Enflonsia (clesrovimab-cfor) / Merck (MSD) - LARVOL DELTA

Merck…announced today that Health Canada has approved ENFLONSIA (clesrovimab) for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in neonates (newborns) and infants born during or entering their first RSV season (Canada Newswire) - "Health Canada's approval is supported by results from Merck's clinical development program, including the pivotal Phase 2b/3 CLEVER trial (MK‑1654‑004) and the Phase 3 SMART trial (MK‑1654‑007)."

Canada approval • Respiratory Syncytial Virus Infections

The Drug Update: Recent drug approvals, winter 2026 edition. (PubMed, Nurse Pract) - "This article highlights the following new medications and vaccinations: suzetrigine (Journavx); gepotidacin (Blujepa); meningococcal groups A, B, C, W, and Y vaccine (Penmenvy); clesrovimab-cfor (Enflonsia); and acoltremon (Tryptyr). Additionally, this article highlights the recent approval of moderately to severely active Crohn's disease as a new indication for guselkumab (Tremfya)."

Journal • CNS Disorders • Crohn's disease • Dry Eye Disease • Gastroenterology • Immunology • Infectious Disease • Inflammatory Bowel Disease • Meningococcal Infections • Nephrology • Ophthalmology • Pain • Respiratory Diseases • Respiratory Syncytial Virus Infections

Population Pharmacokinetics of Clesrovimab in Preterm and Full-Term Infants. (PubMed, Clin Pharmacol Ther) - "Although body weight, age, and race were identified as statistically significant covariates, the magnitude of the effect of these covariates on clesrovimab exposures was small (< 30%). The results of the population PK modeling support intramuscular administration of clesrovimab for the prevention of respiratory syncytial virus (RSV) disease in all infants, including healthy infants and infants at increased risk for severe RSV disease."

Journal • PK/PD data • Respiratory Diseases • Respiratory Syncytial Virus Infections

Recent developments in pediatric respiratory syncytial virus prevention: The expanding role of monoclonal antibodies. (PubMed, Am J Health Syst Pharm) - "The utility of RSV monoclonal antibodies continues to evolve, with these antibodies offering promising targeted, durable protection against a virus that remains a major cause of morbidity in infants and young children. Ongoing surveillance, real-world evidence, and continued innovation will further refine the role of these agents in clinical practice. Pharmacists play a pivotal role in evaluating appropriate candidates for therapy, navigating payor and formulary requirements, and educating caregivers and healthcare teams on administration, storage, and monitoring."

Journal • Pediatrics • Respiratory Diseases • Respiratory Syncytial Virus Infections

Taxonomy of the Full Health and Societal Value of Maternal Vaccination to Prevent Infant Respiratory Syncytial Virus Disease. (PubMed, Infect Dis Ther) - "It distinguishes among benefits to infants; the mother, parents, caregivers, and household members; the health system; and the broader population, society, and government. Value elements include infant health (including from reduced mortality, severe disease, and long-term complications), reduced health system costs, reduced caregiver burdens, financial risk protection, parental peace of mind, averted parental bereavement, process utility from transference of injection burdens and risks from infant to mother, health and socioeconomic equity, antimicrobial resistance reduction from averted inappropriate antibiotic use, potential enhanced education from reduced long-term sequelae, and potential herd effects."

Journal • Review • Infectious Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Respiratory Syncytial Virus (RSV) Prophylaxis: Clesrovimab and Beyond. (PubMed, J Med Chem) - No abstract available

Journal • Respiratory Diseases

Protecting Our Littlest Patients: A Review of Clesrovimab for RSV Prevention in Infants (ASHP 2025) - No abstract available

Clinical • Review

Polybodies for the treatment of respiratory syncytial virus infection. (PubMed, Drug Discov Today) - "Although current prophylactics, such as palivizumab, nirsevimab, and clesrovimab, which target the RSV F protein, have enhanced early protection, more effective options with broader impact and longer-lasting efficacy are needed. In response to ongoing research efforts to develop new treatments for RSV, nanobodies have emerged as a promising option. Therefore, in this review, we discuss available therapies and explore the potential of nanobodies in treating RSV, with particular emphasis on the importance of polybodies [polyspecific and polyvalent antibodies (PsAbs and PvAbs)] in managing RSV infections."

Journal • Review • Infectious Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Prophylactic monoclonal antibodies against respiratory syncytial virus in early life: An in-depth review of mechanisms of action, failure factors, and future perspectives. (PubMed, Pediatr Allergy Immunol) - "For over two decades, palivizumab was the only monoclonal antibody (mAb) available for prophylaxis, restricted to high-risk groups due to cost and limited duration of protection. Recent advances in structural virology and antibody engineering have led to the emergence of long-acting mAbs, notably nirsevimab and clesrovimab, which offer single-dose seasonal protection and are now shifting RSV prevention strategies from high-risk targeting to universal infant immunization...This review explores the molecular and immunological underpinnings of RSV-targeted mAbs, evaluates current real-world evidence, and outlines future directions-including bispecific antibodies and nanobody-based therapies-that could further transform RSV prophylaxis. Sustained genomic surveillance and a deeper understanding of host immunity will be crucial to preserve the long-term efficacy of these innovations in pediatric infectious disease prevention."

Journal • Review • Infectious Disease • Pediatrics • Pulmonary Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Clesrovimab for the Prevention of Respiratory Syncytial Virus Lower Respiratory Tract Disease in Infants. (PubMed, J Pharm Technol) - " Clesrovimab offers simplified dosing, favorable safety, and potential cost savings compared with palivizumab and nirsevimab. Clesrovimab is a promising addition to RSV prevention strategies, offering effective, safe, and accessible immunization for infants. Ongoing research will clarify its role in high-risk populations and broader clinical use."

Journal • Review • Infectious Disease • Pediatrics • Respiratory Diseases • Respiratory Syncytial Virus Infections

Comparison of the public health impact of RSV disease prevention options for infants: a static decision model of the us birth cohort. (PubMed, Expert Rev Vaccines) - "We compared the impact of these interventions on RSV-LRTD events and costs versus the previous standard-of-practice (SoP; palivizumab-only strategy). RSVpreF maternal vaccination would avert 76,915 RSV-LRTDs including 9,649 hospitalizations, equating to $345 million in total cost savings. While all three interventions are estimated to reduce RSV-LRTD burden in infants, all-infant protection with nirsevimab was estimated to avert more events and associated medical costs for all infant subgroups compared to clesrovimab or RSVpreF."

Journal • Respiratory Diseases • Respiratory Syncytial Virus Infections

Development of a Multidimensional HTA Evaluation for the Introduction of Clesrovimab in Pediatric RSV Prevention: An Integrated Methodological Approach (ISPOR-EU 2025) - "Clesrovimab appears to be a cost-effective option for RSV prevention. The HTA approach supports informed decisions and may promote equitable access and improved outcomes in the neonatal population."

Clinical • Infectious Disease • Pediatrics • Respiratory Diseases • Respiratory Syncytial Virus Infections

Respiratory syncytial virus. What's new in prevention? (PubMed, Semin Fetal Neonatal Med) - "Prevention of RSV lower respiratory tract infections (LRTI) in infants has been limited to general measures and palivizumab, a monoclonal antibody indicated for the highest risk groups...Likewise, novel extended half-life monoclonal antibodies, nirsevimab and the recently approved clesrovimab, opened the possibility of large-scale protection targeted to all infants born during the winter season and those <6 months at the beginning of it. Several RCTs and results from populations adopting nirsevimab prophylaxis demonstrated a large decrease in the incidence of RSV-LRTIs and a great impact in infant public health. Deployment of either strategies or in combination as part of immunization programs can be complement each other even as newer immunologic agents are being introduced."

Journal • Review • Infectious Disease • Pulmonary Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Genetic variability of respiratory syncytial virus and its impact on monoclonal antibody binding sites: a national cross-sectional study during the 2023-2024 season. (PubMed, Int Immunopharmacol) - "This study provides a critical genomic snapshot of RSV in Italy prior to the introduction of vaccines and mAbs. Continuous surveillance is essential for monitoring viral evolution and supporting the long-term effectiveness of future immunization strategies."

Clinical • Journal • Observational data • Infectious Disease • Influenza • Respiratory Diseases • Respiratory Syncytial Virus Infections

Prevalence of Resistance-Associated Mutations in RSV F Protein Against Monoclonal Antibodies Prior to Widespread Implementation: Findings From a Prospective German Pediatric Cohort. (PubMed, Influenza Other Respir Viruses) - "Although the current risk of infections with escape-mutants appears to be low, our results underline the need for continued surveillance, as resistance-conferring mutations to new mAbs circulated and may be selected under selection pressure."

Journal • Infectious Disease • Pediatrics • Respiratory Syncytial Virus Infections

Merck Receives Positive EU CHMP Opinion for ENFLONSIA (clesrovimab) for the Prevention of Respiratory Syncytial Virus (RSV) in Infants During Their First RSV Season (Businesswire) - "he CHMP recommendation will now be reviewed by the European Commission (EC) for marketing authorization in the European Union (EU), Iceland, Liechtenstein and Norway, and a final decision is expected before the end of the year....The CHMP recommendation is supported by results from the pivotal Phase 2b/3 CLEVER trial (MK-1654-004) (NCT04767373)....and the Phase 3 SMART trial (MK-1654-007) (NCT04938830)..."

CHMP • EMA approval • Respiratory Syncytial Virus Infections

Clesrovimab in Infants and Children at Increased Risk for Severe RSV Disease. (PubMed, N Engl J Med) - No abstract available

Journal • Respiratory Syncytial Virus Infections

Clesrovimab for Prevention of RSV Disease in Healthy Infants. (PubMed, N Engl J Med) - P2/3 | "In healthy preterm and full-term infants, a single dose of clesrovimab reduced the incidence of RSV-associated medically attended lower respiratory infection and RSV-associated hospitalization, with a safety profile similar to that of placebo. (Funded by Merck Sharp and Dohme; CLEVER ClinicalTrials.gov number, NCT04767373.)."

Journal • Infectious Disease • Respiratory Diseases • Respiratory Syncytial Virus Infections

Evaluating the potential clinical and economic impact of Clesrovimab for infants in England and Wales (V-Congress 2025) - No abstract available

Clinical • HEOR

Safety, efficacy, pharmacokinetics, and pharmacodynamics of clesrovimab in infants at increased risk of severe RSV disease: Subgroup analysis of Japanese participants in the phase 3 SMART trial (MK-1654-007) (V-Congress 2025) - No abstract available

Clinical • P3 data • PK/PD data • Respiratory Syncytial Virus Infections

Clesrovimab: First Approval. (PubMed, Drugs) - "Clesrovimab received its first US approval on 9 June 2025 for preventing RSV lower respiratory tract disease in neonates and infants born during, or entering, their first RSV season. This article summarises the milestones leading to this first approval."

Journal • Respiratory Diseases • Respiratory Syncytial Virus Infections

Cost-Effectiveness Analysis of Clesrovimab for Protection against Infant Respiratory Syncytial Virus Disease in the United States (IDWeek 2025) - No abstract available

Cost effectiveness • HEOR • Infectious Disease • Respiratory Syncytial Virus Infections

Clesrovimab Efficacy through 6 Months during a Time of Changing SARS-CoV-2 Nonpharmaceutical Interventions (NPIs): Subgroup Analysis of the China Cohort in the Phase 2b/3 CLEVER Trial (IDWeek 2025) - No abstract available

Clinical • P2/3 data • P2b data • Infectious Disease • Novel Coronavirus Disease

Respiratory Tract Infections and Co-Infections Following Administration of the Respiratory Syncytial Virus (RSV) Antibody Clesrovimab versus Placebo: Analysis of the Phase 2b/3 CLEVER Trial (IDWeek 2025) - No abstract available

Clinical • P2/3 data • P2b data • Infectious Disease • Respiratory Syncytial Virus Infections

Clesrovimab Efficacy through 6 Months during a Time of Changing SARS-CoV-2 Nonpharmaceutical Interventions (NPIs): Subgroup Analysis of the China Cohort in the Phase 2b/3 CLEVER Trial (IDWeek 2025) - No abstract available

Clinical • P2/3 data • P2b data • Infectious Disease • Novel Coronavirus Disease