Daily Respiratory Research Analysis
Three papers advance respiratory medicine across vaccine design, COVID-19 booster policy, and chronic airflow limitation risk stratification. A structural study maps conserved antigenic sites on RSV G targeted by broadly reactive human antibodies, informing next-generation prophylactics. Large-scale real-world data show annual variant-targeted COVID-19 boosters reduce severe disease for about six months, while a multinational cohort links baseline bronchodilator responsiveness to future chronic
Summary
Three papers advance respiratory medicine across vaccine design, COVID-19 booster policy, and chronic airflow limitation risk stratification. A structural study maps conserved antigenic sites on RSV G targeted by broadly reactive human antibodies, informing next-generation prophylactics. Large-scale real-world data show annual variant-targeted COVID-19 boosters reduce severe disease for about six months, while a multinational cohort links baseline bronchodilator responsiveness to future chronic airflow obstruction.
Research Themes
- Structure-guided RSV vaccine antigen design
- Effectiveness and durability of variant-targeted COVID-19 boosters
- Predictive markers for incident chronic airflow obstruction
Selected Articles
1. Structures of respiratory syncytial virus G bound to broadly reactive antibodies provide insights into vaccine design.
Using cryo-EM structures of three broadly reactive human monoclonal antibodies bound to RSV G, the authors define conserved, conformational epitopes that comprise two non-overlapping antigenic sites. Sequence and competition analyses suggest antigenic site flexibility fosters diverse germline usage, informing designs to elicit broadly reactive anti-G responses.
Impact: Delivers precise structural blueprints of conserved RSV G antigenic sites targeted by protective human antibodies, opening a complementary vaccine pathway beyond F-only strategies.
Clinical Implications: Guides the rational design of RSV vaccines or monoclonals that target G, potentially improving breadth and durability of protection and complementing F-based products now in use.
Key Findings
- Cryo-EM structures of three human broadly reactive anti-RSV G antibodies revealed conserved, conformational epitopes comprising two non-overlapping antigenic sites.
- Binding competition and structural data identified a highly conserved region on G with dual antigenic topology.
- Antibody sequence analyses indicate antigenic site flexibility that may promote elicitation of diverse antibody germlines, supporting broadly reactive vaccine design.
Methodological Strengths
- High-resolution structural definition of antibody–antigen complexes enabling epitope mapping
- Convergent evidence from binding competition, structural biology, and sequence analyses
Limitations
- Preclinical mechanistic study without direct clinical efficacy testing
- Scope limited to three monoclonal antibodies and selected G regions
Future Directions: Design and immunogenicity testing of G-based or G+F combination immunogens; evaluation of breadth, durability, and protection in animal models and early human trials.
Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract disease in infants and older adults. The attachment glycoprotein (RSV G) binds to the chemokine receptor CX3CR1 to promote viral entry and modulate host immunity. Antibodies against RSV G are a known correlate of protection. Previously, several broadly reactive, high-affinity anti-RSV G human monoclonal antibodies were isolated from RSV-exposed individuals and were shown to be protective in vitro and in vivo. Here, we determined the structures of three of these antibodies in complex with RSV G and defined distinct conformational epitopes comprised of highly conserved RSV G residues. Binding competition and structural studies demonstrated that this highly conserved region displays two non-overlapping antigenic sites. Analyses of anti-RSV G antibody sequences reveal that antigenic site flexibility may promote the elicitation of diverse antibody germlines. Together, these findings provide a foundation for next-generation RSV prophylactics, and they expand concepts in vaccine design for the elicitation of germline lineage-diverse, broadly reactive, high-affinity antibodies.
2. Annual Variant-Targeted Vaccination to Prevent Severe COVID-19 in Cohorts With Vaccine-Derived and Hybrid Immunity.
In a target trial emulation of 1.58 million US Veterans, a variant-targeted mRNA booster conferred modest but significant protection against COVID-19 pneumonia hospitalization (rVE 29% with vaccine-derived immunity; 38% with hybrid immunity), sustained for 0–6 months but not 6–12 months. Benefits were consistent across pre-XBB and XBB eras and for in-hospital severe illness.
Impact: Provides high-quality real-world effectiveness and durability estimates to guide booster timing and expectations in populations with prior vaccination and/or infection.
Clinical Implications: Support annual variant-targeted boosters with emphasis on high-risk groups, recognizing benefit primarily within 6 months; consider timing strategies before anticipated surges.
Key Findings
- Variant-targeted mRNA booster reduced hospitalization due to COVID-19 pneumonia with rVE 29% (vaccine-derived immunity) and 38% (hybrid immunity).
- Protection was significant in the first 0–6 months but not 6–12 months post-booster, across pre-XBB and XBB eras.
- Similar protective effects were observed for in-hospital severe illness.
Methodological Strengths
- Target trial emulation with large-scale propensity score matching and time-updated weekly matching
- Robust outcomes (hospitalization due to pneumonia; in-hospital severe illness) and stratification by prior infection era
Limitations
- Observational design with potential residual confounding and misclassification in EHRs
- Generalizability may be limited (Veterans, older and predominantly male population)
Future Directions: Optimize booster timing and frequency (e.g., semiannual for highest risk), evaluate variant-updated formulations, and assess heterologous strategies to extend durability.
BACKGROUND: Current coronavirus disease 2019 (COVID-19) vaccine recommendations in the United States (US) provide guidance for adults to receive at least annual variant-targeted vaccination. We sought to estimate the strength and durability of protection from annual variant-targeted vaccination against severe COVID-19 illness in individuals with vaccine-derived and hybrid immunity. METHODS: We emulated a target trial using an electronic health record-based, propensity score-matched (1:1) cohort of US Veterans. Booster-vaccinated adults were eligible for a variant-targeted messenger RNA (mRNA) booster starting 1 September 2022. Matched sets of those who did and did not receive the variant-targeted booster dose were identified on a weekly basis, and the cohort was followed until 31 August 2023. Outcomes were hospitalization due to COVID-19 pneumonia and in-hospital severe illness. We fit Cox models, overall and stratified by last documented severe acute respiratory syndrome coronavirus 2 infection (pre-Omicron, Omicron), to estimate relative vaccine effectiveness (rVE). RESULTS: The propensity score-matched cohort consisted of 1 576 626 COVID-19 booster-vaccinated adults. Estimates of rVE from variant-targeted mRNA booster against hospitalization due to COVID-19 pneumonia were significant and similar in the cohort with vaccine-derived immunity (rVE, 29% [95% confidence interval {CI}, 25%-34%]) and cohort with hybrid immunity (rVE, 38% [95% CI, 27%-47%]). These protective gains were significant from 0 to 6 months but not 6 to 12 months after vaccination and during pre-XBB and XBB variant eras. Findings were similar for in-hospital severe illness. CONCLUSIONS: In cohorts with vaccine-derived and hybrid immunity, modest but significant gains in protection against hospitalization and severe COVID-19 illness were conferred by the annual variant-targeted booster dose but not sustained beyond 6 months.
3. Bronchodilator responsiveness and future chronic airflow obstruction: a multinational longitudinal study.
In the multinational BOLD cohort (n=3,701; mean follow-up 9.1 years), baseline bronchodilator responsiveness independently predicted incident chronic airflow obstruction (RR 1.36), with stronger associations in women (RR 1.45) and never-smokers (RR 1.48). Findings suggest BDR has prognostic value beyond asthma diagnosis.
Impact: Identifies a simple, widely available physiological marker that stratifies risk for incident airflow limitation, potentially informing surveillance and early intervention strategies.
Clinical Implications: Consider integrating BDR status into risk assessment for progression to chronic airflow obstruction, especially in women and never-smokers; prompts targeted monitoring and preventive measures.
Key Findings
- Baseline bronchodilator responsiveness was associated with a 36% higher risk of incident chronic airflow obstruction over ~9 years.
- Association was stronger in women (RR 1.45) and in never-smokers (RR 1.48).
- Prospective, multinational design with standardized pre- and post-bronchodilator spirometry.
Methodological Strengths
- Longitudinal, population-based cohort with standardized spirometry and long follow-up
- Use of contemporary ATS/ERS 2022 definition for bronchodilator responsiveness
Limitations
- Potential attrition and unmeasured confounding over long follow-up
- Abstract truncation does not detail exact FEV1/FVC thresholds used for chronic airflow obstruction
Future Directions: Replicate in other cohorts; assess if BDR-guided monitoring or interventions (e.g., smoking cessation reinforcement, inhaled therapy) reduce progression to airflow limitation.
BACKGROUND: Bronchodilator responsiveness testing is mainly used for diagnosing asthma. We aimed to investigate whether it is associated with progression to chronic airflow obstruction over time. METHODS: The multinational Burden of Obstructive Lung Disease cohort study surveyed adults, aged 40 years and above, at baseline and followed them up after a mean of 9.1 years. Recruitment took place between January 2, 2003 and December 26, 2016. Follow-up measurements were collected between January 29, 2019 and October 24, 2021. On both occasions, study participants provided information on respiratory symptoms, health status and several environmental and lifestyle exposures. They also underwent pre- and post-bronchodilator spirometry. We defined bronchodilator responsiveness at baseline using the American Thoracic Society and European Respiratory Society (ATS/ERS) 2022 definition, and the presence of chronic airflow obstruction at follow-up as a post-bronchodilator forced expiratory volume in 1 s to forced vital capacity ratio (FEV FINDINGS: We analysed data from 3701 adults with 56% being women. Compared to those without bronchodilator responsiveness at baseline, those with bronchodilator responsiveness had 36% increased risk of developing chronic airflow obstruction (RR: 1.36, 95%CI 1.04, 1.80). This effect was stronger in women (RR: 1.45, 95%CI 1.09, 1.91) than men (RR: 1.07, 95%CI 0.51, 2.24). Never smokers with bronchodilator responsiveness also were at greater risk of incident chronic airflow obstruction (RR: 1.48, 95%CI 1.01, 2.20). INTERPRETATION: Bronchodilator responsiveness appears to be a risk factor for incident chronic airflow obstruction. It is important that future studies in other large population-based cohorts replicate these findings. FUNDING: National Heart and Lung Institute, UK Medical Research Council, and Wellcome Trust.