The respiratory syncytial virus vaccine landscape: lessons from the graveyard and promising candidates

Epidemiological and pathological characterization of acute respiratory infections

This research comprehensively investigates the epidemiological features and pathogen profile of acute respiratory infections (ARI) in Shihezi City, Xinjiang. A pivotal aspect of this study is the construction of a Bayes discriminant function for principal pathogen infections. This innovative methodology aims to furnish a robust scientific basis for the prevention and clinical management of ARI, potentially guiding more effective strategies in both public health and clinical settings. We compiled and examined data from January 2020 to June 2023, pertaining to patients admitted with acute respiratory infections at the First Affiliated Hospital of Shihezi University. This investigation focused on discerning patterns in epidemiology and pathogen etiology. Among 2110 cases of acute respiratory infections (ARI), 1736 underwent pathogenetic testing. Of these, 595 cases tested positive for at least one pathogen, marking a positivity rate of 34.27%. Viral detections, at a rate of 27.47%, were notably higher than bacterial detections, which stood at 6.51%. The most prevalent viruses identified were Human respiratory syncytial virus (hRSV), Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), and Human adenovirus (HAdV), while the dominant bacterial pathogens included Klebsiella pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. Co-infections were observed in 76 cases, accounting for 12.77% of positive diagnoses, predominantly involving hRSV in conjunction with other pathogens. In cases of acute bronchiolitis, hRSV was the most frequent pathogen, contributing to 23.10% of such cases. Similarly, in severe pneumonia cases, SARS-CoV-2 was predominant, accounting for 25.4% of these infections. The group with bacterial positivity exhibited elevated levels of C-reactive protein (CRP, 19.17 mg/L) and neutrophilic granulocyte percentage (NE%, 54.7%). The Bayes discriminant function demonstrated an initial validation accuracy of 74.9% and a cross-validation accuracy of 63.7%. The study underscores that hRSV, SARS-CoV-2, and HAdV are the primary pathogens in acute respiratory infections in the Shihezi region. Pathogen susceptibility exhibits variation across different age groups, with a higher pathogen detection rate in children compared to adults. The Bayes discriminant function shows significant promise in the classification and diagnosis of major pathogenic infections.

DS2 designer pre-fusion F vaccine induces strong and protective antibody response against RSV infection

DS-Cav1, SC-TM, and DS2 are distinct designer pre-fusion F proteins (pre-F) of respiratory syncytial virus (RSV) developed for vaccines. However, their immunogenicity has not been directly compared. In this study, we generated three recombinant vaccines using the chimpanzee adenovirus vector AdC68 to express DS-Cav1, SC-TM, and DS2. All three vaccines elicited robust serum binding and neutralizing antibodies following intramuscular priming and boosting. DS2 induced the strongest antibody responses, followed by SC-TM and DS-Cav1. DS2 also provided strong protection against live RSV challenge. Monoclonal antibodies (mAbs) isolated from long-lived antibody-secreting cells (ASCs) in the bone marrow six months post-immunization with AdC68-DS2 predominantly targeted site Ø as well as site II. One neutralizing antibody against site II, mAb60, conferred strong protection against live RSV infection in mice. These findings highlight the strong ability of the DS2 design in eliciting long-lived antibody responses and guide the development of next-generation RSV vaccines.

Immunogenicity and safety of Ad26.RSV.preF/RSV preF protein vaccine at predicted intermediate- and end-of-shelf-life as an evaluation of potency throughout shelf life

This study assessed three Ad26.RSV.preF/RSV preF protein combinations, combining different Ad26.RSV.preF doses and naturally aged preF protein, representing the expected critical vaccine quality attributes close to release, around intermediate shelf-life (ISL) and near-presumed end-of-shelf-life (EoSL), as a way to evaluate the vaccine immunogenicity and safety throughout its shelf-life. A single dose of Ad26.RSV.preF/RSV preF protein vaccine was administered to adults 60-75 years of age. Solicited adverse events (AEs), unsolicited AEs, and serious AEs (SAEs) were assessed for 7-day, 28-day, and 6-month periods after vaccination, respectively. RSV preF-binding antibody concentrations and RSV neutralizing titers were measured 14 days post-vaccination as primary and secondary endpoints, respectively; binding antibodies were also measured 6 months post-vaccination. The RSV preF-binding antibody responses induced by Ad26.RSV.preF/RSV preF protein vaccine lots representing the critical quality attributes around ISL and near presumed EoSL were noninferior to the responses induced by the vaccine lot representing the critical quality attributes near release. The RSV preF-binding and RSV neutralizing antibody levels measured 14 days post-vaccination were similar across the 3 groups. RSV preF-binding antibody concentrations were also similar 6 months post-vaccination. Solicited AEs were mostly mild to moderate in intensity, and a decreased reactogenicity was observed from the Release group to the ISL and EoSL group. None of the reported SAEs were considered related to study vaccination. The study provided evidence of sustained immunogenicity and safety over the intended shelf-life of the Ad26.RSV.pref/RSV preF protein vaccine. The three vaccine lots had acceptable safety profiles.

Landscape of respiratory syncytial virus

ABSTRACT

Respiratory syncytial virus (RSV) is an enveloped, negative-sense, single-stranded RNA virus of the Orthopneumovirus  genus of the Pneumoviridae family in the order Mononegavirales. RSV can cause acute upper and lower respiratory tract infections, sometimes with extrapulmonary complications. The disease burden of RSV infection is enormous, mainly affecting infants and older adults aged 75 years or above. Currently, treatment options for RSV are largely supportive. Prevention strategies remain a critical focus, with efforts centered on vaccine development and the use of prophylactic monoclonal antibodies. To date, three RSV vaccines have been approved for active immunization among individuals aged 60 years and above. For children who are not eligible for these vaccines, passive immunization is recommended. A newly approved prophylactic monoclonal antibody, Nirsevimab, which offers enhanced neutralizing activity and an extended half-life, provides exceptional protection for high-risk infants and young children. This review provides a comprehensive and detailed exploration of RSV's virology, immunology, pathogenesis, epidemiology, clinical manifestations, treatment options, and prevention strategies.

From setbacks to success: lessons from the journey of RSV vaccine development

Respiratory syncytial virus (RSV) causes high worldwide infant mortality, as well as a high disease burden in the elderly. Efforts in vaccine development over the past 60 years have recently delivered three approved vaccines and two monoclonal antibodies (mAbs). Looking back at the eventful history of RSV vaccine development, several factors can be identified that have hampered the developmental pathway, including the occurrence of enhanced RSV disease (ERD) in the first vaccine attempt and the difficulty in characterizing and stabilizing the pre-fusion F protein as a vaccine target. Moreover, the need for large trials to test vaccine efficacy, usually done late in development, and the lack of a correlate of protection (CoP) result in significant uncertainties in RSV vaccine development. The use of controlled human infection models (CHIMs) may provide a solution for some of these problems: through swift, cost-efficient and closely monitored assessment of vaccine safety and efficacy in early clinical phases, vaccines can either 'fail fast' or show results supporting further investments. Moreover, CHIMs facilitate the assessment of disease and could assist in the identification of a CoP supporting late-stage development. Although some factors may affect translatability to real-world vaccine efficacy, CHIMs can support the clinical development pathway in various ways. We advocate for, and demonstrate, a conceptual and rational design of RSV vaccine development. Assessing protective efficacy early on would result in the most cost-efficient pathway and identification of target populations should be done as early as possible. For RSV, elderly individuals and people in low- and middle-income countries are high-impact populations for RSV prevention. While RSV immunization is now available in certain regions, global access is not accomplished yet, and worldwide prevention does not seem within reach. Quick and cost-effective assessments of candidates currently in the pipeline could contribute to future successes in the battle against RSV.

A multivalent RSV vaccine based on the modified vaccinia Ankara vector shows moderate protection against disease caused by RSV in older adults in a phase 3 clinical study

Respiratory syncytial virus (RSV) causes a significant disease burden in older adults. The live recombinant vaccine based on a nonreplicating modified vaccinia Ankara (MVA-BN) poxvirus, MVA-BN-RSV, encoding for multiple proteins of RSV subtypes A and B, was assessed for efficacy against respiratory disease caused by RSV. Adults aged ≥60 years, with or without underlying chronic conditions, were enrolled and randomized in a 1:1 ratio to receive a single dose of vaccine or placebo and were followed for disease caused by RSV infection during the 2022-2023 season. The 2 primary endpoints were RSV-associated lower respiratory tract disease (LRTD) with ≥3 and ≥ 2 symptoms; acute respiratory disease (ARD) was a key secondary endpoint. The humoral RSV-specific immune response was assessed at baseline and 14 days post-vaccination. Safety was evaluated by collection of solicited adverse events (AEs) and unsolicited AEs for 7 and 28 days post-vaccination respectively, and SAEs for the entire study period. In total, 18,348 participants were included in the final efficacy and safety analyses. Vaccine efficacy was 42.9 % (95 % CI: -16.1; 71.9) against RSV-associated LRTD with ≥3 symptoms, 59.0 % (95 % CI: 34.7; 74.3) against LRTD with ≥2 symptoms, and 48.8 % (95 % CI: 25.8; 64.7) against ARD. The primary objective was not met for LRTD with ≥3 symptoms since the lower bound of the 95 % CI was below 20 %, the prespecified success criterion. The vaccine-elicited immune response showed mean fold-increases of 1.7 for RSV A and B neutralizing antibodies and 2.9 and 4.3 for RSV-specific IgG and IgA, respectively. The vaccine displayed mild to moderate reactogenicity, and no safety concerns were identified. MVA-BN-RSV induced suboptimal protection against RSV-associated LRTD, likely due to suboptimal neutralizing antibody response. The vaccine had an acceptable safety profile and confirmed immunogenicity, overall showing promise for MVA-BN-vectored constructs targeting other diseases. Trial Registration:Clinicaltrials.gov Identifier NCT05238025 (Registered February 14, 2022).

Biology of human respiratory syncytial virus: Current perspectives in immune response and mechanisms against the virus

Human respiratory syncytial virus (hRSV) remains a leading cause of morbidity and mortality in infants, young children, and older adults. hRSV infection's limited treatment and vaccine options significantly increase bronchiolitis' morbidity rates. The severity and outcome of viral infection hinge on the innate immune response. Developing vaccines and identifying therapeutic interventions suitable for young children, older adults, and pregnant women relies on comprehending the molecular mechanisms of viral PAMP recognition, genetic factors of the inflammatory response, and antiviral defense. This review covers fundamental elements of hRSV biology, diagnosis, pathogenesis, and the immune response, highlighting prospective options for vaccine development.

Immune Responses to Respiratory Syncytial Virus Vaccines: Advances and Challenges

Respiratory Syncytial Virus (RSV) is a leading cause of acute respiratory infections, particularly in children and the elderly. This virus primarily infects ciliated epithelial cells and activates alveolar macrophages and dendritic cells, triggering an innate antiviral response that releases pro-inflammatory cytokines. However, immunity generated by infection is limited, often leading to reinfection throughout life. This review focuses on the immune response elicited by newly developed and approved vaccines against RSV. A comprehensive search of clinical studies on RSV vaccine candidates conducted between 2013 and 2024 was performed. There are three primary target groups for RSV vaccines: pediatric populations, infants through maternal immunization, and the elderly. Different vaccine approaches address these groups, including subunit, live attenuated or chimeric, vector-based, and mRNA vaccines. To date, subunit RSV vaccines and the mRNA vaccine have been approved using the pre-fusion conformation of the F protein, which has been shown to induce strong immune responses. Nevertheless, several other vaccine candidates face challenges, such as modest increases in antibody production, highlighting the need for further research. Despite the success of the approved vaccines for adults older than 60 years and pregnant women, there remains a critical need for vaccines that can protect children older than six months, who are still highly vulnerable to RSV infections.

RSV Neutralizing Antibodies Following Nirsevimab and Palivizumab Dosing

BACKGROUND

Data describing respiratory syncytial virus (RSV) neutralizing antibody (nAb) levels for nirsevimab, a recently approved, extended half-life, anti-RSV fusion protein (F protein) monoclonal antibody, relative to the previous standard of care, palivizumab, have not been reported.

METHODS

MEDLEY was a randomized, palivizumab-controlled, phase 2/3 study of nirsevimab during 2 RSV seasons (season 1 and 2) in infants born preterm (≤35 weeks' gestational age; dosed season 1 only) or with congenital heart disease or chronic lung disease of prematurity (dosed seasons 1 and 2). Participants were randomly assigned to receive a single dose of nirsevimab followed by 4 monthly placebo doses, or 5 once-monthly doses of palivizumab. Anti-RSV F protein serology (ie, levels of prefusion [pre-F]/postfusion [post-F] conformation antibodies), nirsevimab and palivizumab concentrations, and RSV nAbs were measured in participant serum collected at baseline (pre-dose) and days 31, 151, and 361.

RESULTS

Serologic data were similar in seasons 1 and 2. Nirsevimab predominately conferred pre-F antibodies, whereas palivizumab conferred pre-F and post-F antibodies. Nirsevimab and palivizumab serum concentrations highly correlated with nAb levels in both seasons. In season 1, nAb levels in nirsevimab recipients were highest in day 31 samples and gradually declined but remained 17-fold above baseline at day 361. nAb levels in palivizumab recipients increased incrementally with monthly doses to day 151. nAb levels followed similar patterns in season 2. nAb levels were ∼10-fold higher with nirsevimab compared with palivizumab across both seasons.

CONCLUSIONS

Nirsevimab prophylaxis confers ∼10-fold higher and more sustained RSV nAb levels relative to palivizumab.

The circulating characteristics of common respiratory pathogens in Ningbo, China, both before and following the cessation of COVID-19 containment measures

To assess the circulating characteristics of common respiratory pathogens following the complete relaxation of non-pharmaceutical interventions (NPIs) and the cessation of the dynamic zero-COVID policy. The retrospective analysis was conducted from 14,412 patients with acute respiratory infections (ARIs) from January 24, 2020, to December 31, 2023, including Influenza A virus (IFV-A), Influenza B virus (IFV-B), Respiratory Syncytial Virus (RSV), Human Rhinovirus (HRV), Human Parainfluenza Virus (HPIV), Human Metapneumovirus (HMPV), Human Coronavirus (HCoV), Human Bocavirus (HBoV), Human Adenovirus (HAdV), and Mycoplasma pneumoniae (MP). Compared with 2020-2022, Joinpoint analysis indicated a monthly increase in overall pathogen activity in 2023, rising from an average of 43.05% to an average of 68.46%. The positive rates of IFV-A, IFV-B, HMPV, HPIV, HCoV, and MP increased, while those of HRV and RSV decreased, and no differences in HAdV and HBoV. The outbreak of IFV-A and MP was observed, the positive rate of MP has surpassed pre-COVID-19 pandemic levels and the spread of RSV was interrupted by IFV-A. Infants and toddlers were primarily infected by HRV and RSV, Children and adolescents exhibited a higher prevalence of infections with MP, IFV-A, and HRV, whereas Adults and the elderly were primarily infected by IFV-A. The incidence of co-infections rose from 4.25 to 13.73%. Restricted cubic spline models showed that the susceptible age ranges for multiple pathogens expanded. These changes serve as a reminder to stay alert in the future and offer clinicians a useful guide for diagnosing and treating.

Antibody-mediated protection against respiratory syncytial virus in children

Respiratory syncytial virus (RSV) is a major global pathogen, causing lower respiratory tract disease in at-risk populations including young children. Antibodies form a crucial layer of protection from RSV disease, particularly in immunologically naïve infants. Such antibodies are derived from the mother via transplacental transfer and breast milk, but may be particularly low in high-risk infants such as those born preterm. Maternally derived antibodies can now be supplemented by the administration of anti-RSV monoclonal antibodies, while a rising wave of maternal and paediatric vaccine strategies are approaching. The implementation of these prophylactics may profoundly decrease the healthcare burden of RSV. In this article, we review the role of antibody-mediated immunity in protecting children from RSV. We focus on maternally derived antibodies as the main source of protection against RSV and study factors that influence the scale of this transfer. The role of passive and active prophylactic approaches in protecting infants against RSV are discussed and knowledge gaps in our understanding of antibody-mediated protection against RSV are identified.

An insight into sustainable and green chemistry approaches for the synthesis of quinoline derivatives as anticancer agents

Quinolones, a key class of heterocyclics, are gaining popularity among organic and medicinal chemists due to their promising properties. Quinoline, with its broad spectrum of action, plays a primordial role in chemotherapy for cancer. Drugs include lenvatinib and its structural derivatives carbozantinib and bosutinib, and tipifarnib are the popular anticancer agents. Owing to the importance of quinoline, there are several classical methods for the synthesis such as, such as Gould-Jacobs, Conrad-Limpach, Camps cyclization, Skraup, Doebnervon Miller, Combes, Friedlander, Pfitzinger, and Niementowski synthesis. These methods are well-commended for developing an infinite variety of quinoline analogues. However, these procedures are associated with several drawbacks such as long reaction times, use of hazardous chemicals or stoichiometric proportions, difficulty of working up conditions, high temperatures, organic solvents, and the presence of numerous steps, all of which have an impact on the environment and the economy. As a result, researchers are working hard to develop green quinoline compounds in the hopes of making groundbreaking discoveries in the realm of cancer. In this review, we have highlighted significant research on quinoline-based compounds and their structure-activity relationship (SAR). Furthermore, because of the significant economic and environmental health and safety (EHS) concerns, more research is being dedicated to the green synthesis of quinolone derivatives. The current review offers recent advances in quinoline derivatives as anticancer agents for green synthesis using microwave, ultrasound, and one-pot synthesis. We believe that our findings will provide useful insight and inspire more green research on this framework to produce powerful and selective quinoline derivatives.

Global progress in clinical research on human respiratory syncytial virus vaccines

Human respiratory syncytial virus (hRSV) not only affects newborns but also older adults, contributing to a substantial worldwide burden of disease. However, only three approved hRSV vaccines remain commercially available to date. The development of a safe, practical and broad-spectrum vaccine suitable for all age groups remains extremely challenging. Using five different approaches-live-attenuated, recombinant-vector, subunit, particle-based, and mRNA-nearly 30 hRSV vaccine candidates are currently conducting clinical trials worldwide; moreover, > 30 vaccines are under preclinical evaluation. This review presents a comprehensive overview of these hRSV vaccines along with prospects for the development of infectious disease vaccines in the post-COVID-19 pandemic era.

Whole genome molecular analysis of respiratory syncytial virus pre and during the COVID-19 pandemic in Free State province, South Africa

Respiratory syncytial virus (RSV) is the most predominant viral pathogen worldwide in children with lower respiratory tract infections. The Coronavirus disease 2019 (COVID-19) pandemic and resulting nonpharmaceutical interventions perturbed the transmission pattern of respiratory pathogens in South Africa. A seasonality shift and RSV resurgence was observed in 2020 and 2021, with several infected children observed. Conventional RSV-positive nasopharyngeal swabs were collected from various hospitals in the Free State province, Bloemfontein, South Africa, from children suffering from respiratory distress and severe acute respiratory infection between 2020 to 2021. Overlapping genome fragments were amplified and complete genomes were sequenced using the Illumina MiSeq platform. Maximum likelihood phylogenetic and evolutionary analysis were performed on both RSV-A/-B G-genes with published reference sequences from GISAID and GenBank. Our study strains belonged to the RSV-A GA2.3.2 and RSV-B GB5.0.5a clades. The upsurge of RSV was due to pre-existing strains that predominated in South Africa and circulating globally also driving these off-season RSV outbreaks during the COVID-19 pandemic. The variants responsible for the resurgence were phylogenetically related to pre-pandemic strains and could have contributed to the immune debt resulting from pandemic imposed restrictions. The deviation of the RSV season from the usual pattern affected by the COVID-19 pandemic highlights the need for ongoing genomic surveillance and the identification of genetic variants to prevent unforeseen outbreaks in the future.

Generation of novel respiratory syncytial virus vaccine candidate antigens that can induce high levels of prefusion-specific antibodies

Respiratory syncytial virus (RSV) infection is an acute respiratory infection caused by RSV. It occurs worldwide, and for over 50 years, several attempts have been made to research and develop vaccines to prevent RSV infection; effective preventive vaccines are eagerly awaited. The RSV fusion (F) protein, which has gained attention as a vaccine antigen, causes a dynamic structural change from the preF to postF state. Therefore, the structural changes in proteins must be regulated to produce a vaccine antigen that can efficiently induce antibodies with high virus-neutralizing activity. We successfully discovered several mutations that stabilized the antigen site Ø in the preF state, trimerized it, and improved the level of protein expression through observation and computational analysis of the RSV-F protein structure and amino acid mutation analysis of RSV strains. The four RSV-F protein mutants that resulted from the combination of these effective mutations stably conserved a wide range of preF- and trimeric preF-specific epitopes with high virus-neutralizing activity. Absorption assay using human serum revealed that mutants constructed bound to antibodies with virus-neutralizing activity that were induced by natural RSV infection, whereas they hardly bound to anti-postF antibodies without virus-neutralizing activity. Furthermore, mouse immunization demonstrated that our constructed mutants induced a high percentage of antibodies that bind to the preF-specific antigen site. These characteristics suggest that the mutants constructed can be superior vaccine antigens from the viewpoint of RSV infection prevention effect and safety.

Clinical Impact of Serious Respiratory Disease in Children Under the Age of 2 Years During the 2021-2022 Bronchiolitis Season in England, Scotland, and Ireland

BACKGROUND

Interventions introduced to reduce the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to a widespread reduction in childhood infections. However, from spring 2021 onwards the United Kingdom and Ireland experienced an unusual out-of-season epidemic of respiratory disease.

METHODS

We conducted a prospective observational study (BronchStart), enrolling children 0-23 months of age presenting with bronchiolitis, lower respiratory tract infection, or first episode of wheeze to 59 emergency departments across England, Scotland, and Ireland from May 2021 to April 2022. We combined testing data with national admissions datasets to infer the impact of respiratory syncytial virus (RSV) disease.

RESULTS

The BronchStart study collected data on 17 899 presentations for 17 164 children. Risk factors for admission and escalation of care included prematurity and congenital heart disease, but most admissions were for previously healthy term-born children. Of those aged 0-11 months who were admitted and tested for RSV, 1907 of 3912 (48.7%) tested positive. We estimate that every year in England and Scotland 28 561 (95% confidence interval, 27 637-29 486) infants are admitted with RSV infection.

CONCLUSIONS

RSV infection was the main cause of hospitalizations in this cohort, but 51.3% of admissions in infants were not associated with the virus. The majority of admissions were in previously healthy term-born infants.

Mechanisms of antibody mediated immunity - Distinct in early life

Immune responses in early life are characterized by a failure to robustly generate long-lasting protective responses against many common pathogens or upon vaccination. This is associated with a reduced ability to generate T-cell dependent high affinity antibodies. This review highlights the differences in T-cell dependent antibody responses observed between infants and adults, in particular focussing on the alterations in immune cell function that lead to reduced T follicular helper cell-B cell crosstalk within germinal centres in early life. Understanding the distinct functional characteristics of early life humoral immunity, and how these are regulated, will be critical in guiding age-appropriate immunological interventions in the very young.

Association of respiratory infections and the impact of vaccinations on cardiovascular diseases

Influenza, pneumococcal, severe acute respiratory syndrome coronavirus 2, and respiratory syncytial virus infections are important causes of high morbidity and mortality in the elderly. Beyond the burden of infectious diseases, they are also associated with several non-infectious complications like cardiovascular events. A growing body of evidence in prospective studies and meta-analyses has shown the impact of influenza and pneumococcal vaccines on types of cardiovascular outcomes in the general population. Influenza vaccination showed a potential benefit for primary and secondary prevention of cardiovascular diseases across all ages. A reduced risk of cardiovascular events for individuals aged 65 years and older was associated with pneumococcal vaccination. Despite scientific evidence on the effectiveness, safety, and benefits of the vaccines and recommendations to vaccinate elderly patients and those with risk factors, vaccination rates remain sub-optimal in this population. Doubts about vaccine necessity or efficacy and concerns about possible adverse events in patients and physicians refer to delayed acceptance. Vaccination campaigns targeting increasing professional recommendations and public perceptions should be implemented in the coming years. The aim of this review paper is to summarize the effect of vaccination in the field of cardiovascular disease to achieve a higher vaccination rate in this patient population.

Adjuvant-dependent impact of inactivated SARS-CoV-2 vaccines during heterologous infection by a SARS-related coronavirus

Whole virus-based inactivated SARS-CoV-2 vaccines adjuvanted with aluminum hydroxide have been critical to the COVID-19 pandemic response. Although these vaccines are protective against homologous coronavirus infection, the emergence of novel variants and the presence of large zoonotic reservoirs harboring novel heterologous coronaviruses provide significant opportunities for vaccine breakthrough, which raises the risk of adverse outcomes like vaccine-associated enhanced respiratory disease. Here, we use a female mouse model of coronavirus disease to evaluate inactivated vaccine performance against either homologous challenge with SARS-CoV-2 or heterologous challenge with a bat-derived coronavirus that represents a potential emerging disease threat. We show that inactivated SARS-CoV-2 vaccines adjuvanted with aluminum hydroxide can cause enhanced respiratory disease during heterologous infection, while use of an alternative adjuvant does not drive disease and promotes heterologous viral clearance. In this work, we highlight the impact of adjuvant selection on inactivated vaccine safety and efficacy against heterologous coronavirus infection.

Respiratory syncytial virus vaccination during pregnancy for improving infant outcomes

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections (LRTIs) in infants. Maternal RSV vaccination is a preventive strategy of great interest, as it could have a substantial impact on infant RSV disease burden. In recent years, the clinical development of maternal RSV vaccines has advanced rapidly.

OBJECTIVES

To assess the efficacy and safety of maternal respiratory syncytial virus (RSV) vaccination for preventing RSV disease in infants.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register and two other trials registries on 21 October 2022. We updated the search on 27 July 2023, when we searched MEDLINE, Embase, CENTRAL, CINAHL, and two trials registries. Additionally, we searched the reference lists of retrieved studies and conference proceedings. There were no language restrictions on our searches.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing maternal RSV vaccination with placebo or no intervention in pregnant women of any age. The primary outcomes were hospitalisation with clinically confirmed or laboratory-confirmed RSV disease in infants. The secondary outcomes covered adverse pregnancy outcomes (intrauterine growth restriction, stillbirth, and maternal death) and adverse infant outcomes (preterm birth, congenital abnormalities, and infant death).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods and assessed the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included six RCTs (25 study reports) involving 17,991 pregnant women. The intervention was an RSV pre-F protein vaccine in four studies, and an RSV F protein nanoparticle vaccine in two studies. In all studies, the comparator was a placebo (saline, formulation buffer, or sterile water). We judged four studies at overall low risk of bias and two studies at overall high risk (mainly due to selection bias). All studies were funded by pharmaceutical companies. Maternal RSV vaccination compared with placebo reduces infant hospitalisation with laboratory-confirmed RSV disease (risk ratio (RR) 0.50, 95% confidence interval (CI) 0.31 to 0.82; 4 RCTs, 12,216 infants; high-certainty evidence). Based on an absolute risk with placebo of 22 hospitalisations per 1000 infants, our results represent 11 fewer hospitalisations per 1000 infants from vaccinated pregnant women (15 fewer to 4 fewer). No studies reported infant hospitalisation with clinically confirmed RSV disease. Maternal RSV vaccination compared with placebo has little or no effect on the risk of congenital abnormalities (RR 0.96, 95% CI 0.88 to 1.04; 140 per 1000 with placebo, 5 fewer per 1000 with RSV vaccination (17 fewer to 6 more); 4 RCTs, 12,304 infants; high-certainty evidence). Maternal RSV vaccination likely has little or no effect on the risk of intrauterine growth restriction (RR 1.32, 95% CI 0.75 to 2.33; 3 per 1000 with placebo, 1 more per 1000 with RSV vaccination (1 fewer to 4 more); 4 RCTs, 12,545 pregnant women; moderate-certainty evidence). Maternal RSV vaccination may have little or no effect on the risk of stillbirth (RR 0.81, 95% CI 0.38 to 1.72; 3 per 1000 with placebo, no difference with RSV vaccination (2 fewer to 3 more); 5 RCTs, 12,652 pregnant women). There may be a safety signal warranting further investigation related to preterm birth. This outcome may be more likely with maternal RSV vaccination, although the 95% CI includes no effect, and the evidence is very uncertain (RR 1.16, 95% CI 0.99 to 1.36; 6 RCTs, 17,560 infants; very low-certainty evidence). Based on an absolute risk of 51 preterm births per 1000 infants from pregnant women who received placebo, there may be 8 more per 1000 infants from pregnant women with RSV vaccination (1 fewer to 18 more). There was one maternal death in the RSV vaccination group and none in the placebo group. Our meta-analysis suggests that RSV vaccination compared with placebo may have little or no effect on the risk of maternal death (RR 3.00, 95% CI 0.12 to 73.50; 3 RCTs, 7977 pregnant women; low-certainty evidence). The effect of maternal RSV vaccination on the risk of infant death is very uncertain (RR 0.81, 95% CI 0.36 to 1.81; 6 RCTs, 17,589 infants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

The findings of this review suggest that maternal RSV vaccination reduces laboratory-confirmed RSV hospitalisations in infants. There are no safety concerns about intrauterine growth restriction and congenital abnormalities. We must be careful in drawing conclusions about other safety outcomes owing to the low and very low certainty of the evidence. The evidence available to date suggests RSV vaccination may have little or no effect on stillbirth, maternal death, and infant death (although the evidence for infant death is very uncertain). However, there may be a safety signal warranting further investigation related to preterm birth. This is driven by data from one trial, which is not fully published yet. The evidence base would be much improved by more RCTs with substantial sample sizes and well-designed observational studies with long-term follow-up for assessment of safety outcomes. Future studies should aim to use standard outcome measures, collect data on concomitant vaccines, and stratify data by timing of vaccination, gestational age at birth, race, and geographical setting.

Melatonin suppresses TLR4-mediated RSV infection in the central nervous cells by inhibiting NLRP3 inflammasome formation and autophagy

Respiratory syncytial virus (RSV) infects neuronal cells in the central nervous system (CNS), resulting in neurological symptoms. In the present study, we intended to explore the mechanism of RSV infection-induced neuroinflammatory injury from the perspective of the immune response and sought to identify effective protective measures against the injury. The findings showed that toll-like receptor 4 (TLR4) was activated after RSV infection in human neuronal SY5Y cells. Furthermore, TLR4 activation induced autophagy and apoptosis in neuronal cells, promoted the formation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, and increased the secretion of downstream inflammatory cytokines such as interleukin-1β (IL-1β), interleukin-18 (IL-18) and tumour necrosis factor-α (TNF-α). Interestingly, blockade of TLR4 or treatment with exogenous melatonin significantly suppressed TLR4 activation as well as TLR4-mediated apoptosis, autophagy and immune responses. Therefore, we infer that melatonin may act on the TLR4 to ameliorate RSV-induced neuronal injury, which provides a new therapeutic target for RSV infection.

A potential bivalent mRNA vaccine candidate protects against both RSV and SARS-CoV-2 infections

As the world continues to confront severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respiratory syncytial virus (RSV) is also causing severe respiratory illness in millions of infants, elderly individuals, and immunocompromised people globally. Exacerbating the situation is the fact that co-infection with multiple viruses is occurring, something which has greatly increased the clinical severity of the infections. Thus, our team developed a bivalent vaccine that delivered mRNAs encoding SARS-CoV-2 Omicron spike (S) and RSV fusion (F) proteins simultaneously, SF-LNP, which induced S and F protein-specific binding antibodies and cellular immune responses in BALB/c mice. Moreover, SF-LNP immunization effectively protected BALB/c mice from RSV infection and hamsters from SARS-CoV-2 Omicron infection. Notably, our study pointed out the antigenic competition problem of bivalent vaccines and provided a solution. Overall, our results demonstrated the potential of preventing two infectious diseases with a single vaccine and provided a paradigm for the subsequent design of multivalent vaccines.

Maternal awareness, acceptability and willingness towards respiratory syncytial virus (RSV) vaccination during pregnancy in Ireland

BACKGROUND

Respiratory syncytial virus (RSV) is the world's leading cause of viral acute lower respiratory infections (ALRI) in infants. WHO has identified maternal RSV vaccination a priority and candidate vaccines are in development; however, vaccine hesitancy remains an impediment to successful implementation of maternal immunization. This study, the largest antenatal survey conducted to-date, aimed to examine maternal RSV awareness, likely acceptance of RSV vaccination in pregnancy, and attitudes to maternal vaccination.

METHODS

Pregnant women of all gestations attending antenatal clinic of a university maternity hospital in Ireland were invited to participate. An information leaflet provided, consent obtained, and survey administered examining RSV awareness, willingness to avail of antenatal RSV vaccination, factors influencing acceptability and preferred sources of assistance. Research Ethics Committee (REC) approval obtained, and general data protection regulation (GDPR) guidelines followed.

RESULTS

528 women completed the survey. A large proportion (75.6%) had never heard of RSV, yet 48.5% would still avail of a vaccine, 45.8% were undecided and only 5.3% would not. The main factor making vaccination acceptable to women (76.4%) was that it protects their infant from illness (p < .001, CV 0.336 for association with acceptance) and general practitioner (GP) was the preferred guidance source in decision-making (57.7%).

CONCLUSIONS

Despite low levels of maternal awareness of RSV, pregnant women in Ireland are open to availing of antenatal vaccination. Maternal immunization strategies need to focus on infant's protection from RSV-associated ALRI along with vaccine safety, and build on an interdisciplinary collaboration of maternal, neonatal, primary care and public health services.

Cryo-electron microscopy-based drug design

Structure-based drug design (SBDD) has gained popularity owing to its ability to develop more potent drugs compared to conventional drug-discovery methods. The success of SBDD relies heavily on obtaining the three-dimensional structures of drug targets. X-ray crystallography is the primary method used for solving structures and aiding the SBDD workflow; however, it is not suitable for all targets. With the resolution revolution, enabling routine high-resolution reconstruction of structures, cryogenic electron microscopy (cryo-EM) has emerged as a promising alternative and has attracted increasing attention in SBDD. Cryo-EM offers various advantages over X-ray crystallography and can potentially replace X-ray crystallography in SBDD. To fully utilize cryo-EM in drug discovery, understanding the strengths and weaknesses of this technique and noting the key advancements in the field are crucial. This review provides an overview of the general workflow of cryo-EM in SBDD and highlights technical innovations that enable its application in drug design. Furthermore, the most recent achievements in the cryo-EM methodology for drug discovery are discussed, demonstrating the potential of this technique for advancing drug development. By understanding the capabilities and advancements of cryo-EM, researchers can leverage the benefits of designing more effective drugs. This review concludes with a discussion of the future perspectives of cryo-EM-based SBDD, emphasizing the role of this technique in driving innovations in drug discovery and development. The integration of cryo-EM into the drug design process holds great promise for accelerating the discovery of new and improved therapeutic agents to combat various diseases.

Effectiveness of Vaccines and Monoclonal Antibodies Against Respiratory Syncytial Virus: Generic Protocol for Register-Based Cohort Study

Several immunization products are currently being developed against respiratory syncytial virus (RSV) for children, pregnant females, and older adults, and some products have already received authorization. Therefore, studies to monitor the effectiveness of these products are needed in the following years. To assist researchers to conduct postmarketing studies, we developed a generic protocol for register-based cohort studies to evaluate immunization product effectiveness against RSV-specific and nonspecific outcomes. To conduct a study on the basis of this generic protocol, the researchers can use any relevant databases or healthcare registers that are available at the study site.

Immunogenicity of a recombinant plant-produced respiratory syncytial virus F subunit vaccine in mice

Respiratory syncytial virus (RSV) is a highly infectious respiratory virus that causes serious illness, particularly in young children, elderly people, and those with immunocompromised individuals. RSV infection is the leading cause of infant hospitalization and can lead to serious complications such as pneumonia and bronchiolitis. Currently, there is an RSV vaccine approved exclusively for the elderly population, but no approved vaccine specifically designed for infants or any other age groups. Therefore, it is crucial to continue the development of an RSV vaccine specifically tailored for these populations. In this study, the immunogenicity of the two plant-produced RSV-F Fc fusion proteins (Native construct and structural stabilized construct) were examined to assess them as potential vaccine candidates for RSV. The RSV-F Fc fusion proteins were transiently expressed in Nicotiana benthamiana and purified using protein A affinity column chromatography. The recombinant RSV-F Fc fusion protein was recognized by the monoclonal antibody Motavizumab specific against RSV-F protein. Moreover, the immunogenicity of the two purified RSV-F Fc proteins were evaluated in mice by formulating with different adjuvants. According to our results, the plant-produced RSV-F Fc fusion protein is immunogenic in mice. These preliminary findings, demonstrate the immunogenicity of plant-based RSV-F Fc fusion protein, however, further preclinical studies such as antigen dose and adjuvant optimization, safety, toxicity, and challenge studies in animal models are necessary in order to prove the vaccine efficacy.

Validity of Clinical Severity Scores for Respiratory Syncytial Virus: A Systematic Review

BACKGROUND

Respiratory syncytial virus (RSV) is a widespread respiratory pathogen, and RSV-related acute lower respiratory tract infections are the most common cause of respiratory hospitalization in children <2 years of age. Over the last 2 decades, a number of severity scores have been proposed to quantify disease severity for RSV in children, yet there remains no overall consensus on the most clinically useful score.

METHODS

We conducted a systematic review of English-language publications in peer-reviewed journals published since January 2000 assessing the validity of severity scores for children (≤24 months of age) with RSV and/or bronchiolitis, and identified the most promising scores. For included articles, (1) validity data were extracted, (2) quality of reporting was assessed using the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis checklist (TRIPOD), and (3) quality was assessed using the Prediction Model Risk Of Bias Assessment Tool (PROBAST). To guide the assessment of the validity data, standardized cutoffs were employed, and an explicit definition of what we required to determine a score was sufficiently validated.

RESULTS

Our searches identified 8541 results, of which 1779 were excluded as duplicates. After title and abstract screening, 6670 references were excluded. Following full-text screening and snowballing, 32 articles, including 31 scores, were included. The most frequently assessed scores were the modified Tal score and the Wang Bronchiolitis Severity Score; none of the scores were found to be sufficiently validated according to our definition. The reporting and/or design of all the included studies was poor. The best validated score was the Bronchiolitis Score of Sant Joan de Déu, and a number of other promising scores were identified.

CONCLUSIONS

No scores were found to be sufficiently validated. Further work is warranted to validate the existing scores, ideally in much larger datasets.

Bacteria and viruses and their role in the preschool wheeze to asthma transition

Wheezing is the cardinal symptom of asthma; its presence early in life, mostly caused by viral infections, is a major risk factor for the establishment of persistent or recurrent disease. Early-life wheezing and asthma exacerbations are triggered by common respiratory viruses, mainly rhinoviruses (RV), and to a lesser extent, respiratory syncytial virus, parainfluenza, human metapneumovirus, coronaviruses, adenoviruses, influenza, and bocavirus. The excess presence of bacteria, several of which are part of the microbiome, has also been identified in association with wheezing and acute asthma exacerbations, including haemophilus influenza, streptococcus pneumoniae, moraxella catarrhalis, mycoplasma pneumoniae, and chlamydophila pneumonia. While it is not clear when asthma starts, its characteristics develop over time. Airway remodeling already appears between the ages of 1 and 3 years of age even prior to the presence of atopic inflammation or an asthma diagnosis. The role of genetic defect or variations hampering the airway epithelium in response to environmental stimuli and severe disease morbidity are now considered as major determinants for early structural changes. Repeated viral infections can induce and perpetuate airway hyperresponsiveness. Allergic sensitization, that often precedes infection-induced wheezing, shifts inflammation toward type-2, while common respiratory infections themselves promote type-2 inflammation. Nevertheless, most children who wheeze with viral infections during infancy and during preschool years do not develop persistent asthma. Multiple factors, including illness severity, viral etiology, allergic sensitization, and the exposome, are associated with disease persistence. Here, we summarize current knowledge and developments in infection epidemiology of asthma in children, describing the known impact of each individual agent and mechanisms of transition from recurrent wheeze to asthma.

Psychometric evaluation of the respiratory syncytial virus infection, intensity and impact questionnaire (RSV-iiiQ) in adults

BACKGROUND

Despite a number of respiratory syncytial virus (RSV) vaccine candidates being tested in clinical trials, disease-specific, self-reported instruments assessing symptom severity of RSV infection from the perspective of adult patients are still needed. The RSV Infection, Intensity and Impact Questionnaire (RSV-iiiQ) was adapted from the Influenza Intensity and Impact Questionnaire (FluiiQ™). This study evaluated some measurement properties of the RSV-iiiQ.

METHODS

Data were collected in a web-based survey over two consecutive days. Participants completed the RSV-iiiQ, the Patient Global Impression of Severity, Sheehan Disability Scale, Patient Global Impression of Change, EQ-5D-5L, and a demographic questionnaire. Test-retest reliability, internal consistency, construct validity, and responsiveness of the RSV-iiiQ scales were assessed.

RESULTS

111 adults with RSV were enrolled and self-reported a variety of symptoms across the range of disease severity via a web-based platform. The RSV-iiiQ scales demonstrated satisfactory test-retest reliability, construct validity, and discriminating ability. One-factor confirmatory factor analyses confirmed that each of the four scales was sufficiently unidimensional, and internal consistencies indicated that the computation of RSV-iiiQ scale scores was plausible. Correlation-based analyses provided support for the construct validity of the RSV-iiiQ scores, and known groups analyses supported discriminating ability. Estimates of responsiveness of the scale scores were also satisfactory.

CONCLUSIONS

RSV infection is highly symptomatic and causes significant disease burden, and self-report instruments assessing symptom severity and impact are important for evaluation of new treatments. This study describes the preliminary psychometric properties of the RSV-iiiQ and indicates this tool may be useful for the assessment of the severity of symptoms and impact of acute RSV infection in adults. The findings also indicated two items, Runny nose and Ear pain, may be unnecessary and should be revisited using item response theory analysis with a larger sample size.

Enabling methanol fixation of pediatric nasal wash during respiratory illness for single cell sequencing in comparison with fresh samples

BACKGROUND

Lower respiratory tract infection (LRTI) including pneumonia, bronchitis, and bronchiolitis is the sixth leading cause of mortality around the world and leading cause of death in children under 5 years. Systemic immune response to viral infection is well characterized. However, there is little data regarding the immune response at the upper respiratory tract mucosa. The upper respiratory mucosa is the site of viral entry, initial replication and the first barrier against respiratory infections. Lower respiratory tract samples can be challenging to obtain and require more invasive procedures. However, nasal wash (NW) samples from the upper respiratory tract can be obtained with minimal discomfort to the patient.

METHOD

In a pilot study, we developed a protocol using NW samples obtained from hospitalized children with LRTI that enables single cell RNA sequencing (scRNA-seq) after the NW sample is methanol-fixed.

RESULTS

We found no significant changes in scRNA-seq qualitative and quantitative parameters between methanol-fixed and fresh NW samples.

CONCLUSIONS

We present a novel protocol to enable scRNA-seq in NW samples from children admitted with LRTI. With the inherent challenges associated with clinical samples, the protocol described allows for processing flexibility as well as multicenter collaboration.

IMPACT

There are no significant differences in scRNA-seq qualitative and quantitative parameters between methanol fixed and fresh Pediatric Nasal wash samples. The study demonstrates the effectiveness of methanol fixation process on preserving respiratory samples for single cell sequencing. This enables Pediatric Nasal wash specimen for single cell RNA sequencing in pediatric patients with respiratory tract infection and allows processing flexibility and multicenter collaboration.

Efficacy and safety of respiratory syncytial virus vaccination during pregnancy to prevent lower respiratory tract illness in newborns and infants: a systematic review and meta-analysis of randomized controlled trials

To evaluate the effectiveness and safety of respiratory syncytial virus (RSV) vaccination during pregnancy in preventing lower respiratory tract infection (LRTI) in infants and neonates, we conducted a systematic search of randomized controlled trials (RCTs) in five databases (PubMed, Embase and Cochrane Library, Web of Science, Cochrane Center Register of Controlled trial) until 1 May 2023. We performed a meta-analysis of the eligible trials using RevMan5.4.1 software. Our analysis included six articles and five RCTs. The meta-analysis revealed significant differences in the incidences of LRTI [risk ratio (RR): 0.64; 95% confidence interval (CI): 0.43, 0.96; p = 0.03)] and severe LRTI (RR: 0.37; 95% CI: 0.18, 0.79; p = 0.01) between the vaccine group and the placebo group for newborns and infants. These differences were observed at 90, 120, and 150 days after birth (p = 0.003, p = 0.05, p = 0.02, p = 0.03, p = 0.009, p = 0.05). At 180 days after birth, there was a significant difference observed in the incidence of LRTI between the two groups (RR: 0.43; 95% CI: 0.21, 0.90; p = 0.02). The safety results showed a significant difference in the incidence of common adverse events between the two groups (RR: 1.08; 95% CI: 1.04, 1.12; p < 0.0001). However, there was no significant difference observed in the incidence of serious adverse events (RR: 1.05; 95% CI: 0.97, 1.15; p = 0.23), common and serious adverse events (RR: 1.02; 95% CI: 0.96, 1.10; p = 0.23), or common and serious adverse events among pregnant women and newborns and infants (RR: 0.98; 95% CI: 0.93, 1.04; p = 0.52). In conclusion, maternal RSV vaccination is an effective and safe immunization strategy for preventing LRTI in postpartum infants, with greater efficacy observed within the first 150 days after birth.

RNA therapeutics for infectious diseases

Ribonucleic acids (RNAs), including the messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA), play important roles in living organisms and viruses. In recent years, the RNA-based technologies including the RNAs inhibiting other RNA activities, the RNAs targeting proteins, the RNAs reprograming genetic information, and the RNAs encoding therapeutical proteins, are useful methods to apply in prophylactic and therapeutic vaccines. In this review, we summarize and highlight the current application of the RNA therapeutics, especially on mRNA vaccines which have potential for prevention and treatment against human and animal infectious diseases.

Evaluation of antibody-based preventive alternatives for respiratory syncytial virus: a novel multi-criteria decision analysis framework and assessment of nirsevimab in Spain

BACKGROUND

Respiratory syncytial virus (RSV) is a highly infectious disease that poses a significant clinical and medical burden, as well as social disruption and economic costs, recognized by the World Health Organization as a public health issue. After several failed attempts to find preventive candidates (compounds, products, including vaccines), new alternatives might be available, one being nirsevimab, the first and only option approved for RSV prevention in neonates and infants during their first RSV season. The objective of this study was to develop a novel multi-criteria decision analysis (MCDA) framework for RSV antibody-based preventive alternatives and to use it to assess the value of nirsevimab vs. placebo as a systematic immunization approach to prevent RSV in neonates and infants during their first RSV season in Spain.

METHODS

Based on a pre-established model called Vaccinex, an ad-hoc MCDA framework was created to reflect relevant attributes for the assessment of current and future antibody-based preventive measures for RSV. The estimated value of nirsevimab was obtained by means of an additive linear model combining weights and scores assigned by a multidisciplinary committee of 9 experts. A retest and three sensitivity analyses were conducted.

RESULTS

Nirsevimab was evaluated through a novel framework with 26 criteria by the committee as a measure that adds value (positive final estimated value: 0.56 ± 0.11) to the current RSV scenario in Spain, by providing a high efficacy for prevention of neonates and infants. In addition, its implementation might generate cost savings in hospitalizations and to the healthcare system and increase the level of public health awareness among the general population, while reducing health inequities.

CONCLUSIONS

Under a methodology with increasing use in the health field, nirsevimab has been evaluated as a measure which adds value for RSV prevention in neonates and infants during their first RSV season in Spain.

Safety and Immunogenicity of a ChAd155-Vectored Respiratory Syncytial Virus Vaccine in Infants 6-7 Months of age: A Phase 1/2 Randomized Trial

BACKGROUND

Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections in infants. This phase 1/2, observer-blind, randomized, controlled study assessed the safety and immunogenicity of an investigational chimpanzee-derived adenoviral vector RSV vaccine (ChAd155-RSV, expressing RSV F, N, and M2-1) in infants.

METHODS

Healthy 6- to 7-month-olds were 1:1:1-randomized to receive 1 low ChAd155-RSV dose (1.5 × 1010 viral particles) followed by placebo (RSV_1D); 2 high ChAd155-RSV doses (5 × 1010 viral particles) (RSV_2D); or active comparator vaccines/placebo (comparator) on days 1 and 31. Follow-up lasted approximately 2 years.

RESULTS

Two hundred one infants were vaccinated (RSV_1D: 65; RSV_2D: 71; comparator: 65); 159 were RSV-seronaive at baseline. Most solicited and unsolicited adverse events after ChAd155-RSV occurred at similar or lower rates than after active comparators. In infants who developed RSV infection, there was no evidence of vaccine-associated enhanced respiratory disease (VAERD). RSV-A neutralizing titers and RSV F-binding antibody concentrations were higher post-ChAd155-RSV than postcomparator at days 31, 61, and end of RSV season 1 (mean follow-up, 7 months). High-dose ChAd155-RSV induced stronger responses than low-dose, with further increases post-dose 2.

CONCLUSIONS

ChAd155-RSV administered to 6- to 7-month-olds had a reactogenicity/safety profile like other childhood vaccines, showed no evidence of VAERD, and induced a humoral immune response. Clinical Trials Registration. NCT03636906.

The global burden of lower respiratory infections attributable to respiratory syncytial virus in 204 countries and territories, 1990-2019: findings from the Global Burden of Disease Study 2019

AIMS

The purpose of this study is to investigate the global epidemiological characteristics of lower respiratory infections (LRI) burden attributable to respiratory syncytial virus (RSV) from 1990 to 2019.

MATERIALS AND METHODS

We used the recent Global Burden of Disease Study (GBD) 2019 to systematically evaluate the current burden and temporal trend of LRI burden attributable to RSV by global, age, sex, geographic location, and socio-economic status.

RESULTS

Globally, the disability-adjusted life years (DALYs) cases of LRI attributable to RSV dropped from an estimated 39,964,488 [95% uncertainty interval (UI): 16,825, 572 to 68,800,553] in 1990 to 14,956,514 (95%UI: 6,271,751 to 25,910,753) in 2019 and estimated death cases droped from 541,172 (95%UI:226,614 to 958,596) to 338,495 (95%UI:126,555 to 667,109) from1990 to 2019. Similarly, age-standardized DALYs rate of LRI attributable to RSV decreased from an estimated 646.2 (95%UI: 276.9 to 1121.5) in 1990 to 218.3 (95%UI:92.1 to 376.8) in 2019 and estimated age-standardized deaths rate decreased from 10.3 (95%UI:4.1 to 18.5) to 4.8 (95%UI:1.8 to 9.3) between 1990 and 2019. In 2019, the highest age-standardized DALYs and death rates of LRI attributable to RSV were seen in the lower SDI regions, children and old people. From 1990 to 2019, age-standardized DALYs and death rates of LRI attributable to RSV decreased with increasing SDI.

CONCLUSIONS

In this study, we found that the LRI burden attributable to RSV decreased significantly from 1990 to 2019. However, the lower SDI regions, children and old people urgently require cost-effective interventions to prevent and reduce the LRI burden attributable to RSV.

RSV vaccination in older adults: Addressing vaccine hesitancy using the 3C model

The first vaccine against respiratory syncytial virus (RSV) targeting older adults was approved for use in Canada in August 2023. As a frequent first point of contact for Canadians seeking advice on vaccination and the most common setting for the administration of influenza vaccines, community pharmacies will also play a role in RSV vaccination efforts. To address vaccine hesitancy confidently and effectively, pharmacists must be equipped with knowledge of the factors that affect a person's decision on whether to be vaccinated or not. The 3C Model of Vaccine Hesitancy summarizes these as complacency, confidence and convenience. This article introduces the model and describes the often-underrecognized relevance of RSV to older adults, including risk factors and burden of disease. It also reviews the history and status of vaccine development and approval and presents clinical trial data to equip pharmacists to discuss RSV vaccination with older adults who express vaccine hesitancy.

Controlled Human Infection Challenge Studies with RSV

Despite considerable momentum in the development of RSV vaccines and therapeutics, there remain substantial barriers to the development and licensing of effective agents, particularly in high-risk populations. The unique immunobiology of RSV and lack of clear protective immunological correlates has held back RSV vaccine development, which, therefore, depends on large and costly clinical trials to demonstrate efficacy. Studies involving the deliberate infection of human volunteers offer an intermediate step between pre-clinical and large-scale studies of natural infection. Human challenge has been used to demonstrate the potential efficacy of vaccines and antivirals while improving our understanding of the protective immunity against RSV infection. Early RSV human infection challenge studies determined the role of routes of administration and size of inoculum on the disease. However, inherent limitations, the use of highly attenuated/laboratory-adapted RSV strains and the continued evolutionary adaptation of RSV limits extrapolation of results to present-day vaccine testing. With advances in technology, it is now possible to perform more detailed investigations of human mucosal immunity against RSV in experimentally infected adults and, more recently, older adults to optimise the design of vaccines and novel therapies. These studies identified defects in RSV-induced humoral and CD8+ T cell immunity that may partly explain susceptibility to recurrent RSV infection. We discuss the insights from human infection challenge models, ethical and logistical considerations, potential benefits, and role in streamlining and accelerating novel antivirals and vaccines against RSV. Finally, we consider how human challenges might be extended to include relevant at-risk populations.

Nanoparticles and Antiviral Vaccines

Viruses have threatened human lives for decades, causing both chronic and acute infections accompanied by mild to severe symptoms. During the long journey of confrontation, humans have developed intricate immune systems to combat viral infections. In parallel, vaccines are invented and administrated to induce strong protective immunity while generating few adverse effects. With advancements in biochemistry and biophysics, different kinds of vaccines in versatile forms have been utilized to prevent virus infections, although the safety and effectiveness of these vaccines are diverse from each other. In this review, we first listed and described major pathogenic viruses and their pandemics that emerged in the past two centuries. Furthermore, we summarized the distinctive characteristics of different antiviral vaccines and adjuvants. Subsequently, in the main body, we reviewed recent advances of nanoparticles in the development of next-generation vaccines against influenza viruses, coronaviruses, HIV, hepatitis viruses, and many others. Specifically, we described applications of self-assembling protein polymers, virus-like particles, nano-carriers, and nano-adjuvants in antiviral vaccines. We also discussed the therapeutic potential of nanoparticles in developing safe and effective mucosal vaccines. Nanoparticle techniques could be promising platforms for developing broad-spectrum, preventive, or therapeutic antiviral vaccines.

Dynamics and Viability of Airborne Respiratory Syncytial Virus under Various Indoor Air Conditions

The factors governing the viability of airborne viruses embedded within respiratory particles are not well understood. This study aimed to investigate the relative humidity (RH)-dependent viability of airborne respiratory syncytial virus (RSV) in simulated respiratory particles suspended in various indoor air conditions. We tested airborne RSV viability in three static indoor air conditions, including sub-hysteresis (RH < 39%), hysteresis (39% < RH < 65%), and super-hysteresis (RH > 65%) air as well as in three dynamic indoor air conditions, including the transitions between the static conditions. The dynamic conditions were hysteresis → super-hysteresis → hysteresis, sub-hysteresis → hysteresis, and super-hysteresis → hysteresis. We found that after 45 min of particle aging in static conditions, the viability of RSV in sub-hysteresis, hysteresis, and super-hysteresis air was 0.72% ± 0.06%, 0.03% ± 0.006%, and 0.27% ± 0.008%, respectively. After 45 min of aging in dynamic conditions, the RSV viability decreased for particles that remained in a liquid (deliquesced) state during aging when compared with particles in a solid (effloresced) state. The decreased viability of airborne RSV for deliquesced particles is consistent with prolonged exposure to elevated aqueous solutes. These results represent the first measurements of the survival of airborne RSV over particle aging time, with equal viability in low, intermediate, and high RHs at 5 and 15 min and a V-shaped curve after 45 min.

Bivalent vaccines effectively protect mice against influenza A and respiratory syncytial viruses

Influenza and Respiratory Syncytial virus (RSV) infections together contribute significantly to the burden of acute lower respiratory tract infections. Despite the disease burden, no approved RSV vaccine is available. While approved vaccines are available for influenza, seasonal vaccination is required to maintain protection. In addition to both being respiratory viruses, they follow a common seasonality, which warrants the necessity for a concerted vaccination approach. Here, we designed bivalent vaccines by utilizing highly conserved sequences, targeting both influenza A and RSV, as either a chimeric antigen or individual antigens separated by a ribosome skipping sequence. These vaccines were found to be effective in protecting the animals from challenge by either virus, with mechanisms of protection being substantially interrogated in this communication.

Evaluation of intentions to get vaccinated against influenza, COVID 19, pertussis and to get a future vaccine against respiratory syncytial virus in pregnant women

INTRODUCTION

Pregnant women (PW) are at increased risk of complications due to seasonal influenza and Covid-19. Immunization during pregnancy against pertussis and respiratory syncytial virus (RSV) protects newborns from severe diseases. Our aim was to assess intentions to get vaccinated against seasonal influenza, COVID-19, pertussis and RSV in PW and to identify factors associated with intentions.

METHODS

Cross-sectional survey in PW followed at a University Hospital in France assessing their knowledge, and attitudes toward vaccination against influenza, Covid-19, and RSV during pregnancy. Primary outcome was intention to receive each vaccine or potential vaccine. Univariable and multivariable analysis were carried out to identify factors associated with intentions to get vaccinated for each vaccine.

RESULTS

Among the 1199 PW followed during the study period, 310 completed the questionnaire. Intentions to get vaccinated were respectively 43.9 %, 36.8 %, 36.1 % and 39.4 % against influenza, Covid-19, pertussis and RSV. Overall confidence in vaccines using 5C-model, recommendation by a healthcare professional (HCP), good knowledge about diseases and vaccines and previous influenza vaccination were associated with flu vaccine acceptance with respective adjusted odds ratios and 95 % Confidence Intervals (aOR) 1.69 (1.09-2.61) by one-point increase in confidence score, 4.89 (2.24-10.7), 1.56 by one-point increase in knowledge score (1.26-1.93), 13.5 and (5.3-34.3). Confidence was also associated with Covid-19 and RSV vaccine acceptance with respective aOR and 95 % CI 2.63 (1.7-4.07) and 1.92 (1.3-2.84). For pertussis, previous flu vaccination or pertussis vaccination in the last 5 years were predictors of pertussis vaccine acceptance during the pregnancy with respective aOR and 95 % CI 1.97 (1.1-3.84) and 2.9 (1.6-5.18).

CONCLUSION

Confidence is associated with seasonal influenza, COVID-19 and RSV vaccines acceptance in pregnant women. Receiving a recommendation from a HCP was strongly associated with acceptance of influenza vaccine. Recent vaccination against pertussis was not a barrier to pertussis vaccine acceptance during pregnancy.

Molecular epidemiology and characteristics of respiratory syncytial virus among hospitalized children in Guangzhou, China

BACKGROUND

Human respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infection and hospitalization, especially in children. Highly mutagenic nature and antigenic diversity enable the RSV to successfully survive in human population. We conducted a molecular epidemiological study during 2017-2021 to investigate the prevalence and genetic characteristics of RSV.

METHODS

A total of 6499 nasopharyngeal (NP) swabs were collected from hospitalized children at Department of Pediatrics, Guangdong Provincial Hospital of Traditional Chinese Medicine, Guangzhou, Guangdong, China. All NP swab specimens were preliminary screened for common respiratory viruses and then tested for RSV using specific PCR assays. Partial G genes of RSV were amplified for phylogenetic analysis and genetic characterization.

RESULTS

The overall detection rate for common respiratory viruses was 16.12% (1048/6499). Among those, 405 specimens (6.20%, 405/6499) were found positive for RSV. The monthly distribution of RSV and other respiratory viruses was variable, and the highest incidence was recorded in Autumn and Winter. Based on the sequencing of hypervariable region of G gene, 93 RSV sequences were sub-grouped into RSV-A (56, 60.2%) and RSV-B (37, 39.8%). There was no coinfection of RSV-A and RSV-B in the tested samples. Phylogenetic analysis revealed that RSV-A and RSV-B strains belonged to ON1 and BA9 genotypes respectively, indicating predominance of these genotypes in Guangzhou. Several substitutions were observed which may likely change the antigenicity and pathogenicity of RSV. Multiple glycosylation sites were noticed, demonstrating high selection pressure on these genotypes.

CONCLUSION

This study illustrated useful information about epidemiology, genetic characteristics, and circulating genotypes of RSV in Guangzhou China. Regular monitoring of the circulating strains of RSV in different parts of China could assist in the development of more effective vaccines and preventive measures.

Respiratory syncytial virus in pediatric patients with severe acute respiratory infections in Senegal: findings from the 2022 sentinel surveillance season

In 2022, many regions around the world experienced a severe respiratory syncytial virus (RSV) epidemic with an earlier-than-usual start and increased numbers of paediatric patients in emergency departments. Here we carried out this study to describe the epidemiology and genetic characteristics of RSV infection in patients hospitalized with severe acute respiratory infections in 2022. Samples were tested for RSV by multiplex real time reverse transcription polymerase chain reaction. Subsequently, a subset of RSV positive samples was selected for NGS sequencing. RSV was detected in 16.04%, among which RSV-A was confirmed in 7.5% and RSV-B in 76.7%. RSV infection were more identified in infants aged ≤ 11 months (83.3%) and a shift in the circulation pattern was observed, with highest incidences between September-November. Phylogenetic analyses revealed that all RSV-A strains belonged to GA2.3.5 genotype and all RSV-B strains to GB5.0.5a genotype. Three putative N-glycosylation sites at amino acid positions 103, 135, 237 were predicted among RSV-A strains, while four N-linked glycosylation sites at positions 81, 86, 231 and 294 were identified in RSV-B strains. Globally, our findings reveal an exclusive co-circulation of two genetic lineages of RSV within the pediatric population in Senegal, especially in infants aged ≤ 11 months.

Adjuvant-dependent effects on the safety and efficacy of inactivated SARS-CoV-2 vaccines during heterologous infection by a SARS-related coronavirus

Inactivated whole virus SARS-CoV-2 vaccines adjuvanted with aluminum hydroxide (Alum) are among the most widely used COVID-19 vaccines globally and have been critical to the COVID-19 pandemic response. Although these vaccines are protective against homologous virus infection in healthy recipients, the emergence of novel SARS-CoV-2 variants and the presence of large zoonotic reservoirs provide significant opportunities for vaccine breakthrough, which raises the risk of adverse outcomes including vaccine-associated enhanced respiratory disease (VAERD). To evaluate this possibility, we tested the performance of an inactivated SARS-CoV-2 vaccine (iCoV2) in combination with Alum against either homologous or heterologous coronavirus challenge in a mouse model of coronavirus-induced pulmonary disease. Consistent with human results, iCoV2 + Alum protected against homologous challenge. However, challenge with a heterologous SARS-related coronavirus, Rs-SHC014-CoV (SHC014), up to at least 10 months post-vaccination, resulted in VAERD in iCoV2 + Alum-vaccinated animals, characterized by pulmonary eosinophilic infiltrates, enhanced pulmonary pathology, delayed viral clearance, and decreased pulmonary function. In contrast, vaccination with iCoV2 in combination with an alternative adjuvant (RIBI) did not induce VAERD and promoted enhanced SHC014 clearance. Further characterization of iCoV2 + Alum-induced immunity suggested that CD4+ T cells were a major driver of VAERD, and these responses were partially reversed by re-boosting with recombinant Spike protein + RIBI adjuvant. These results highlight potential risks associated with vaccine breakthrough in recipients of Alum-adjuvanted inactivated vaccines and provide important insights into factors affecting both the safety and efficacy of coronavirus vaccines in the face of heterologous virus infections.

Respiratory Syncytial Virus Vaccines: A Review of the Candidates and the Approved Vaccines

Respiratory syncytial virus (RSV) is responsible for a significant proportion of global morbidity and mortality affecting young children and older adults. In the aftermath of formalin-inactivated RSV vaccine development, the effort to develop an immunizing agent was carefully guided by epidemiologic and pathophysiological evidence of the virus, including various vaccine technologies. The pipeline of RSV vaccine development includes messenger ribonucleic acid (mRNA), live-attenuated (LAV), subunit, and recombinant vector-based vaccine candidates targeting different virus proteins. The availability of vaccine candidates of various technologies enables adjustment to the individualized needs of each vulnerable age group. Arexvy® (GSK), followed by Abrysvo® (Pfizer), is the first vaccine available for market use as an immunizing agent to prevent lower respiratory tract disease in older adults. Abrysvo is additionally indicated for the passive immunization of infants by maternal administration during pregnancy. This review presents the RSV vaccine pipeline, analyzing the results of clinical trials. The key features of each vaccine technology are also mentioned. Currently, 24 vaccines are in the clinical stage of development, including the 2 licensed vaccines. Research in the field of RSV vaccination, including the pharmacovigilance methods of already approved vaccines, promotes the achievement of successful prevention.

Fc-mediated functions of nirsevimab complement direct respiratory syncytial virus neutralization but are not required for optimal prophylactic protection

Introduction

Nirsevimab is an extended half-life (M252Y/S254T/T256E [YTE]-modified) monoclonal antibody to the pre-fusion conformation of the respiratory syncytial virus (RSV) Fusion protein, with established efficacy in preventing RSV-associated lower respiratory tract infection in infants for the duration of a typical RSV season. Previous studies suggest that nirsevimab confers protection via direct virus neutralization. Here we use preclinical models to explore whether fragment crystallizable (Fc)-mediated effector functions contribute to nirsevimab-mediated protection.

Methods

Nirsevimab, MEDI8897* (i.e., nirsevimab without the YTE modification), and MEDI8897*-TM (i.e., MEDI8897* without Fc effector functions) binding to Fc γ receptors (FcγRs) was evaluated using surface plasmon resonance. Antibody-dependent neutrophil phagocytosis (ADNP), antibody-dependent cellular phagocytosis (ADCP), antibody-dependent complement deposition (ADCD), and antibody-dependent cellular cytotoxicity (ADCC) were assessed through in vitro and ex vivo serological analyses. A cotton rat challenge study was performed with MEDI8897* and MEDI8897*-TM to explore whether Fc effector functions contribute to protection from RSV.

Results

Nirsevimab and MEDI8897* exhibited binding to a range of FcγRs, with expected reductions in FcγR binding affinities observed for MEDI8897*-TM. Nirsevimab exhibited in vitro ADNP, ADCP, ADCD, and ADCC activity above background levels, and similar ADNP, ADCP, and ADCD activity to palivizumab. Nirsevimab administration increased ex vivo ADNP, ADCP, and ADCD activity in participant serum from the MELODY study (NCT03979313). However, ADCC levels remained similar between nirsevimab and placebo. MEDI8897* and MEDI8897*-TM exhibited similar dose-dependent reduction in lung and nasal turbinate RSV titers in the cotton rat model.

Conclusion

Nirsevimab possesses Fc effector activity comparable with the current standard of care, palivizumab. However, despite possessing the capacity for Fc effector activity, data from RSV challenge experiments illustrate that nirsevimab-mediated protection is primarily dependent on direct virus neutralization.

The role of vaccination in COPD: influenza, SARS-CoV-2, pneumococcus, pertussis, RSV and varicella zoster virus

Exacerbations of COPD are associated with worsening of the airflow obstruction, hospitalisation, reduced quality of life, disease progression and death. At least 70% of COPD exacerbations are infectious in origin, with respiratory viruses identified in approximately 30% of cases. Despite long-standing recommendations to vaccinate patients with COPD, vaccination rates remain suboptimal in this population.Streptococcus pneumoniae is one of the leading morbidity and mortality causes of lower respiratory tract infections. The Food and Drug Administration recently approved pneumococcal conjugate vaccines that showed strong immunogenicity against all 20 included serotypes. Influenza is the second most common virus linked to severe acute exacerbations of COPD. The variable vaccine efficacy across virus subtypes and the impaired immune response are significant drawbacks in the influenza vaccination strategy. High-dose and adjuvant vaccines are new approaches to tackle these problems. Respiratory syncytial virus is another virus known to cause acute exacerbations of COPD. The vaccine candidate RSVPreF3 is the first authorised for the prevention of RSV in adults ≥60 years and might help to reduce acute exacerbations of COPD. The 2023 Global Initiative for Chronic Lung Disease report recommends zoster vaccination to protect against shingles for people with COPD over 50 years.

Immunogenicity of an AS01-adjuvanted respiratory syncytial virus prefusion F (RSVPreF3) vaccine in animal models

Respiratory syncytial virus (RSV) causes a high disease burden in older adults. An effective vaccine for this RSV-primed population may need to boost/elicit robust RSV-neutralizing antibody responses and recall/induce RSV-specific T cell responses. To inform the selection of the vaccine formulation for older adults, RSVPreF3 (RSV fusion glycoprotein engineered to maintain the prefusion conformation) with/without AS01 adjuvant was evaluated in mice and bovine RSV infection-primed cattle. In mice, RSVPreF3/AS01 elicited robust RSV-A/B-specific neutralization titers and RSV F-specific polyfunctional CD4+ T cell responses exceeding those induced by non-adjuvanted RSVPreF3. In primed bovines, RSVPreF3/AS01 tended to induce higher pre-/post-vaccination fold-increases in RSV-A/B-specific neutralization titers relative to non-adjuvanted and Alum-adjuvanted RSVPreF3 formulations, and elicited higher RSV F-specific CD4+ T cell frequencies relative to the non-adjuvanted vaccine. Though AS01 adjuvanticity varied by animal species and priming status, RSVPreF3/AS01 elicited/boosted RSV-A/B-specific neutralization titers and RSV F-specific CD4+ T cell responses in both animal models, which supported its further clinical evaluation as prophylactic candidate vaccine for older adults.

Characteristics of clinical trials of influenza and respiratory syncytial virus registered in ClinicalTrials.gov between 2014 and 2021

The randomized clinical trial (RCT) is the ideal and mandatory type of study to verify the effect and safety of a drug. Our aim is to examine the fundamental characteristics of interventional clinical trials on influenza and respiratory syncytial virus (RSV). This is a cross-sectional study of RCTs on influenza and RSV in humans between 2014 and 2021 registered in ClinicalTrials.gov. A total of 516 studies were identified: 94 for RSV, 423 for influenza, and 1 for both viruses. There were 51 RCTs of RSV vaccines (54.3%) and 344 (81.3%) for influenza virus vaccines (p < 0.001). Twelve (12.8%) RCTs for RSV were conducted only with women, and 6 were conducted only with pregnant women; for RCTs for influenza, 4 (0.9%) and 3, respectively. For RSV, 29 (31%) of the RCTs were exclusive to people under 5 years of age, and 21 (5%) for influenza virus (p < 0.001). For RSV, there are no RCTs exclusively for people older than or equal to 65 years and no phase 4 trials. RCTs on influenza virus and RSV has focused on vaccines. For the influenza virus, research has been consolidated, and for RSV, research is still in the development phase and directed at children and pregnant women.