Daily Respiratory Research Analysis
Three impactful respiratory studies stand out today: (1) a Science report shows that pre-exposure prophylaxis with a broadly neutralizing antibody (MEDI8852) robustly protects macaques against severe H5N1 influenza; (2) a randomized ED imaging analysis demonstrates ultra–low-dose chest CT improves true-positive detection of pneumonia versus chest X-ray, with trade-offs in false positives; and (3) a large systematic analysis reveals ~6-week local-level variability in RSV seasonality, driven by me
Summary
Three impactful respiratory studies stand out today: (1) a Science report shows that pre-exposure prophylaxis with a broadly neutralizing antibody (MEDI8852) robustly protects macaques against severe H5N1 influenza; (2) a randomized ED imaging analysis demonstrates ultra–low-dose chest CT improves true-positive detection of pneumonia versus chest X-ray, with trade-offs in false positives; and (3) a large systematic analysis reveals ~6-week local-level variability in RSV seasonality, driven by meteorological and sociodemographic factors, informing immunization timing.
Research Themes
- Pre-exposure antibody prophylaxis for pandemic influenza
- Emergency department imaging optimization for pneumonia diagnosis
- Local-level RSV seasonality and immunization timing
Selected Articles
1. Pre-exposure antibody prophylaxis protects macaques from severe influenza.
In a controlled nonhuman primate challenge, pre-exposure prophylaxis with the broadly neutralizing antibody MEDI8852 prevented severe disease and death after aerosolized H5N1 infection. Protection was dose-dependent and independent of Fc effector functions at the tested dose; ≥10 mg/kg recipients had negligible respiratory impairment compared to unprotected controls.
Impact: Provides compelling preclinical evidence that bnAb prophylaxis can avert severe disease from highly pathogenic avian influenza, informing pandemic preparedness strategies.
Clinical Implications: Supports development of long-acting bnAb prophylaxis for high-risk exposures and stockpiling for pandemic response, with potential to protect healthcare workers and vulnerable populations.
Key Findings
- Pre-exposure MEDI8852 protected cynomolgus macaques from severe disease and fatality after aerosolized H5N1 challenge.
- Protection was antibody dose-dependent; ≥10 mg/kg resulted in negligible respiratory impairment.
- At the tested dose, efficacy was independent of Fc-mediated effector functions.
Methodological Strengths
- Rigorous nonhuman primate aerosol challenge model with dose–response assessment
- Functional respiratory outcomes and Fc-function independence evaluated
Limitations
- Sample size not reported in the abstract and limited to a preclinical NHP model
- Pre-exposure prophylaxis may not translate directly to post-exposure treatment scenarios
Future Directions: Evaluate safety, pharmacokinetics, and efficacy of long-acting bnAb prophylaxis in humans; explore combination bnAbs and half-life–extended formats for broader and durable protection.
Influenza virus pandemics and seasonal epidemics have claimed countless lives. Recurrent zoonotic spillovers of influenza viruses with pandemic potential underscore the need for effective countermeasures. In this study, we show that pre-exposure prophylaxis with broadly neutralizing antibody (bnAb) MEDI8852 is highly effective in protecting cynomolgus macaques from severe disease caused by aerosolized highly pathogenic avian influenza H5N1 virus infection. Protection was antibody dose-dependent yet independent of Fc-mediated effector functions at the dose tested. Macaques receiving MEDI8852 at 10 milligrams per kilogram or higher had negligible impairment of respiratory function after infection, whereas control animals were not protected from severe disease and fatality. Given the breadth of MEDI8852 and other bnAbs, we anticipate that protection from unforeseen pandemic influenza A viruses is achievable.
2. Diagnostic accuracy of ultra-low-dose chest CT vs chest X-ray for acute non-traumatic pulmonary diseases.
In a secondary analysis of the randomized OPTIMACT trial (n≈2312), ULDCT increased true-positive detection and reduced false negatives for pneumonia and other LRTIs versus CXR, at the cost of more false positives, with comparable PPVs. Radiologist diagnostic confidence was higher with ULDCT; however, CXR detected pulmonary congestion more often.
Impact: Directly informs ED imaging pathways by quantifying the diagnostic trade-offs between ULDCT and CXR for common acute pulmonary presentations.
Clinical Implications: Adopting ULDCT for selected ED patients can improve pneumonia/LRTI detection and diagnostic certainty. Systems should mitigate increased false positives (e.g., clinical decision rules) and use CXR when pulmonary congestion is the primary concern.
Key Findings
- For pneumonia, ULDCT yielded more true positives (ratio 1.50) and fewer false negatives (0.61) than CXR, but more false positives (1.75); PPVs were similar.
- Similar advantages for ULDCT were seen for other LRTIs; radiologist certainty was higher with ULDCT.
- Pulmonary congestion was detected less often by ULDCT than CXR, with fewer TPs and FPs.
Methodological Strengths
- Randomized allocation within a large prospective ED trial with day-28 reference diagnosis
- Comprehensive evaluation of TP/FP/FN and diagnostic confidence
Limitations
- Secondary analysis; increased false positives for infections may prompt downstream testing
- Dose/radiation considerations and resource availability for ULDCT in all ED settings
Future Directions: Develop decision pathways to target ULDCT use, integrate clinical/lab predictors to curb false positives, and perform cost-effectiveness and outcome studies across ED populations.
OBJECTIVES: To compare the diagnostic accuracy of ULDCT to CXR for detecting non-traumatic pulmonary diseases at the emergency department (ED) and to study diagnostic confidence levels. METHODS: Secondary analysis of the prospective OPTIMACT trial (2418 ED participants randomly allocated to ULDCT or CXR). Diagnoses at imaging at the ED were compared to the reference diagnosis on day 28. Ratios of positive diagnoses, true positives (TP), false positives (FP), false negatives (FN), and positive predictive values (PPV) were assessed with 95% confidence intervals (CI). The diagnostic confidence levels of the radiologists were studied. RESULTS: One thousand one hundred sixty-one ULDCT participants (mean age, 59 years ± 18 [standard deviation], 587 female) and 1151 CXR participants (mean age, 59 years ± 18 [standard deviation], 561 female) were evaluated. With ULDCT, pneumonia was 1.55 times (95% CI: 1.33-1.80) more often diagnosed at imaging at the ED, with significantly more TP (ratio 1.50; 95% CI: 1.26-1.76) and fewer FN (0.61; 95% CI: 0.37-0.99) but more FP (1.75; 95% CI: 1.19-2.58); a similar pattern was observed for other lower respiratory tract infections (LRTI). Pulmonary congestion was less often observed with ULDCT (0.45; 95% CI: 0.34-0.61), with fewer TP (0.50; 95% CI: 0.34-0.73), and FP (0.40; 95% CI: 0.24-0.65). PPVs were not significantly different. With ULDCT, radiologists were more often certain in diagnosing pneumonia (ULDCT 121/324, 37% vs CXR 48/208, 23%), LRTI (84/192, 44% vs 18/63, 29%), and no established disease (350/382, 92% vs 447/544, 82%). CONCLUSION: Compared to CXR, ULDCT led to more TP but also more FP in detecting pneumonia and LRTI, while fewer TP and FP were found for pulmonary congestion. PPVs were comparable. KEY POINTS: Question Is ultra-low dose CT (ULDCT) more accurate than chest X-ray (CXR) for identifying non-traumatic pulmonary diseases in patients presenting at the ED? Findings ULDCT detects more pulmonary infections in patients presenting at the ED with non-traumatic pulmonary complaints, while CXR detects more pulmonary congestion. Clinical relevance ULDCT is superior to CXR in detecting pneumonia and other LRTI in ED patients, while CXR is superior in detecting pulmonary congestion. ULDCT can be an alternative for CXR in a selected group of patients.
3. Understanding the local-level variations in seasonality of human respiratory syncytial virus infection: a systematic analysis.
Synthesizing 7 studies plus 3 national datasets (Japan, Spain, Scotland; 888,447 cases), this analysis shows local-level RSV season onset can vary by ~6 weeks and offset by ~5 weeks within regions. Meteorological, geographical, and sociodemographic factors jointly explain a large share of onset and offset variability, informing local immunization and resource planning.
Impact: Defines actionable local variability in RSV seasonality with quantified environmental drivers, critical for timing monoclonal antibody/prophylaxis and healthcare surge planning.
Clinical Implications: Supports tailoring timing of nirsevimab/palivizumab and vaccination strategies by locality, using meteorological and demographic data to anticipate RSV onset and optimize resource allocation.
Key Findings
- Across 101 local sites (1995–2020; 888,447 cases), RSV season onset varied by ~6 weeks and offset by ~5 weeks within regions.
- Temperature, humidity, wind, latitude/longitude, income, and population jointly explained 66–84% of onset and 35–49% of offset variability.
- Year-to-year differences were substantial, emphasizing the need for adaptive, local-level planning.
Methodological Strengths
- Multi-level mixed-effects meta-analysis integrating large, site-specific datasets across countries
- Regression modeling with clustered SEs linking environmental and sociodemographic factors to seasonality
Limitations
- Heterogeneity in surveillance definitions and data quality across sites and years
- Explained variability lower for season offset (35–49%), indicating unmeasured drivers
Future Directions: Develop real-time local predictive models integrating weather feeds to guide immunization scheduling; evaluate impact of tailored timing on RSV hospitalizations and health-system load.
BACKGROUND: While previous reports characterised global and regional variations in RSV seasonality, less is known about local variations in RSV seasonal characteristics. This study aimed to understand the local-level variations in RSV seasonality and to explore the role of geographical, meteorological, and socio-demographic factors in explaining these variations. METHODS: We conducted a systematic literature review to identify published studies reporting data on local-level RSV season onset, offset, or duration for at least two local sites. In addition, we included three datasets of RSV activity from Japan, Spain, and Scotland with available site-specific data. RSV season onset, offset, and duration were defined using the annual cumulative proportion method. We estimated between-site variations within a region using the earliest onset, the earliest offset, and the shortest duration of RSV season of that region as the references and synthesised the variations across regions by a multi-level mixed-effects meta-analysis. Using the three datasets from Japan, Spain and Scotland, we applied linear regression models with clustered standard errors to explore the association of geographical, meteorological, and socio-demographic factors with the season onset and offset, respectively. RESULTS: We included 7 published studies identified from the systematic literature search. With the additional 3 datasets, these data sources covered 888,447 RSV-positive cases from 101 local study sites during 1995 to 2020. Local-level variations in RSV season within a region were estimated to be 6 weeks (41 days, 95% CI: 25-57) for season onset, 5 weeks (32 days, 13-50) for season offset, and 6 weeks (40 days, 20-59) for season duration, with substantial differences across years. Multiple factors, such as temperature, relative humidity, wind speed, annual household income, population size, latitude, and longitude, could jointly explain 66% to 84% and 35% to 49% of the variations in season onset and offset, respectively, although their individual effects varied by individual regions. CONCLUSIONS: Local-level variations in RSV season onset could be as much as 6 weeks, which could be influenced by meteorological, geographical, and socio-demographic factors. The reported variations in this study could have important implications for local-level healthcare resources planning and immunisation strategy. TRIAL REGISTRATION: PROSPERO CRD42023482432.