Protective human antibodies against a conserved epitope in pre- and postfusion influenza hemagglutinin.

Phylogenetically and antigenically distinct influenza A and B viruses (IAV and IBV) circulate in human populations, causing widespread morbidity. Antibodies (Abs) that bind epitopes conserved in both IAV and IBV hemagglutinins (HAs) could protect against disease by diverse virus subtypes. Only one reported HA Ab, isolated from a combinatorial display library, protects against both IAV and IBV. Thus, there has been so far no information on the likelihood of finding naturally occurring human Abs that bind HAs of diverse IAV subtypes and IBV lineages. We have now recovered from several unrelated human donors five clonal Abs that bind a conserved epitope preferentially exposed in the postfusion conformation of IAV and IVB HA2. These Abs lack neutralizing activity in vitro but in mice provide strong, IgG subtype-dependent protection against lethal IAV and IBV infections. Strategies to elicit similar Abs routinely might contribute to more effective influenza vaccines.

rAAV expressing a COBRA-designed influenza hemagglutinin generates a protective and durable adaptive immune response with a single dose.

Influenza remains a worldwide public health threat. Although seasonal influenza vaccines are currently the best means of preventing severe disease, the standard-of-care vaccines require frequent updating due to antigenic drift and can have low efficacy, particularly in vulnerable populations. Here, we demonstrate that a single administration of a recombinant adenovirus-associated virus (rAAV) vector expressing a computationally optimized broadly reactive antigen (COBRA)-derived influenza H1 hemagglutinin (HA) induces strongly neutralizing and broadly protective antibodies in naïve mice and ferrets with pre-existing influenza immunity. Following a lethal viral challenge, the rAAV-COBRA vaccine allowed for significantly reduced viral loads in the upper and lower respiratory tracts and complete protection from morbidity and mortality that lasted for at least 5 months post-vaccination. We observed no signs of antibody waning during this study. CpG motif enrichment of the antigen can act as an internal adjuvant to further enhance the immune responses to allow for lower vaccine dosages with the induction of unique interferon-producing CD4+ and CD8+ T cells specific to HA head and stem peptide sequences. Our studies highlight the utility of rAAV as an effective platform to improve seasonal influenza vaccines. IMPORTANCE: Developing an improved seasonal influenza vaccine remains an ambitious goal of researchers and clinicians alike. With influenza routinely causing severe epidemics with the potential to rise to pandemic levels, it is critical to create an effective, broadly protective, and durable vaccine to improve public health worldwide. As a potential solution, we created a rAAV viral vector expressing a COBRA-optimized influenza hemagglutinin antigen with modestly enriched CpG motifs to evoke a robust and long-lasting immune response after a single intramuscular dose without needing boosts or adjuvants. Importantly, the rAAV vaccine boosted antibody breadth to future strains in ferrets with pre-existing influenza immunity. Together, our data support further investigation into the utility of viral vectors as a potential avenue to improve our seasonal influenza vaccines.

Nucleoside-Modified mRNA-Based Influenza Vaccines Circumvent Problems Associated with H3N2 Vaccine Strain Egg Adaptation.

Most human influenza vaccine antigens are produced in fertilized chicken eggs. Recent H3N2 egg-based vaccine antigens have limited effectiveness, partially due to egg-adaptive substitutions that alter the antigenicity of the hemagglutinin (HA) protein. The nucleoside-modified mRNA encapsulated in lipid nanoparticles (mRNA-LNP) vaccine platform is a promising alternative for egg-based influenza vaccines because mRNA-LNP-derived antigens are not subject to adaptive pressures that arise during the production of antigens in chicken eggs. Here, we compared H3N2-specific antibody responses in mice vaccinated with either 3c.2A H3-encoding mRNA-LNP or a conventional egg-based Fluzone vaccine (which included an egg-adapted 3c.2A antigen) supplemented with an MF59-like adjuvant. We tested mRNA-LNP encoding wild-type and egg-adapted H3 antigens. We found that mRNA-LNP encoding wild-type H3 elicited antibodies that neutralized the wild-type 3c.2A H3N2 virus more effectively than antibodies elicited by mRNA-LNP encoding egg-adapted H3 or the egg-based Fluzone vaccine. mRNA-LNP expressing either wild-type or egg-adapted H3 protected mice against infection with the wild-type 3c2.A H3N2, whereas the egg-based Fluzone vaccine did not. We found that both mRNA-LNP vaccines elicited high levels of group 2 HA stalk-reactive antibodies, which likely contributed to protection in vivo. Our studies indicate that nucleoside-modified mRNA-LNP-based vaccines can circumvent problems associated with egg adaptations with recent 3c2.A H3N2 viruses. IMPORTANCE This study shows that the nucleoside-modified mRNA-LNP vaccine platform is a promising alternative for egg-based influenza vaccines. We show that mRNA-LNP vaccines expressing H3 antigens elicit high levels of antibodies in mice and protect against H3N2 influenza virus infection.

Trimeric, APC-Targeted Subunit Vaccines Protect Mice against Seasonal and Pandemic Influenza.

Viral subunit vaccines contain the specific antigen deemed most important for development of protective immune responses. Typically, the chosen antigen is a surface protein involved in cellular entry of the virus, and neutralizing antibodies may prevent this. For influenza, hemagglutinin (HA) is thus a preferred antigen. However, the natural trimeric form of HA is often not considered during subunit vaccine development. Here, we have designed a vaccine format that maintains the trimeric HA conformation while targeting antigen toward major histocompatibility complex class II (MHCII) molecules or chemokine receptors on antigen-presenting cells (APC) for enhanced immunogenicity. Results demonstrated that a single DNA vaccination induced strong antibody and T-cell responses in mice. Importantly, a single DNA vaccination also protected mice from lethal challenges with influenza viruses H1N1 and H5N1. To further evaluate the versatility of the format, we developed MHCII-targeted HA from influenza A/California/04/2009(H1N1) as a protein vaccine and benchmarked this against Pandemrix and Flublok. These vaccine formats are different, but similar immune responses obtained with lower vaccine doses indicated that the MHCII-targeted subunit vaccine has an immunogenicity and efficacy that warrants progression to larger animals and humans. IMPORTANCE Subunit vaccines present only selected viral proteins to the immune system and allow for safe and easy production. Here, we have developed a novel vaccine where influenza hemagglutinin is presented in the natural trimeric form and then steered toward antigen-presenting cells for increased immunogenicity. We demonstrate efficient induction of antibodies and T-cell responses, and demonstrate that the vaccine format can protect mice against influenza subtypes H1N1, H5N1, and H7N1.

Evidence base for yearly respiratory virus vaccines: Current status and proposed improved strategies.

Annual vaccination is widely recommended for influenza and SARS-CoV-2. In this essay, we analyse and question the prevailing policymaking approach to these respiratory virus vaccines, especially in the United States. Every year, licensed influenza vaccines are reformulated to include specific strains expected to dominate in the season ahead. Updated vaccines are rapidly manufactured and approved without further regulatory requirement of clinical data. Novel vaccines (i.e. new products) typically undergo clinical trials, though generally powered for clinically unimportant outcomes (e.g. lab-confirmed infections, regardless of symptomatology or antibody levels). Eventually, the current and future efficacy of influenza and COVID-19 vaccines against hospitalization or death carries considerable uncertainty. The emergence of highly transmissible SARS-CoV-2 variants and waning vaccine-induced immunity led to plummeting vaccine effectiveness, at least against symptomatic infection, and booster doses have since been widely recommended. No further randomized trials were performed for clinically important outcomes for licensed updated boosters. In both cases, annual vaccine effectiveness estimates are generated by observational research, but observational studies are particularly susceptible to confounding and bias. Well-conducted experimental studies, particularly randomized trials, are necessary to address persistent uncertainties about influenza and COVID-19 vaccines. We propose a new research framework which would render results relevant to the current or future respiratory viral seasons. We demonstrate that experimental studies are feasible by adopting a more pragmatic approach and provide strategies on how to do so. When it comes to implementing policies that seriously impact people's lives, require substantial public resources and/or rely on widespread public acceptance, high evidence standards are desirable.

Systematic review of the efficacy, effectiveness and safety of MF59® adjuvanted seasonal influenza vaccines for the prevention of laboratory-confirmed influenza in individuals ≥18 years of age.

The most effective means of preventing seasonal influenza is through vaccination. In this systematic review, we investigated the efficacy, effectiveness and safety of MF59® adjuvanted trivalent and quadrivalent influenza vaccines to prevent laboratory-confirmed influenza. A systematic literature search was conducted in electronic databases and grey literature sources up to 7 February 2020. Randomised controlled trials and non-randomised studies of interventions (NRSIs) were eligible for inclusion. The search returned 28,846 records, of which 48 studies on MF59® adjuvanted vaccines met our inclusion criteria. No efficacy trials were identified. In terms of vaccine effectiveness (VE), MF59® adjuvanted trivalent influenza vaccines were effective in preventing laboratory-confirmed influenza in older adults (aged ≥65 years) compared with no vaccination (VE = 45%, 95% confidence interval (CI) 23%-61%, 5 NRSIs across 3 influenza seasons). By subtype, significant effect was found for influenza A(H1N1) (VE = 61%, 95% CI 44%-73%) and B (VE = 29%, 95% CI 5%-46%), but not for A(H3N2). In terms of relative VE, there was no significant difference comparing MF59® adjuvanted trivalent vaccines with either non-adjuvanted trivalent or quadrivalent vaccines. Compared with traditional trivalent influenza vaccines, MF59® adjuvanted trivalent influenza vaccines were associated with a greater number of local adverse events (RR = 1.90, 95% CI 1.50-2.39) and systemic reactions (RR = 1.18, 95% CI 1.02-1.38). In conclusion, MF59® adjuvanted trivalent influenza vaccines were found to be more effective than 'no vaccination'. Based on limited data, there was no significant difference comparing the effectiveness of MF59® adjuvanted vaccines with their non-adjuvanted counterparts.

Systematic review of the efficacy, effectiveness and safety of high-dose seasonal influenza vaccines for the prevention of laboratory-confirmed influenza in individuals ≥18 years of age.

This review sought to assess the efficacy, effectiveness and safety of high-dose inactivated influenza vaccines (HD-IIV) for the prevention of laboratory-confirmed influenza in individuals aged 18 years or older. A systematic literature search was conducted in electronic databases and grey literature sources up to 7 February 2020. Randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs) were included. The search returned 28,846 records, of which 36 studies were included. HD-IIV was shown to have higher relative vaccine efficacy in preventing influenza compared with standard-dose influenza vaccines (SD-IIV3) in older adults (Vaccine effectiveness (VE) = 24%, 95% CI 10-37, one RCT). One NRSI demonstrated significant effect for HD-IIV3 against influenza B (VE = 89%, 95% CI 47-100), but not for influenza A(H3N2) (VE = 22%, 95% CI -82 to 66) when compared with no vaccination in older adults. HD-IIV3 showed significant relative effect compared with SD-IIV3 for influenza-related hospitalisation (VE = 11.8%, 95% CI 6.4-17.0, two NRSIs), influenza- or pneumonia-related hospitalisation (VE = 13.7%, 95% CI 9.5-17.7, three NRSIs), influenza-related hospital encounters (VE = 13.1%, 95% CI 8.4-17.7, five NRSIs), and influenza-related office visits (VE = 3.5%, 95% CI 1.5-5.5, two NRSIs). For safety, HD-IIV were associated with significantly higher rates of local and systemic adverse events compared with SD-IIV (combined local reactions, pain at injection site, swelling, induration, headache, chills and malaise). From limited data, compared with SD-IIV, HD-IIV were found to be more effective in the prevention of laboratory-confirmed influenza, for a range of proxy outcome measures, and associated with more adverse events.

Association Between Influenza Vaccination and Acute Kidney Injury Among the Elderly: A Self-Controlled Case Series.

BACKGROUND: Several cases of renal complications, including acute kidney injury (AKI), after influenza vaccination have been reported, but the association remains unproven. We evaluated the association between influenza vaccination and AKI occurrence among the Korean elderly in the 2018-2019 and 2019-2020 seasons. METHODS: We used a large database combining vaccination registration data from the Korea Disease Control and Prevention Agency and claims data from the National Health Insurance Service. The study subjects were patients hospitalized with AKI for the first-time following vaccination among those who received one influenza vaccine in the 2018-2019 or 2019-2020 season. Only those aged 65 or older at the date of vaccination were included. We performed a self-controlled case series study, designating the risk period as 1 to 28 days post-vaccination and the observation period as each influenza season. The adjusted incidence rate ratio (aIRR) was calculated by adjusting for nephrotoxic drug use and influenza infection that may influence AKI occurrence using a conditional Poisson regression model. RESULTS: A total of 16 713 and 16 272 AKI events were identified during the 2018-2019 and 2019-2020 seasons, respectively. The aIRR for AKI was 0.83 (95% confidence interval [CI] = 0.79-0.87) in the 2018-2019 season. The aIRR for the 2019-2020 influenza season was similar to the 2018-2019 season (aIRR = 0.86; 95% CI = 0.82-0.90). CONCLUSIONS: Influenza vaccination is associated with a lower risk of AKI in the elderly over 65. This evidence supports the recommendation of annual influenza vaccination for the elderly. Further studies are needed to determine the biological mechanisms linking the influenza vaccine and AKI.

Altered liver function test after Covid-19 vaccines: A retrospective control group study.

BACKGROUND AND PURPOSE: Liver injury after Covid-19 vaccine has been described, although the incidence was not well established. We aimed to compare cumulative incidence of new onset liver test alteration after Covid-19 vaccination, and to compare with an historical control of influenza vaccination. METHODS: We conducted a retrospective cohort study which included adults who received at least one dose of Covid-19 vaccine from January 1 to May 30, 2021 and a control group who received a single dose of influenza vaccine during 2019, in a tertiary medical center from Argentina. RESULTS: We included 29 798 patients in Covid-19 vaccine group and 24 605 in influenza vaccine group. Liver function tests were performed in 7833 (26.9%) in Covid-19 vaccine group and 8459 (34.37%) in influenza vaccine group. Cumulative incidence at 90 days of new onset liver enzyme test alteration was 4.7 per 1000 (95% 4.0-5.5) for Covid-19 group, and 5.1 per 1000 (95% 4.3-6.1) for the influenza vaccine group (p value = 0.489). Two patients in the Covid-19 vaccine group developed immune mediated liver injury. CONCLUSIONS: We found no difference in liver test alteration between groups. These findings support the safety of Covid-19 vaccines. While we have identified two cases that are consistent with immune mediated liver injury following COVID-19 vaccination, we believe that the available data is insufficient to attribute them solely to the vaccination.

Early influenza vaccine effectiveness estimates using routinely collected data, Alberta, Canada, 2023/24 season.

Timely and precise influenza vaccine effectiveness (VE) estimates are needed to guide public health messaging and impact vaccine uptake immediately. Using routinely collected laboratory, vaccination and health administrative data from Alberta, Canada, we estimated influenza VE against infection for the 2023/24 season on a near real-time basis, to late December, at 61% (95% CI: 58-64) against influenza A(H1N1), 49% (95% CI: 28-63) against influenza A(H3N2) and 75% (95% CI: 58-85) against influenza B.

Avian Influenza Virus A(H5Nx) and Prepandemic Candidate Vaccines: State of the Art.

Avian influenza virus has been long considered the main threat for a future pandemic. Among the possible avian influenza virus subtypes, A(H5N1) clade 2.3.4.4b is becoming enzootic in mammals, representing an alarming step towards a pandemic. In particular, genotype B3.13 has recently caused an outbreak in US dairy cattle. Since pandemic preparedness is largely based on the availability of prepandemic candidate vaccine viruses, in this review we will summarize the current status of the enzootics, and challenges for H5 vaccine manufacturing and delivery.

Influenza During the 2010-2020 Decade in the United States: Seasonal Outbreaks and Vaccine Interventions.

The 10 years between the last influenza pandemic and start of the severe acute respiratory syndrome coronavirus 2 pandemic have been marked by great advances in our ability to follow influenza occurrence and determine vaccine effectiveness (VE), largely based on widespread use of the polymerase chain reaction assay. We examine the results, focusing mainly on data from the United States and inactivated vaccines. Surveillance has expanded, resulting in increased ability to characterize circulating viruses and their impact. The surveillance has often confirmed previous observations on timing of outbreaks and age groups affected, which can now be examined in greater detail. Selection of strains for vaccines is now based on enhanced viral characterization using immunologic, virologic, and computational techniques not previously available. Vaccine coverage has been largely stable, but VE has remained modest and, in some years, very low. We discuss ways to improve VE based on existing technology while we work toward supraseasonal vaccines.

Effect of Repeat Vaccination on Immunogenicity of Quadrivalent Cell-Culture and Recombinant Influenza Vaccines Among Healthcare Personnel Aged 18-64 Years: A Randomized, Open-Label Trial.

BACKGROUND: Antibody responses to non-egg-based standard-dose cell-culture influenza vaccine (containing 15 µg hemagglutinin [HA]/component) and recombinant vaccine (containing 45 µg HA/component) during consecutive seasons have not been studied in the United States. METHODS: In a randomized trial of immunogenicity of quadrivalent influenza vaccines among healthcare personnel (HCP) aged 18-64 years over 2 consecutive seasons, HCP who received recombinant-HA influenza vaccine (RIV) or cell culture-based inactivated influenza vaccine (ccIIV) during the first season (year 1) were re-randomized the second season of 2019-2020 (year 2 [Y2]) to receive ccIIV or RIV, resulting in 4 ccIIV/RIV combinations. In Y2, hemagglutination inhibition antibody titers against reference cell-grown vaccine viruses were compared in each ccIIV/RIV group with titers among HCP randomized both seasons to receive egg-based, standard-dose inactivated influenza vaccine (IIV) using geometric mean titer (GMT) ratios of Y2 post-vaccination titers. RESULTS: Y2 data from 414 HCP were analyzed per protocol. Compared with 60 IIV/IIV recipients, 74 RIV/RIV and 106 ccIIV/RIV recipients showed significantly elevated GMT ratios (Bonferroni corrected P < .007) against all components except A(H3N2). Post-vaccination GMT ratios for ccIIV/ccIIV and RIV/ccIIV were not significantly elevated compared with IIV/IIV except for RIV/ccIIV against A(H1N1)pdm09. CONCLUSIONS: In adult HCP, receipt of RIV in 2 consecutive seasons or the second season was more immunogenic than consecutive egg-based IIV for 3 of the 4 components of quadrivalent vaccine. Immunogenicity of ccIIV/ccIIV was similar to that of IIV/IIV. Differences in HA antigen content may play a role in immunogenicity of influenza vaccination in consecutive seasons. CLINICAL TRIALS REGISTRATION: NCT03722589.

Differential Recognition of Computationally Optimized H3 Hemagglutinin Influenza Vaccine Candidates by Human Antibodies.

Among circulating influenza viruses in humans, H3N2 viruses typically evolve faster than other subtypes and have caused disease in millions of people since emerging in 1968. Computationally optimized broadly reactive antigen (COBRA) technology is one strategy to broaden vaccine-elicited antibody responses among influenza subtypes. In this study, we determined the structural integrity of an H3N2 COBRA hemagglutinin (HA), TJ5, and we probed the antigenic profile of several H3N2 COBRA HAs by assessing recognition of these immunogens by human B cells from seasonally vaccinated human subjects. Of three recently described COBRA H3 HA antigens (TJ5, NG2, and J4), we determined that TJ5 and J4 HA proteins recognize pre-existing B cells more effectively than NG2 HA and a wild-type Hong Kong/4801/2014 protein. We also isolated a panel of 12 H3 HA-specific human monoclonal antibodies (MAbs) and identified that most MAbs recognize both wild-type and COBRA HA proteins and have functional activity against a broad panel of H3N2 viruses. Most MAbs target the receptor-binding site, and one MAb targets the HA stem. MAb TJ5-5 recognizes TJ5 and J4 COBRA HA proteins but has poor recognition of NG2 HA, similar to the global B-cell analysis. We determined a 3.4 Å structure via cryo-electron microscopy of Fab TJ5-5 complexed with the H3 COBRA TJ5, which revealed residues important to the differential binding. Overall, these studies determined that COBRA H3 HA proteins have correct antigenic and structural features, and the proteins are recognized by B cells and MAbs isolated from seasonally vaccinated humans. IMPORTANCE Vaccine development for circulating influenza viruses, particularly for the H3N2 subtype, remains challenging due to consistent antigenic drift. Computationally optimized broadly reactive antigen (COBRA) technology has proven effective for broadening influenza hemagglutinin (HA)-elicited antibody responses compared to wild-type immunogens. Here, we determined the structural features and antigenic profiles of H3 COBRA HA proteins. Two H3 COBRA HA proteins, TJ5 and J4, are better recognized by pre-existing B cells and monoclonal antibodies from the 2017 to 2018 vaccine season compared to COBRA NG2 and a wild-type A/Hong Kong/2014 HA protein. We determined a cryo-electron microscopy (cryo-EM) structure of one MAb that poorly recognizes NG2, MAb TJ5-5, in complex with the TJ5 COBRA HA protein and identified residues critical to MAb recognition. As NG2 is more effective than TJ5 for the recent Hong Kong/2019 virus, these data provide insights into the diminished effectiveness of influenza vaccines across vaccine seasons.

A Virion-Based Combination Vaccine Protects against Influenza and SARS-CoV-2 Disease in Mice.

Vaccines targeting SARS-CoV-2 have been shown to be highly effective; however, the breadth against emerging variants and the longevity of protection remains unclear. Postimmunization boosting has been shown to be beneficial for disease protection, and as new variants continue to emerge, periodic (and perhaps annual) vaccination will likely be recommended. New seasonal influenza virus vaccines currently need to be developed every year due to continual antigenic drift, an undertaking made possible by a robust global vaccine production and distribution infrastructure. To create a seasonal combination vaccine targeting both influenza viruses and SARS-CoV-2 that is also amenable to frequent reformulation, we have developed an influenza A virus (IAV) genetic platform that allows the incorporation of an immunogenic domain of the SARS-CoV-2 spike (S) protein onto IAV particles. Vaccination with this combination vaccine elicited neutralizing antibodies and provided protection from lethal challenge with both pathogens in mice. This approach may allow the leveraging of established influenza vaccine infrastructure to generate a cost-effective and scalable seasonal vaccine solution for both influenza and coronaviruses. IMPORTANCE The rapid emergence of SARS-CoV-2 variants since the onset of the pandemic has highlighted the need for both periodic vaccination "boosts" and a platform that can be rapidly reformulated to manufacture new vaccines. In this work, we report an approach that can utilize current influenza vaccine manufacturing infrastructure to generate combination vaccines capable of protecting from both influenza virus- and SARS-CoV-2-induced disease. The production of a combined influenza/SARS-CoV-2 vaccine may represent a practical solution to boost immunity to these important respiratory viruses without the increased cost and administration burden of multiple independent vaccines.

Vaccine Attitudes and COVID-19 Vaccine Intention Among Parents of Children With Kidney Disease or Primary Hypertension.

RATIONALE & OBJECTIVE: Children with kidney disease and primary hypertension may be more vulnerable to COVID-19. We examined COVID-19 vaccine hesitancy among parents of children with chronic kidney disease or hypertension. STUDY DESIGN: Sequential explanatory mixed-methods design; survey followed by in-depth interviews. SETTING & PARTICIPANTS: Parents of children aged <18 years with kidney disease or primary hypertension within a large pediatric practice. EXPOSURE: Parental attitudes toward general childhood and influenza vaccines assessed by the Vaccine Hesitancy Scale. Kidney disease classification, demographic and socioeconomic factors, experiences with COVID-19, COVID-19 mitigation activities and self-efficacy, and sources of vaccine information. OUTCOME: Willingness to vaccinate child against COVID-19. ANALYTICAL APPROACH: Analysis of variance (ANOVA) test to compare parental attitudes toward general childhood and influenza vaccination with attitudes toward COVID-19 vaccination. Multinomial logistic regression to assess predictors of willingness to vaccinate against COVID-19. Thematic analysis of interview data to characterize influences on parental attitudes. RESULTS: Of the participants, 207 parents completed the survey (39% of approached): 75 (36%) were willing, 80 (39%) unsure, and 52 (25%) unwilling to vaccinate their child against COVID-19. Hesitancy toward general childhood and influenza vaccines was highest among the unwilling group (P < 0.001). More highly educated parents more likely to be willing to vaccinate their children, while Black race was associated with being more likely to be unwilling. Rushed COVID-19 vaccine development as well as fear of serious and unknown long-term side effects were themes that differed across the parental groups that were willing, unsure, or unwilling to vaccinate their children. Although doctors and health care teams are trusted sources of vaccine information, perceptions of benefit versus harm and experiences with doctors differed among these 3 groups. The need for additional information on COVID-19 vaccines was greatest among those unwilling or unsure about vaccinating. LIMITATIONS: Generalizability may be limited. CONCLUSIONS: Two-thirds of parents of children with kidney disease or hypertension were unsure or unwilling to vaccinate their child against COVID-19. Higher hesitancy toward routine childhood and influenza vaccination was associated with hesitancy toward COVID-19 vaccines. Enhanced communication of vaccine information relevant to kidney patients in an accessible manner should be examined as a means to reduce vaccine hesitancy. PLAIN-LANGUAGE SUMMARY: Children with kidney disease or hypertension may do worse with COVID-19. As there are now effective vaccines to protect children from COVID-19, we wanted to find out what parents think about COVID-19 vaccines and what influences their attitudes. We surveyed and then interviewed parents of children who had received a kidney transplant, were receiving maintenance dialysis, had chronic kidney disease, or had hypertension. We found that two-thirds of parents were hesitant to vaccinate their children. Their reasons varied, but the key issues included the need for information pertinent to their child and a consistent message from doctors and other health care providers. These findings may inform an effective vaccine campaign to protect children with kidney disease and hypertension.

Challenges encountered during the systematic review of newer and enhanced influenza vaccines and recommendations for the future.

There are a variety of challenges in the conduct of systematic reviews of influenza vaccines. We describe our experience of completing four systematic reviews of newer and enhanced inactivated seasonal influenza vaccines. The reporting of the included studies created significant challenges for study identification, data extraction and analysis. Those challenges have implications for the resources required to conduct reviews and, more significantly, for the accuracy of the estimated treatment effect. There is a substantial burden of morbidity and mortality associated with seasonal influenza, and the evidence used to support vaccination strategies requires regular review. An improved review process will facilitate robust decision-making both nationally and internationally. We recommend the development of reporting guidelines, increased engagement between researchers and decision makers, a database of identified trials, and research into search optimisation.

Influenza vaccine uptake among children and older adults in China: a secondary analysis of a quasi-experimental study.

BACKGROUND: Influenza vaccination is the key to prevent influenza-related disease, especially among high-risk populations. However, influenza vaccine uptake in China is low. This secondary analysis of a quasi-experimental trial aimed to understand factors associated with influenza vaccine uptake among children and older people stratified by funding context. METHODS: A total of 225 children (aged 0.5-8 years) and 225 older people (aged 60 years or above) were recruited from three clinics (rural, suburban and urban) in Guangdong Province. Participants were allocated into two groups based on funding contexts: a self-paid group (N = 150, 75 children and 75 older adults) in which participants paid full price for their vaccination; and a subsidized group (N = 300, 150 children and 150 older adults) in which varying levels of financial support was provided. Univariate and multivariable logistic regressions were conducted stratified by funding contexts. RESULTS: Overall, 75.0% (225/300) of participants in the subsidized group and 36.7% (55/150) in the self-paid group got vaccinated. Older adults had lower vaccination rates than children in both funding groups, while both age groups showed much higher uptake in the subsidized group than in the self-paid group (aOR = 5.96, 95% CI: 3.77-9.42, p = 0.001). In the self-paid group, having prior influenza vaccination history of children (aOR:2.61, 95%CI: 1.06-6.42) or older people (aOR:4.76, 95%CI: 1.08-20.90) was associated with increased influenza vaccine uptake compared to those who had no prior vaccination experiences in the family. While in the subsidized group, participants who got married or lived with partners (aOR = 0.32, 0.10-0.98) had lower vaccination uptake than single ones. Trust in providers' advice (aOR = 4.95, 95%CI:1.99, 12.43), perceived effectiveness of the vaccine (aOR: 12.18, 95%CI: 5.21-28.50), and experienced influenza-like illnesses in the family in the past year (aOR = 46.52, 4.10, 533.78) were associated with higher vaccine uptake. CONCLUSIONS: Older people had suboptimal vaccine uptake compared to children in both contexts and need more attention to enhance influenza vaccination. Tailoring interventions to different vaccine funding contexts may help improve influenza vaccination: In self-paid context, motivating people to accept their first ever influenza vaccination may be a promising strategy. In subsidized context, improving public confidence in vaccine effectiveness and providers' advice would be useful.

Acceptance of vaccination against pertussis, COVID-19 and influenza during pregnancy: a cross-sectional study.

BACKGROUND: This study aims to assess the uptake of maternal pertussis and COVID-19 vaccination and the intention towards accepting the maternal influenza vaccination. Insights into different socio-demographic factors related to maternal vaccination coverage might help to address vaccine acceptance and improve maternal vaccine uptake in the future. METHODS: We conducted a cross-sectional survey among pregnant women and recent mothers, up to 6 months post-partum. The primary outcome measures of this study were behaviour for maternal pertussis and COVID-19 vaccination, and maternal influenza vaccination intention. Associations between socio-demographic factors and maternal pertussis vaccination and maternal COVID-19 vaccination behaviour; and socio-demographic factors and maternal influenza vaccination intention were assessed using binary logistic regression analyses. RESULTS: In total 1361 respondents filled out the questionnaire. Almost all women (95%) were vaccinated against pertussis during pregnancy, while almost two-third were vaccinated against COVID-19 during pregnancy (58%) and almost one-third (28%) had a positive intention towards receiving the maternal influenza vaccination. Results show that young maternal age and low education level were associated with lower maternal vaccination acceptance. CONCLUSION: Vaccination campaigns focusing on the severity of diseases that are prevented, are needed to increase maternal vaccine acceptance in younger and low-educated pregnant women. We expect that differences in vaccination coverage between the three maternal vaccinations might partly be explained by existing recommendations, campaigns and whether the vaccination is part of the national immunisation program.

[Evaluation of a community-based intervention to increase influenza vaccination coverage in pregnant women]. / Evaluación de una intervención comunitaria para incrementar la cobertura vacunal de la gripe en mujeres embarazadas.

OBJECTIVE: To know the impact of the educational intervention carried out on the professionals of a basic health area and their community participation group, which make up the intervention group (IG), and to analyze its repercussion on the vaccination coverage achieved for influenza in the risk group (pregnant and puerperal women) comparing it with its neighboring basic zone, which makes up the control group (CG), during the 2019/20 vaccination season. DESIGN: Quasi-experimental study of community intervention. SITE: Two basic health zones belonging to the Elche-Crevillente health department, Spain. PARTICIPANTS: Pregnant and postpartum women from 2 basic health areas and the community participation group. Health professionals directly related to the flu vaccination campaign. INTERVENTIONS: Training session for the IG prior to the 2019/20 flu campaign. MAIN MEASUREMENTS: Attitudes towards influenza vaccination in health professionals through the validated CAPSVA questionnaire and the vaccination coverage of pregnant and postpartum women through the Nominal Vaccine Registry and their acceptance of the vaccine in the midwife's office. RESULTS: The influenza vaccination coverage data recorded in Nominal Vaccine Registry for pregnant and puerperal women was 26.4% (n=207) in the IG and 19.7% (n=144) in the CG (p=0.001), with an incidence ratio of 1.34, thus achieving 34% more vaccination in the IG. Acceptance for vaccination in the midwife's office was also high, with 96.5% immunization in IG vs. 89.0% in CG, with a RR=1.09 (95% CI 1.01-1.62). CONCLUSIONS: Joint training strategies for professionals and community assets improve the results of vaccination coverage.