Influenza vaccine use to protect healthy children: A debated topic

Genetically Predicted Peripheral Immune Cells Mediate the Effect of Gut Microbiota on Influenza Susceptibility

The communication mechanism of the gut-lung axis has received increasing attention in recent years, particularly in acute respiratory infectious diseases such as influenza. The peripheral immune system serves as a crucial bridge between the gut and the lungs, two organs that are not in close proximity to each other. However, the specific communication mechanism involving gut microbiota, immune cells, and their anti-influenza effects in the lung remains to be further elucidated. In this study, the effects of 731 species of peripheral immune cells and 211 different gut microbiota on influenza outcomes were analyzed using a two-sample Mendelian randomization analysis. After identifying specific species of gut microbiota and peripheral immune cells associated with influenza outcomes, mediation analyses were conducted to determine the mediating effects of specific immune cells in the protective or injurious effects of influenza mediated by gut microbiota. 19 species of gut microbiota and 75 types of peripheral immune cells were identified as being associated with influenza susceptibility. After rigorous screening, 12 combinations were analyzed for mediated effects. Notably, the down-regulation of CD64 on CD14- CD16- cells mediated 21.10% and 18.55% of the protective effect of Alcaligenaceae and Dorea against influenza, respectively. In conclusion, focusing on influenza, this study genetically inferred different types of gut microbiota and peripheral immune cells to determine their protective or risk factors. Furthermore, mediation analysis was used to determine the proportion of mediating effects of peripheral immune cells in gut microbiota-mediated susceptibility to influenza. This helps elucidate the gut-lung axis mechanism by which gut microbiota affects influenza susceptibility from the perspective of regulation of peripheral immune cells.

Association of parent influenza vaccination and early childhood vaccinations using linked electronic health record data

INTRODUCTION

Parent and child vaccination behavior is related for human papillomavirus (HPV) and flu vaccine. Thus, it is likely that parental vaccination status is also associated with their children's adherence to guideline-concordant childhood vaccination schedules. We hypothesized that parent influenza (flu) vaccination would be associated with their child's vaccination status at age two.

METHODS

We used electronic health record data to identify children and linked parents seen in a community health center (CHC) within the OCHIN network (292 CHCs in 16 states). We randomly selected a child aged <2 years with ≥1 ambulatory visit between 2009-2018. Employing a retrospective, cohort study design, we used general estimating equations logistic regression to estimate the odds of a child being up-to-date on vaccinations based on their linked parents' flu vaccination status. We adjusted for relevant parent and child covariates and stratified by mother only, father only, and two-parent samples.

RESULTS

The study included 40,007 family-units: mother only = 35,444, father only = 2,784, and two parents = 1,779. A higher percentage of children were fully vaccinated if their parent or parents received a flu vaccine. Children in the two-parent sample whose parents both received a flu vaccine had more than twice the odds of being fully vaccinated, and two and a half times the odds of being fully vaccinated except flu vaccine compared to children with two parents who did not receive a flu vaccine (covariate-adjusted odds ratio [aOR] = 2.39, 95% CI = 1.67, 3.43 and aOR = 2.54, 95% CI = 1.54, 4.19, respectively).

CONCLUSIONS

Parent flu vaccination is associated with routine child vaccination. Future research is needed to understand if this relationship persists over time and in different settings.

Potent priming by inactivated whole influenza virus particle vaccines is linked to viral RNA uptake into antigen presenting cells

Current detergent or ether-disrupted split vaccines (SVs) for influenza do not always induce adequate immune responses, especially in young children. This contrasts with the whole virus particle vaccines (WPVs) originally used against influenza that were immunogenic in both adults and children but were replaced by SV in the 1970s due to concerns with reactogenicity. In this study, we re-evaluated the immunogenicity of WPV and SV, prepared from the same batch of purified influenza virus, in cynomolgus macaques and confirmed that WPV is superior to SV in priming potency. In addition, we compared the ability of WPV and SV to induce innate immune responses, including the maturation of dendritic cells (DCs) in vitro. WPV stimulated greater production of inflammatory cytokines and type-I interferon in immune cells from mice and macaques compared to SV. Since these innate responses are likely triggered by the activation of pattern recognition receptors (PRRs) by viral RNA, the quantity and quality of viral RNA in each vaccine were assessed. Although the quantity of viral RNA was similar in the two vaccines, the amount of viral RNA of a length that can be recognized by PRRs was over 100-fold greater in WPV than in SV. More importantly, 1000-fold more viral RNA was delivered to DCs by WPV than by SV when exposed to preparations containing the same amount of HA protein. Furthermore, WPV induced up-regulation of the DC maturation marker CD86 on murine DCs, while SV did not. The present results suggest that the activation of antigen-presenting DCs, by PRR-recognizable viral RNA contained in WPV is responsible for the effective priming potency of WPV observed in naïve mice and macaques. WPV is thus recommended as an alternative option for seasonal influenza vaccines, especially for children.

Why It Is Important to Develop an Effective and Safe Pediatric COVID-19 Vaccine

The need to cope with the medical, social, and economic storm due to the new coronavirus 2019 (COVID-19) pandemic as quickly as possible has led to the very rapid development of a huge number of vaccines. All these vaccines have been mainly developed in healthy adults and, in some cases, in the elderly. Children were marginally involved as, according to the clinical trial registry Clinical Trials.gov, only very few studies have included children among subjects to enroll, although just a few weeks after the pandemic declaration, the US Food and Drug Administration had highlighted the importance of vaccine evaluation in pediatrics. Availability of an effective and safe pediatric COVID-19 vaccine appears mandatory for several clinical and epidemiological reasons. However, as the development of an effective and safe pediatric vaccine seems far from easy, strong cooperation among governments, researchers, and pharmaceutical companies is highly desirable.

Global Perspectives on Immunization During Pregnancy and Priorities for Future Research and Development: An International Consensus Statement

Immunization during pregnancy has been recommended in an increasing number of countries. The aim of this strategy is to protect pregnant women and infants from severe infectious disease, morbidity and mortality and is currently limited to tetanus, inactivated influenza, and pertussis-containing vaccines. There have been recent advancements in the development of vaccines designed primarily for use in pregnant women (respiratory syncytial virus and group B Streptococcus vaccines). Although there is increasing evidence to support vaccination in pregnancy, important gaps in knowledge still exist and need to be addressed by future studies. This collaborative consensus paper provides a review of the current literature on immunization during pregnancy and highlights the gaps in knowledge and a consensus of priorities for future research initiatives, in order to optimize protection for both the mother and the infant.

How does one choose the appropriate pharmacotherapy for children with lower respiratory tract infections?

INTRODUCTION

The definition of acute lower respiratory tract infection (LRTI) includes any infection involving the respiratory tract below the level of the larynx. In children, the most common acute LRTIs, and those with the greatest clinical relevance, are community-acquired pneumonia (CAP), bronchiolitis, bronchitis and tuberculosis (TB). The clinical relevance of LRTIs implies that they must be addressed with the most effective therapy. Antibiotics and antivirals play an essential role in this regard.

AREAS COVERED

In this paper, the most recent advances in the drug treatment of LRTIs in children are discussed.

EXPERT OPINION

Although LRTIs are extremely common and one of the most important causes of hospitalization and death in children, anti-infective therapy for these diseases remains unsatisfactory. For CAP and BR, the most important problem is the overuse and misuse of antibiotics; for BCL, the lack of drugs with demonstrated efficacy, safety and tolerability; for TB, the poor knowledge on the true efficacy and safety of the new drugs specifically planned to overcome the problem of MDR M. tuberculosis strains. There is still a long way to go for the therapy of pediatric LRTIs to be considered satisfactory.

Development of Psychological Problems Among Adolescents During School Closures Because of the COVID-19 Lockdown Phase in Italy: A Cross-Sectional Survey

Background: Previous studies have shown that during COVID-19 pandemic, mainly due to the imposed lockdown, significant psychological problems had emerged in a significant part of the population, including older children and adolescents. School closure, leading to significant social isolation, was considered one of the most important reasons for pediatric mental health problems. However, how knowledge of COVID-19 related problems, modification of lifestyle and age, gender and severity of COVID-19 pandemic had influenced psychological problems of older children and adolescents has not been detailed. To evaluate these variables, a survey was carried out in Italy. Methods: This cross-sectional survey was carried out by means of an anonymous online questionnaire administered to 2,996 students of secondary and high schools living in Italian Regions with different COVID-19 epidemiology. Results: A total of 2,064 adolescent students (62.8% females; mean age, 15.4 ± 2.1 years), completed and returned the questionnaire. Most of enrolled students showed good knowledge of COVID-19-related problems. School closure was associated with significant modifications of lifestyle and the development of substantial psychological problems in all the study groups, including students living in Regions with lower COVID-19 incidence. However, in some cases, some differences, were evidenced. Sadness was significantly more frequent in females (84%) than males (68.2%; p < 0.001) and in the 14-19-year-old age group than the 11-13-year-old age group (79.2% vs. 70.2%; p < 0.001). Missing the school community was a significantly more common cause of sadness in girls (26.5% vs. 16.8%; p < 0.001), in southern Italy (26.45% vs. 20.2%; p < 0.01) and in the 14-19-year-old group (24.2% vs. 14.7%; p < 0.001). The multivariate regression analysis showed that male gender was a protective factor against negative feelings (p < 0.01), leading to a decrease of 0.63 points in the total negative feelings index. Having a family member or an acquaintance with COVID-19 increased the negative feelings index by 0.1 points (p < 0.05). Conclusions: This study shows that school closures because of the COVID-19 pandemic outbreak was associated with significant lifestyle changes in all the students, regardless of age and gender. Despite some differences in some subgroups, the study confirms that school closure can cause relevant mental health problems in older children and adolescents. This must be considered as a reason for the maintenance of all school activities, although in full compliance with the measures to contain the spread of the pandemic.

Vaccination against Paediatric Respiratory Pathogens

Acute respiratory infections (ARIs) are extremely common in children, especially those under 5 years old. They can lead to complications, super-infection, respiratory failure, and even compromised respiratory function in adulthood. For some of the responsible pathogens, vaccines are available. This review reports current issues about vaccines against the main respiratory pathogens to highlight the available strategies to reduce the burden of paediatric respiratory disease. The optimal use of influenza, pneumococcal, pertussis and measles vaccines is required in order to reduce ARI burden. Vaccination coverage rates must be improved to achieve the full benefits of these vaccines. Recently, advances in the knowledge of respiratory syncytial virus structural biology and immunology as well as the development of new techniques to generate vaccine candidates have increased the number of promising vaccines even against this harmful pathogen.