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Background: Antibodies to SARS-CoV-2 are essential for protection or reduction in severity of subsequent disease. We studied antibody responses to spike protein receptor-binding domain (S1-RBD) and nucleocapsid (N) in a population-based sample of COVID-19 cases in Costa Rica.
Methods: As part of the RESPIRA study, we selected an age-stratified random sample of PCR-confirmed COVID-19 cases diagnosed from March 2020 to July 2021. Antibodies were determined with multiplex serology in 794 unvaccinated subjects diagnosed 3 days to 17 months before recruitment to investigate immune response to natural infection. In addition, neutralizing antibodies were determined in 136 randomly selected participants. We estimated antibody positivity and GMTs by time since diagnosis and explored determinants using multivariate regression.
Results: Most participants tested 15-29 days after PCR diagnosis were seropositive for N (90%) and S1-RBD antibodies (96%) and had the highest GMTs for both antibodies. Only 42% of subjects tested one year after infection were seropositive for N antibodies, compared to 97% for S1-RBD. GMTs for neutralizing antibodies peaked 15-89 days after infection and declined but remained positive for 95% of subjects thereafter. In multivariate models, antibodies were significantly higher among men and increased with age and severity of the clinical presentation. The correlation of multiplex and neutralizing antibodies was high (0.72 [95% CI = 0.63-0.79]) and stronger among women.
Conclusions: A robust immune response against N and S1-RBD is elicited by COVID-19 a few days after infection. While S1-RBD antibodies are present after > 1 year, N antibodies decline significantly. Antibody levels are higher in men and increase with age and severity of disease. The different immune response patterns by sex warrant further investigation.
Trial Registration: RESPIRA Study ClinicalTrials.gov ID: NCT04537338 (3 September 2020).
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http://dx.doi.org/10.1186/s12879-025-10742-8 | DOI Listing |
PLoS One
September 2025
Agencia Costarricense de Investigaciones Biomédicas-Fundación INCIENSA (ACIB-FUNIN), San José, Costa Rica.
Previous SARS-CoV-2 research indicates that antibody levels and corresponding neutralization potential increase with additional exposures (comprising vaccination or infection), and that hybrid immunity resulting from combined vaccination and natural infection is more robust than either alone. However, it is unclear whether or how antibody levels increase or eventually plateau with repeated exposures and how SARS-CoV-2 exposure differs by sex or other demographic factors. Research regarding the association of antibody production with neutralization potential is also limited.
View Article and Find Full Text PDFRespir Med
August 2025
Department of Pulmonary and Critical Care Medicine, Mayo Clinic, 4500 San Pablo Rd S, Jacksonville, FL, 32224, USA. Electronic address:
Introduction: Pulmonary arterial hypertension (PAH) is a rare and progressive disease associated with significant morbidity and mortality. Prostacyclins, including treprostinil, are a mainstay of PAH treatment, particularly in patients with intermediate to high risk of death. Following the approval of treprostinil inhalation solution for PAH, treprostinil dry powder inhaler (DPI) was developed as a small, portable, low-maintenance device to improve patient experience.
View Article and Find Full Text PDFAdv Ther
August 2025
Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK.
Introduction: Seralutinib is an inhaled tyrosine kinase inhibitor targeting platelet-derived growth factor receptor (PDGFR) α/β, colony stimulating factor 1 receptor (CSF1R), and mast/stem cell growth factor receptor kit (c-KIT) kinases. TORREY, a phase 2, double-blind, randomized, placebo-controlled study of seralutinib in pulmonary arterial hypertension (PAH), met its primary endpoint, demonstrating a significant reduction in pulmonary vascular resistance (PVR) over placebo after 24 weeks (NCT04456998; EudraCT 2019-002669-37). We present results (as of December 5, 2024) from an open-label extension (OLE) study evaluating long-term safety, tolerability, and efficacy of seralutinib in adults with PAH (NCT04816604).
View Article and Find Full Text PDFInt J Chron Obstruct Pulmon Dis
August 2025
Departamento Médico, Chiesi, España.
Purpose: Chronic respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma, pose a significant health risk due to the increasingly pronounced rise in its prevalence, associated complications and impact on patients' quality of life. The aim of this study is to analyse the needs of patients with COPD and asthma throughout their patient journey.
Patients And Methods: To this end, a qualitative and cross-sectional study was conducted based on interviews and focus groups.
Eur J Appl Physiol
August 2025
Department of Physiotherapy, Cardiopulmonary Physiotherapy Laboratory (LACAP), Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil.
Exercise intolerance is a cardinal symptom in patients with heart failure (HF), and cardiopulmonary exercise testing (CPET) is the gold standard method for its assessment. The treadmill and cycle ergometers (upright and recumbent) are used in clinical practice for tracking disease progression and risk stratification, therefore, understanding the physiological differences related to ergometer is important. The aim of this study was to compare the physiological responses to exercise on treadmill and recumbent cycle ergometer in patients with HF with reduced ejection fraction (HFrEF) using a linear ramp protocol matched with controlled work rate (WR) profiles.
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