the study period. Annual vaccination coverage among influenza-negative ARI patients and the general population in the participating states averaged 55% (range: 47–62%), and 52% (range: 46–54%), respectively. Among enrollees, coverage was highest among adults aged ≥65 years (82%; range, 80–85%) and lowest among adolescents aged 13–17 years (38%; range, 35–41%). Factors significantly associated with non-vaccination included non-White race, no college degree, exposure to cigarette smoke, absence of high-risk conditions, and not receiving prior season influenza vaccine.ConclusionsInfluenza vaccination coverage over eight seasons among outpatients with non-influenza respiratory illness was slightly higher than coverage in the general population but 15% lower than national targets. Increased efforts to promote vaccination especially in groups with lower coverage are warranted to attain optimal health benefits of influenza vaccine.     

Cost-effectiveness of sub-national geographically targeted vaccination programs: A systematic review

Immunization is an essential component of national health plans. However, the growing number of new vaccine introductions, vaccination campaigns and increasing administrative costs create logistic and financial challenges, especially in resource-limited settings. Sub-national geographic targeting of vaccination programs is a potential strategy for governments to reduce the impact of infectious disease outbreaks while optimizing resource allocation and reducing costs, promoting sustainability of critically important national immunization plans. We conducted a systematic review of peer-reviewed literature to identify studies that investigated the cost-effectiveness of geographically targeted sub-national vaccination programs, either through routine immunization or supplementary immunization activities. A total of 16 studies were included in our review, covering nine diseases of interest: cholera, dengue, enterotoxigenic Escherichia coli (ETEC), hepatitis A, Japanese encephalitis, measles, rotavirus, Shigella and typhoid fever. All studies modelled cost-effectiveness of geographically targeted vaccination. Despite the variation in study design, disease focus and country context, studies generally found that in countries where a heterogenous burden of disease exists, sub-national geographic targeting of vaccination programs in areas of high disease burden was more cost-effective than a non-targeted strategy. Sensitivity analysis revealed that cost-effectiveness was most sensitive to variations in vaccine price, vaccine efficacy, mortality rate, administrative and operational costs, discount rate, and treatment costs. This systematic review identified several key characteristics related to geographic targeting of vaccination, including the vaccination strategy used, variations in modelling parameters and their impact on cost-effectiveness. Additional research and guidance is needed to support the appropriateness and feasibility of geographically targeted vaccination and to determine what country context would make this a viable complement to routine immunization programs.     

Influenza vaccination and respiratory virus interference among Department of Defense personnel during the 2017–2018 influenza season

PurposeReceiving influenza vaccination may increase the risk of other respiratory viruses, a phenomenon known as virus interference. Test-negative study designs are often utilized to calculate influenza vaccine effectiveness. The virus interference phenomenon goes against the basic assumption of the test-negative vaccine effectiveness study that vaccination does not change the risk of infection with other respiratory illness, thus potentially biasing vaccine effectiveness results in the positive direction. This study aimed to investigate virus interference by comparing respiratory virus status among Department of Defense personnel based on their influenza vaccination status. Furthermore, individual respiratory viruses and their association with influenza vaccination were examined.ResultsWe compared vaccination status of 2880 people with non-influenza respiratory viruses to 3240 people with pan-negative results. Comparing vaccinated to non-vaccinated patients, the adjusted odds ratio for non-flu viruses was 0.97 (95% confidence interval (CI): 0.86, 1.09; p = 0.60). Additionally, the vaccination status of 3349 cases of influenza were compared to three different control groups: all controls (N = 6120), non-influenza positive controls (N = 2880), and pan-negative controls (N = 3240). The adjusted ORs for the comparisons among the three control groups did not vary much (range: 0.46–0.51).ConclusionsReceipt of influenza vaccination was not associated with virus interference among our population. Examining virus interference by specific respiratory viruses showed mixed results. Vaccine derived virus interference was significantly associated with coronavirus and human metapneumovirus; however, significant protection with vaccination was associated not only with most influenza viruses, but also parainfluenza, RSV, and non-influenza virus coinfections.     

Body mass index and vaccine responses following influenza vaccination during pregnancy

Background and AimsInfluenza vaccination is recommended by the World Health Organisation for pregnant women, offering the dual benefit of protecting pregnant women and their newborn infants against influenza infection. Various factors can influence vaccine immunogenicity, with obesity being one factor implicated in varied responses. This study aimed to investigate the impact of body mass index (BMI) on vaccine responses following influenza vaccination during pregnancy.MethodsPregnant women attending the Women’s and Children’s Hospital in South Australia during 2014–2016 were invited to participate. Participant’s clinical and demographic factors were recorded prior to administration of licensed seasonal influenza vaccination. Blood samples were collected before and one month post-vaccination to measure antibody responses by haemagglutination inhibition (HI) assay. Seroprotection was defined as a post-vaccination HI titre ≥ 1:40. Regression models assessed associations with failure to achieve seroprotective antibodies to H1, H3, and B influenza strains.ResultsA total of 96 women were enrolled in the study at a median gestation of 22 weeks with a BMI range of 18–49 kg/m². Paired sera samples were available for 90/96 (94%). Most pregnant women (72/90, 80%) demonstrated seroprotective antibody titres to all three influenza vaccine antigens (A(H1N1)pdm09, A(H3N2), B/Yamagata) following vaccination. Compared with women with BMI < 30 kg/m², those with high BMI were less likely to fail to achieve seroprotective antibodies, however this was not statistically significant (RR 0.42, 95% CI 0.11–1.68; p = 0.22). A greater proportion of women vaccinated during their second (47/53, 93%) or third trimester (18/25, 72%) demonstrated seroprotection to all three vaccine antigens following vaccination compared with women vaccinated during their first trimester (7/12, 58%).ConclusionHigh BMI did not impair seroprotection levels following influenza vaccination in pregnant women. Gestation at vaccination may be an important consideration for optimising vaccine protection for pregnant women and their newborns. Further assessment of first trimester influenza vaccine responses is warranted.     

Influenza in the Asia-Pacific region: Findings and recommendations from the Global Influenza Initiative

The fourth roundtable meeting of the Global Influenza Initiative (GII) was held in Hong Kong, China, in July 2015. An objective of this meeting was to gain a broader understanding of the epidemiology, surveillance, vaccination policies and programs, and obstacles to vaccination of influenza in the Asia-Pacific region through presentations of data from Australia, Hong Kong, India, Indonesia, Malaysia, New Zealand, the Philippines, Taiwan, Thailand, and Vietnam.As well as a need for improved levels of surveillance in some areas, a range of factors were identified that act as barriers to vaccination in some countries, including differences in climate and geography, logistical challenges, funding, lack of vaccine awareness and education, safety concerns, perceived lack of vaccine effectiveness, and lack of inclusion in national guidelines. From the presentations at the meeting, the GII discussed a number of recommendations for easing the burden of influenza and overcoming the current challenges in the Asia-Pacific region. These recommendations encompass the need to improve surveillance and availability of epidemiological data; the development and publication of national guidelines, where not currently available and/or that are in line with those proposed by the World Health Organization; the requirement for optimal timing of vaccination programs according to local or country-specific epidemiology; and calls for advocacy and government support of vaccination programs in order to improve availability and uptake and coverage.In conclusion, in addition to the varied epidemiology of seasonal influenza across this diverse region, there are a number of logistical and resourcing issues that present a challenge to the development of optimally effective vaccination strategies and that need to be overcome to improve access to and uptake of seasonal influenza vaccines. The GII has developed a number of recommendations to address these challenges and improve the control of influenza.     

Influenza vaccination uptake among high-risk target groups and health care workers in Spain and change from 2017 to 2020

ObjectiveUsing the 2020 European Health Survey for Spain (EHSS2020), which ran from July 2019 to July 2020, we aimed to describe influenza vaccination uptake among the following target groups; individuals aged ≥65 years, health care workers (HCWs), and persons with high-risk chronic medical conditions. We analyzed changes in uptake since the previous Spanish National Health Interview Survey conducted in 2017 and identified variables associated with vaccine uptake.MethodsWe performed a cross-sectional study. The primary study variable was the self-reported uptake of influenza vaccine in the previous year. We analyzed sex, age, country of birth, and being an HCW. We identified participants with self-reported respiratory diseases, cardiovascular disease, diabetes, cancer, and cerebrovascular diseases. Multivariable logistic regression was applied to assess changes over time and to identify variables associated with vaccination in target groups.ResultsUptake was 19.2% in 22,072 participants aged ≥15 years. Uptake was 54.4% for those aged ≥65 years, 41.6% for those with a high-risk medical condition, and 26.53% among HCWs. Uptake by disease was 52.1% for cerebrovascular diseases, 51.3% for cardiovascular diseases, 48.3% for diabetes, 46.1% for cancer, and 36.2% for respiratory diseases. No significant improvement has been observed since 2017 in any target group, except for participants with cancer, whose uptake increased from 33.2% to 46.1%(p < 0.001).The variables that significantly increased the probability of reporting vaccine uptake were female sex, age ≥35 years, being born in Spain, self-reported respiratory or cardiovascular diseases, diabetes, cancer, and being a HCW.ConclusionsInfluenza vaccination uptake among target groups in Spain is below desirable levels and has not improved significantly since 2017. Older age, female sex, and being born in Spain are positive predictors of vaccine uptake.The COVID-19 pandemic highlights the urgent need to implement new strategies to increase influenza vaccine uptake.     

Differences and disparities in seasonal influenza vaccine,acceptance, adverse reactions,and coverage by age,sex, gender,and race

BackgroundInfluenza is a significant threat to public health worldwide. Despite the widespread availability of effective and generally safe vaccines, the acceptance and coverage of influenza vaccines are significantly lower than recommended. Sociodemographic variables are known to be potential predictors of differential influenza vaccine uptake and outcomes.ObjectivesThis review aims to (1) identify how sociodemographic characteristics such as age, sex, gender, and race may influence seasonal influenza vaccine acceptance and coverage; and (2) evaluate the role of these sociodemographic characteristics in differential adverse reactions among vaccinated individuals.MethodsPubMed was used as the database to search for published literature in three thematic areas related to the seasonal influenza vaccine - vaccine acceptance, adverse reactions, and vaccine coverage.ResultsA total of 3249 articles published between 2010 and 2020 were screened and reviewed, of which 39 studies were included in this literature review. By the three thematic areas, 17 studies assessed vaccine acceptance, 8 studies focused on adverse reactions, and 14 examined coverage of the seasonal influenza vaccine. There were also two studies that focused on more than one of the areas of interest.ConclusionEach of the four sociodemographic predictors – age, sex, race, and gender – were found to significantly influence vaccine acceptance, receipt and outcomes in this review.