Prevention Of Influenza Virus Infection Research Articles

Preventing Influenza Virus Infection and Severe Influenza Among Pregnant People and Infants.

The landscape of research on the benefits of influenza vaccines and antivirals to protect pregnant persons and infants has increased in recent years, while influenza vaccination rates and antiviral usage have declined. Pregnant people and infants <6 months of age are at increased risk of hospitalization with influenza, making protection of this population essential. Maternal influenza vaccination at any time during pregnancy is the best way to reduce the risk of influenza and severe influenza in both pregnant people and their infants <6 months of age. Influenza antiviral medications for pregnant people and infants are also recommended as early as possible if influenza is confirmed or suspected. This report will update on the current research on the benefits of influenza vaccination during pregnancy and influenza antiviral medication for the pregnant person and infant, current Advisory Committee on Immunization Practices recommendations for influenza vaccination in pregnancy and vaccination coverage rates, current influenza antiviral medication guidance and usage rates in pregnancy and among infants, and future directions for influenza pregnancy research. With over half a century of maternal influenza vaccination in the United States, we have improved protection for pregnant persons and infants against influenza, but we still have room for improvement and optimization with new challenges to overcome following the COVID-19 pandemic. By continuing to fill research gaps and increase vaccination coverage and antiviral usage, there is potential for significant reductions in the domestic and global burden of influenza in pregnant persons and infants.

Astragalus Polysaccharide improves immunogenicity of influenza vaccine as well as modulate gut microbiota in BALB/c mice

BackgroundVaccination is the best way to prevent influenza virus infection, and insufficient antibodies make it difficult to resist influenza virus invasion. Astragalus Polysaccharide (APS) has a boosting effect on immunity, so we evaluate the effect of APS as an immune adjuvant for H1N1 influenza vaccines in this study. MethodsThe mice were immunized twice with influenza A (H1N1) vaccine and APS. Subsequently, the serum antibody levels were assessed using enzyme-linked immunosorbent assay (ELISA). The frequency of peripheral immune T cells was determined by flow cytometry. Following this, the immunized mice were exposed to a lethal dose of the virus, and changes in body weight and survival rates were recorded. Hematoxylin-eosin staining was employed to observe pathological alterations in lung and intestinal tissues. Western blot analysis was conducted to detect the expression of intestinal barrier function proteins (Occludin and Claudin-1). ELISA was utilized to measure the expression level of serum inflammatory cytokine TNF-α. Fresh mouse feces were collected after the initial immunization as well as after viral infection for 16S rRNA analysis aimed at detecting alterations in gut microbiota. ResultsCompared to the Hemagglutinin (HA) group, the APS group demonstrated higher levels of immunoglobulin G (IgG), IgG1, and IgG3, as well as neutralizing antibody levels. Additionally, it increased the frequency of CD8+ cells to enhance resistance against lethal infection. On day 14 post-infection, the high-dose APS group exhibited a higher survival rate (71.40 %) compared to the HA group (14.28 %), along with faster weight recovery. Furthermore, APS was found to ameliorate alveolar damage in lung tissue and rectify intestinal structural disorder. It also upregulated the expression levels of tight junction proteins Occludin and Claudin-1 in intestinal tissue while reducing serum TNF-α expression levels. In addition, populations of Colidextribacter, Peptococcaceae, and Ruminococcaceae were the dominant gut microbiota in the APS group after viral infection. ConclusionAPS has an immune-enhancing effect and is expected to be a novel adjuvant in the H1N1 influenza vaccine.

Recommendations for Prevention and Control of Influenza in Children, 2024-2025: Policy Statement.

This statement updates the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccines and antiviral medications in the prevention and treatment of influenza in children during the 2024-2025 influenza season. A detailed review of the evidence supporting these recommendations is published in the accompanying technical report (www.pediatrics.org/cgi/doi/10.1542/peds.2024-068508). The American Academy of Pediatrics recommends annual influenza vaccination of all children without medical contraindications starting at 6 months of age. Children are at risk for hospitalization and death from influenza. Influenza vaccination is an important strategy for protecting children and the broader community as well as reducing the overall burden of respiratory illnesses when other viruses are cocirculating. Any licensed influenza vaccine appropriate for age and health status can be administered, ideally as soon as possible in the season, without preference for one product or formulation over another. All licensed influenza vaccines for use in the United States are trivalent for the 2024-2025 influenza season. Antiviral treatment of influenza is recommended for children with suspected (eg, influenza-like illness [fever with either cough or sore throat]) or confirmed influenza who are hospitalized or have severe or progressive disease or have underlying conditions that increase their risk of complications of influenza, regardless of duration of illness. Antiviral treatment should be initiated as soon as possible. Antiviral treatment may be considered in the outpatient setting for symptomatic children who are not at high risk for influenza complications with suspected or confirmed influenza disease, if treatment can be initiated within 48 hours of illness onset. Antiviral treatment may also be considered for children with suspected or confirmed influenza disease whose siblings or household contacts either are younger than 6 months or have a high-risk condition that predisposes them to complications of influenza. Antiviral chemoprophylaxis is recommended for the prevention of influenza virus infection as an adjunct to vaccination in certain individuals, especially exposed children who are asymptomatic and are at high risk for influenza complications but have not yet been immunized or those who are not expected to mount an effective immune response.

Orally dissolving film as a potential vaccine delivery carrier to prevent influenza virus infection

Orally dissolving films (ODF) are designed to be dissolved on the tongue and absorbed in the mouth. It offers multiple advantages over the commonly used needle-based vaccines, especially in terms of convenience allowing safe, painless, and easy self-administration. As the efficacy of ODF-encapsulated influenza vaccines has not been demonstrated, we assessed the protection elicited by inactivated influenza virus (A/PR/8/34, H1N1) vaccine delivered using ODFs in mice. Trehalose and pullulan components of the ODF ensured that the HA antigens of the inactivated PR8 virus retained their stability while ensuring the rapid release of the vaccines upon exposure to murine saliva. Mice were immunized thrice by placing the PR8-ODF on the tongues of mice at 4-week intervals, and vaccine-induced protection was evaluated upon lethal homologous challenge infection. The PR8-ODF vaccination elicited virus-specific serum IgG and IgA antibody responses, hemagglutinin inhibition (HAI), and viral neutralization. Upon challenge infection, ODF vaccination showed higher levels of IgG and IgA antibody responses in the lungs and antibody-secreting cell (ASC) responses in both lung and spleen compared to unimmunized controls. These results corresponded with the enhanced T cell and germinal center B cell responses in the lungs and spleens. Importantly, ODF vaccination significantly reduced lung virus titers and inflammatory cytokines (IFN-γ, IL-6) production compared to unvaccinated control. ODF vaccination ensured 100% survival and prevented weight loss in mice. These findings suggest that influenza vaccine delivery through ODFs could be a promising approach for oral vaccine development.

Dual neutralization of influenza virus hemagglutinin and neuraminidase by a bispecific antibody leads to improved antiviral activity

Targeting multiple viral proteins is pivotal for sustained suppression of highly mutable viruses. In recent years, broadly neutralizing antibodies that target the influenza virus hemagglutinin and neuraminidase glycoproteins have been developed, and antibody monotherapy has been tested in preclinical and clinical studies to treat or prevent influenza virus infection. However, the impact of dual neutralization of the hemagglutinin and neuraminidase on the course of infection, as well as its therapeutic potential, has not been thoroughly tested. For this purpose, we generated a bispecific antibody that neutralizes both the hemagglutinin and the neuraminidase of influenza viruses. We demonstrated that this bispecific antibody has a dual antiviral activity as it blocks infection and prevents the release of progeny viruses from the infected cells. We show that dual neutralization of the hemagglutinin and the neuraminidase by a bispecific antibody is advantageous over monoclonal antibody combination as it resulted an improved neutralization capacity and augmented the antibody effector functions. Notably, the bispecific antibody showed enhanced antiviral activity in influenza virus-infected mice, reduced mice mortality and limited the virus mutation profile upon antibody administration. Thus, dual neutralization of the hemagglutinin and neuraminidase could be effective in controlling influenza virus infection.

Leveraging baseline transcriptional features and information from single-cell data to power the prediction of influenza vaccine response.

Vaccination is still the primary means for preventing influenza virus infection, but the protective effects vary greatly among individuals. Identifying individuals at risk of low response to influenza vaccination is important. This study aimed to explore improved strategies for constructing predictive models of influenza vaccine response using gene expression data. We first used gene expression and immune response data from the Immune Signatures Data Resource (IS2) to define influenza vaccine response-related transcriptional expression and alteration features at different time points across vaccination via differential expression analysis. Then, we mapped these features to single-cell resolution using additional published single-cell data to investigate the possible mechanism. Finally, we explored the potential of these identified transcriptional features in predicting influenza vaccine response. We used several modeling strategies and also attempted to leverage the information from single-cell RNA sequencing (scRNA-seq) data to optimize the predictive models. The results showed that models based on genes showing differential expression (DEGs) or fold change (DFGs) at day 7 post-vaccination performed the best in internal validation, while models based on DFGs had a better performance in external validation than those based on DEGs. In addition, incorporating baseline predictors could improve the performance of models based on days 1-3, while the model based on the expression profile of plasma cells deconvoluted from the model that used DEGs at day 7 as predictors showed an improved performance in external validation. Our study emphasizes the value of using combination modeling strategy and leveraging information from single-cell levels in constructing influenza vaccine response predictive models.

Influenza virus evolution and vaccine development

Although the effectiveness of universal influenza vaccines may vary from year to year, getting vaccinated against the influenza virus remains the optimal strategy for preventing influenza virus infection. As a result, recent research has focused on improving the protective efficacy and potency of influenza vaccines. This paper explores two theories: antigenic drift and antigenic imprinting. Antigenic drift refers to the gradual changes and evolution of antigens within influenza viruses. However, epidemiological data suggest that a single strain dominates each flu season. The theory of antigenic imprinting helps explain this phenomenon. Population immunity targets epitopes of limited variables (ELVs). Influenza vaccines can target ELVs to enhance vaccine effectiveness specifically.

Influenza vaccination mitigates severe complications in hospitalized patients: A ten-year observational study, Spain, 2009-2019

Influenza epidemics annually impact a substantial portion of adults worldwide, leading to numerous hospitalizations and fatalities. While the primary goal of vaccination is to prevent influenza virus infection, breakthrough infections can still occur despite vaccination. Evaluating the vaccine effectiveness in preventing severe cases among hospitalized patients is crucial for enhancing vaccination strategies. This single-center, observational, cross-sectional, and retrospective study analyzed data from 1,357 patients admitted to La Paz University Hospital for influenza infection between 2009 and 2019. Patients' demographics, clinical variables, comorbidities, vaccination status, and influenza-related outcomes were assessed. Logistic regression analysis was performed to determine the vaccine-independent protective effects. Influenza vaccination independently prevented severe complications, including pneumonia, bacterial superinfection, acute respiratory distress syndrome, and multiple organ failure in hospitalized patients (odds ratio=0.61, 95% confidence interval: 0.47-0.76). Vaccinated patients had significantly lower intensive care unit admission rates (odds ratio=0.42, 95% confidence interval: 0.18-0.92). However, there were no significant differences in mortality rates between vaccinated and unvaccinated patients (P=.385). Our study provides robust evidence supporting the influenza vaccine protective effect against severe outcomes in hospitalized patients during epidemic flu. Vaccination is associated with a significant reduction in severe complications and intensive care unit admissions, emphasizing its importance as a preventive measure. Improving vaccination coverage, especially in specific comorbidities and age groups, could further enhance the vaccine effectiveness in preventing severe influenza cases.

Characterization of non-neutralizing human monoclonal antibodies that target the M1 and NP of influenza A viruses.

Currently, many groups are focusing on isolating both neutralizing and non-neutralizing antibodies to the mutation-prone hemagglutinin as a tool to treat or prevent influenza virus infection. Less is known about the level of protection induced by non-neutralizing antibodies that target conserved internal influenza virus proteins. Such non-neutralizing antibodies could provide an alternative pathway to induce broad cross-reactive protection against multiple influenza virus serotypes and subtypes by partially overcoming influenza virus escape mediated by antigenic drift and shift. Accordingly, more information about the level of protection and potential mechanism(s) of action of non-neutralizing antibodies targeting internal influenza virus proteins could be useful for the design of broadly protective and universal influenza virus vaccines.

Recommendations for Prevention and Control of Influenza in Children, 2023-2024.

This statement updates the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2023-2024 influenza season. A detailed review of the evidence supporting these recommendations is published in the accompanying technical report (www.pediatrics.org/cgi/doi/10.1542/peds.2023-063773). The American Academy of Pediatrics recommends annual influenza vaccination of all children without medical contraindications starting at 6 months of age. Children are at risk for hospitalization and death from influenza. Influenza vaccination is an important strategy for protecting children and the broader community, as well as reducing the overall burden of respiratory illnesses when other viruses are cocirculating. Any licensed influenza vaccine appropriate for age and health status can be administered, ideally as soon as possible in the season, without preference for one product or formulation over another. Antiviral treatment of influenza is recommended for children with suspected (eg, influenza-like illness [fever with either cough or sore throat]) or confirmed influenza who are hospitalized, have severe or progressive disease, or have underlying conditions that increase their risk of complications of influenza, regardless of duration of illness. Antiviral treatment should be initiated as soon as possible. Antiviral treatment may be considered in the outpatient setting for symptomatic children with suspected or confirmed influenza disease who are not at high risk for influenza complications, if treatment can be initiated within 48 hours of illness onset. Antiviral treatment may also be considered for children with suspected or confirmed influenza disease whose siblings or household contacts either are younger than 6 months or have a high-risk condition that predisposes them to complications of influenza. Antiviral chemoprophylaxis is recommended for the prevention of influenza virus infection as an adjunct to vaccination in certain individuals, especially exposed children who are at high risk for influenza complications but have not yet been immunized or those who are not expected to mount an effective immune response.

Progress in research of influenza vaccination in pregnant women

Influenza is an acute respiratory infectious disease caused by influenza virus. Pregnancy is associated with physiologic and immunological changes that may increase the risk for influenza virus infection and influenza-related complications. Influenza vaccination is the most effective way to prevent influenza virus infection. WHO and many countries have classified pregnant women as a priority population for influenza vaccination, however, there are still many challenges for promoting influenza vaccination in pregnant women in China, influenza vaccination coverage in pregnant women remains low and some influenza vaccine package inserts list pregnancy as an absolute contraindication. In this paper, we summarize the research progress in the effects of influenza infection and influenza vaccination during pregnancy both at home and abroad, then discuss the strategies to promote influenza vaccination in pregnancy for the purpose of providing reference for the related research and policy development in China.

Change from low to out-of-season epidemics of influenza in China during the COVID-19 pandemic: A time series study.

Nonpharmaceutical interventions to limit the coronavirus disease 2019 (COVID-19) pandemic might reduce the transmission of influenza viruses and disrupt the typical seasonality of influenza. However, changes in epidemiology and seasonal patterns of influenza remain unknown in China during the COVID-19 pandemic. Data on influenza-like illness (ILI) and influenza cases between surveillance Week 14 in 2010 and Week 6 in 2023 and ILI outbreaks between Week 14 in 2013 and Week 6 in 2023 were collected from the weekly reports of the Chinese National Influenza Center. A total of 32 10 735 ILI specimens were tested between Week 14 in 2010 and Week 6 in 2023 in China, with 12.4% of specimens positive for influenza. The influenza-positive percentage ranged from 11.8% to 21.1% in southern China and 9.5% to 19.5% in northern China between the 2010/2011 and 2019/2020 influenza seasons. The influenza-positive percentage was 0.7% in southern China and 0.2% in northern China in the 2020/2021 season. An increasing trend in influenza-positive percentage was observed in southern China in Weeks 18-27 in the 2022/2023 season, with a peak of 37.3%. A total of 768 ILI outbreaks reported in southern China in Weeks 14-26 in the 2022/2023 season were much more than those in the same period in the 2020/2021 and 2021/2022 seasons. In summary, seasonal influenza shifted from low to out-of-season epidemics during the COVID-19 pandemic in China, especially in southern China. Influenza vaccination and everyday preventive actions, such as mask wearing, appropriate air exchange, and good hand hygiene practices, are essential for the prevention of influenza virus infection during the COVID-19 pandemic.

Obesity Is Associated with an Impaired Baseline Repertoire of Anti-Influenza Virus Antibodies.

Obesity is a risk factor for severe disease and mortality for both influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. While previous studies show that individuals with obesity generate antibody responses following influenza vaccination, infection rates within the obese group were twice as high as those in the healthy-weight group. The repertoire of antibodies raised against influenza viruses following previous vaccinations and/or natural exposures is referred to here as baseline immune history (BIH). To investigate the hypothesis that obesity impacts immune memory to infections and vaccines, we profiled the BIH of obese and healthy-weight adults vaccinated with the 2010-2011 seasonal influenza vaccine in response to conformational and linear antigens. Despite the extensive heterogeneity of the BIH profiles in both groups, there were striking differences between obese and healthy subjects, especially with regard to A/H1N1 strains and the 2009 pandemic virus (Cal09). Individuals with obesity had lower IgG and IgA magnitude and breadth for a panel of A/H1N1 whole viruses and hemagglutinin proteins from 1933 to 2009 but increased IgG magnitude and breadth for linear peptides from the Cal09 H1 and N1 proteins. Age was also associated with A/H1N1 BIH, with young individuals with obesity being more likely to have reduced A/H1N1 BIH. We found that individuals with low IgG BIH had significantly lower neutralizing antibody titers than individuals with high IgG BIH. Taken together, our findings suggest that increased susceptibility of obese participants to influenza infection may be mediated in part by obesity-associated differences in the memory B-cell repertoire, which cannot be ameliorated by current seasonal vaccination regimens. Overall, these data have vital implications for the next generation of influenza virus and SARS-CoV-2 vaccines. IMPORTANCE Obesity is associated with increased morbidity and mortality from influenza and SARS-CoV-2 infection. While vaccination is the most effective strategy for preventing influenza virus infection, our previous studies showed that influenza vaccines fail to provide optimal protection in obese individuals despite reaching canonical correlates of protection. Here, we show that obesity may impair immune history in humans and cannot be overcome by seasonal vaccination, especially in younger individuals with decreased lifetime exposure to infections and seasonal vaccines. Low baseline immune history is associated with decreased protective antibody responses. Obesity potentially handicaps overall responses to vaccination, biasing it toward responses to linear epitopes, which may reduce protective capacity. Taken together, our data suggest that young obese individuals are at an increased risk of reduced protection by vaccination, likely due to altered immune history biased toward nonprotective antibody responses. Given the worldwide obesity epidemic coupled with seasonal respiratory virus infections and the inevitable next pandemic, it is imperative that we understand and improve vaccine efficacy in this high-risk population. The design, development, and usage of vaccines for and in obese individuals may need critical evaluation, and immune history should be considered an alternate correlate of protection in future vaccine clinical trials.

Potential probiotics for regulation of the gut-lung axis to prevent or alleviate influenza in vulnerable populations.

Influenza, also known as "flu", is an infectious disease caused by influenza viruses. Three types of influenza virus, A, B, and C, are able to infect humans. In most people, influenza causes mild symptoms, but it can also induce severe complications and death. Annual influenza vaccines are currently the main intervention used to minimize mortality and morbidity. However, vaccination frequently fails to provide adequate protection, especially in the elderly. Traditional flu vaccine targets hemagglutinin to prevent virus infection, but the constant mutation of hemagglutinin means that it is a challenge to develop vaccines quickly enough to keep up with mutations. Thus, other methods of curbing influenza incidence would be welcomed, especially for vulnerable populations. Although influenza viruses primarily infect the respiratory tract, influenza virus infection also induces intestinal dysbiosis. Through gut microbiota-derived secreted products and the circulating immune cells, gut microbiota can affect pulmonary immunity. The crosstalk between the respiratory tract and gut microbiota, termed the "gut-lung axis", is observed in the regulation of immune responses against influenza virus infection or inflammation-induced lung damage, indicating the possibility of using probiotics to prevent influenza virus infection or alleviate respiratory symptoms. In this review, we summarize the current findings on the antiviral functions of particular probiotics and/or combinations and discuss the antiviral mechanisms and immunomodulatory activities of probiotics invitro, in mice, and in humans. Clinical studies show probiotic supplements can provide health benefits, not only to the elderly or children with compromised immune systems, but also to young- and middle-aged adults.

Vaccine or Garlic-Is It a Choice? Awareness of Medical Personnel on Prevention of Influenza Infections.

Preventing the spread of the influenza virus is one of the primary health policy challenges of many countries worldwide. One of the more effective ways to prevent infection is influenza vaccination, and the people who enjoy the most public confidence in preventive health care are health workers (HWs). For this reason, it is crucial to study the attitudes of HWs toward influenza vaccination. The survey was conducted among 950 medical (physicians and nurses) and administrative staff in three academic hospitals. Respondents to the survey were selected on a random-target basis to represent hospital employees in the study best. The survey was conducted using the PAPI method between August and September 2020. Respondents considered hand washing (52.8%) and avoiding contact with sick people (49.3%) the most effective ways to prevent influenza infection. Three in ten respondents considered wearing a protective mask (30.1%) and getting vaccinated against influenza (29.9%) is fully effective in preventing influenza. Influenza vaccination as effective in preventing influenza virus infection was chosen more often by those who worked in a pediatric hospital. Nurses were twice less likely than physicians to declare that influenza vaccination prevents infection (42.4% for nurses vs. 84.0% for physicians). At the same time, 20.4% of nurses believed that eating garlic effectively prevented influenza infection, and 28.1% declared daily vitamin C helpful. The study pointed to significant educational gaps regarding the role and effectiveness of influenza vaccination in the process of influenza virus infection and indicated a firm belief in medical myths, especially in the nursing community, related to protection against influenza virus infection.

A replication-deficient H9N2 influenza virus carrying H5 hemagglutinin conferred protection against H9N2 and H5N1 influenza viruses in mice

H5N1 and H9N2 influenza viruses have been reported to cause human infections and are believed to have pandemic potential. The vaccine is an effective tool to prevent influenza virus infection. However, inactivated influenza vaccines sometimes result in low antigenicity as result leads to generating of incomplete immune protection in the form of low cellular and humoral immunity. While the low temperature adapted, traditional live attenuated influenza vaccine (LAIV) is associated with the potential risk to revert to a virulent phenotype, there appears an essential need for an alternative potent methodology to design and develop influenza vaccines with substantial safety and efficacy which may confer solid protection against H9N2 or H5N1 influenza virus infections. In the present study, a replication-deficient recombinant influenza virus, WM01ma-HA(H5), expressing hemagglutinin (HA) of both H9N2 and H5N1 subtypes was developed. The chimeric gene segment expressing HA(H5), was designed using the sequence of an open reading frame (ORF) of HA adopted from A/wild duck/Hunan/021/2005(H5N1)(HN021ma) which was flanked by the NA packaging signals of mouse-adapted strain A/Mink/Shandong/WM01/2014(H9N2)(WM01ma). Due to the absence of ORF of structural protein NA, the replication of this engineered H9N2 influenza viruses WM01ma-HA(H5) was hampered in vitro and in vivo but was well competent in MDCK cells stably expressing the NA protein of WM01ma. Intranasal vaccination of mice with WM01ma-HA(H5) stimulated robust immune response without any clinical signs and conferred complete protection from infection by H5N1 or H9N2 subtype influenza viruses.

Global influenza vaccination rates and factors associated with influenza vaccination

ObjectivesInfluenza vaccination is an effective method for preventing influenza virus infection. Herein, we performed a meta-analysis to quantify global influenza vaccination rates (IVRs) and the factors influencing its uptake in the general population, individuals with chronic diseases, pregnant women, and healthcare workers. MethodsRelated articles were obtained from online databases and screened according to the inclusion criteria. The pooled IVRs were calculated using the random effects model. Subgroup analyses and multivariate meta-regression were performed to determine the factors associated with influenza vaccine uptake. ResultsWe included 522 studies from 68 countries/regions. Most studies were conducted in the European region (247 studies), followed by the Western Pacific (135 studies) and American regions (100 studies). The IVRs with 95% confidence intervals (CIs) in the general population were lower (24.96%, 23.45%-26.50%) than in individuals with chronic diseases (41.65%, 40.08%-43.23%), healthcare workers (36.57%, 33.74%-39.44%), and pregnant women (25.92%, 23.18%-28.75%). The IVRs in high-income countries/regions were significantly higher than that in middle-income countries/regions. A free national or regional vaccination policy, perception of influenza vaccine efficacy and disease severity, a recommendation from healthcare workers, and having a history of influenza vaccination were positive factors for vaccine uptake (P <0.01). ConclusionOverall, global IVRs were low, especially in the general population. The studies on the IVRs, especially for priority populations, should be strengthened in Eastern Mediterranean, South-East Asian, and African regions. Free vaccination policies and the dissemination of continuous awareness campaigns are effective measures to enhance vaccination uptake.

Indirect Protection from Vaccinating Children against Influenza A Virus Infection in Households.

Influenza vaccination is an important intervention to prevent influenza virus infection. Our previous analysis suggested that indirect protection is limited in an influenza B epidemic in Hong Kong. We further analyzed six influenza A epidemics to determine such potential. We applied a statistical model to estimate household transmission dynamics in the 3 influenza A(H3N2) and 3 pandemic influenza A(H1N1) epidemics. Then, we estimated the reduction in infection risk among unvaccinated household members when all children in households are vaccinated, with different assumptions on vaccine efficacy (VE). In the optimal scenario that VE was 70%, the reduction to the total probability of infection was only marginal, with relative probabilities ranged from 0.91–0.94 when all children in households were vaccinated because community was by far the main source of infection during the six epidemics in our study. The proportion of cases attributed to household transmission was 10% (95% CrI: 7%, 13%). Individual influenza vaccination is important even when other household members are vaccinated, given the degree of indirect protection is small.

Chemically Modified Bovine β-Lactoglobulin as a Broad-Spectrum Influenza Virus Entry Inhibitor with the Potential to Combat Influenza Outbreaks.

Frequent outbreaks of the highly pathogenic influenza A virus (AIV) infection, together with the lack of broad-spectrum influenza vaccines, call for the development of broad-spectrum prophylactic agents. Previously, 3-hydroxyphthalic anhydride-modified bovine β-lactoglobulin (3HP-β-LG) was proven to be effective against human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and it has also been used in the clinical control of cervical human papillomavirus (HPV) infections. Here, we show its efficacy in potently inhibiting infection by divergent influenza A and B viruses. Mechanistic studies suggest that 3HP-β-LG binds, possibly through its negatively charged residues, to the receptor-binding domain in the hemagglutinin 1 (HA1) subunit in the HA of the influenza virus, thus inhibiting the attachment of the HA to sialic acid on host cells. The intranasal administration of 3HP-β-LG led to the protection of mice against challenges by influenza A(H1N1)/PR8, A(H3N2), and A(H7N9) viruses. Furthermore, 3HP-β-LG is highly stable when stored at 50 °C for 30 days and it shows excellent safety in vitro and in vivo. Collectively, our findings suggest that 3HP-β-LG could be successfully repurposed as an intranasal prophylactic agent to prevent influenza virus infections during influenza outbreaks.

Recommendations for Prevention and Control of Influenza in Children, 2022-2023.

This statement updates the recommendations of the American Academy of Pediatrics for the routine use of influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2022-2023 influenza season. A detailed review of the evidence supporting these recommendations is published in the accompanying technical report (http://www.pediatrics.org/cgi/doi/10.1542/peds.2022-059275). The American Academy of Pediatrics recommends annual influenza vaccination of all children without medical contraindications starting at 6 months of age. Influenza vaccination is an important strategy for protecting children and the broader community, as well as reducing the overall burden of respiratory illnesses when other viruses, including severe acute respiratory syndrome-coronavirus 2, are cocirculating. Any licensed influenza vaccine appropriate for age and health status can be administered, ideally as soon as possible in the season, without preference for one product or formulation over another. Antiviral treatment of influenza with any US Food and Drug Administration-approved, age-appropriate influenza antiviral medication is recommended for children with suspected or confirmed influenza who are hospitalized, have severe or progressive disease, or have underlying conditions that increase their risk of complications of influenza, regardless of duration of illness. Antiviral treatment should be initiated as soon as possible. Antiviral treatment may be considered in the outpatient setting for symptomatic children with suspected or confirmed influenza disease who are not at high risk for influenza complications, if treatment can be initiated within 48 hours of illness onset, and for children with suspected or confirmed influenza disease whose siblings or household contacts either are younger than 6 months or have a high-risk condition that predisposes them to complications of influenza. Antiviral chemoprophylaxis is recommended for the prevention of influenza virus infection as an adjunct to vaccination in certain individuals, especially exposed children who are at high risk for influenza complications but have not yet been immunized or who lack a sufficient immune response.