[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Immunoglobulins and antitoxins](https://durgical.com/en/pharmacology/classes/immunoglobulins-and-antitoxins/) › Nirsevimab # Nirsevimab ## Immunoglobulins and antitoxins? Immunoglobulins and antitoxins Long-acting antibody injected once into infants to protect them through the RSV season; it gives ready-made immunity and is not a vaccine. Updated Nov 12, 2026 Also called: nirsevimab-alip ## Quick facts **Group** [Immunoglobulins and antitoxins](https://durgical.com/en/pharmacology/classes/immunoglobulins-and-antitoxins/) **Target** Fusion (F) protein of respiratory syncytial virus **Key effects** Pain · Rash **Monitor** Signs of bleeding at the site **ATC** J06BD08 No doses: the clinician sets them by the current guideline. On this page - The basics Mechanism of action - Indications - Adverse effects - Pharmacokinetics - Memory aid - Safety Contraindications - Key interactions - What is monitored - Administration and safety - Pregnancy and breastfeeding - Nursing care - Study Test yourself - Connections Connections ## Mechanism of action ◆**Fusion (F) protein of respiratory syncytial virus**Nirsevimab ⓘ The figure shows the RSV F protein bound to MEDI8897, the research name of nirsevimab. **Target in 3D:** Fusion (F) protein of respiratory syncytial virus. PDB structure 5UDC (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/5UDC) · Drag to rotate · pinch to zoom Nirsevimab is a human monoclonal antibody against the F protein that RSV uses to fuse with the cells of the airway. By binding F it stops the virus from entering and infecting cells. It was engineered to be long-acting, so one injection covers a typical RSV season. Protection is passive: the antibody itself protects, and the infant's immune system is not activated or trained. - Binds the F (fusion) protein on the surface of RSV - F can no longer fuse the virus with airway cells - Infection and spread to the lower airways are blocked - Long-acting design keeps it protective through the season ## Indications - Prevention of severe RSV lower respiratory tract disease in infants born during or entering their first RSV season [Bronchiolitis (RSV) →](https://durgical.com/en/conditions/bronchiolitis/) - Children up to their second season who remain at increased risk (for example chronic lung disease or severe immunocompromise) [Bronchiolitis (RSV) →](https://durgical.com/en/conditions/bronchiolitis/) ## Adverse effects ### Common - Pain, swelling or hardness at the injection site - Rash, uncommon ### Serious (rare, important) - Hypersensitivity reactions, including anaphylaxis, uncommon ## Contraindications - History of a severe allergic reaction (anaphylaxis) to nirsevimab or any component ## Key interactions **Routine childhood vaccines, including live vaccines** Can be given at the same visit, at a different site; no interval is needed. **Maternal RSV vaccine during pregnancy** Most infants need one or the other, not both; if the mother was vaccinated well before birth the antibody is usually not needed. ## What is monitored - Observation after the injection for allergic reactions - Signs of bleeding at the site in infants with low platelets or clotting disorders ## Administration and safety - Single intramuscular injection by a trained health worker - Ideally given in the birth hospitalisation or the first week of life for infants born in the season, or just before the season starts - Usually deferred in a moderate or severe acute illness - It is an antibody, not a vaccine: the record states the product given ## Pregnancy and breastfeeding Not given in pregnancy: it is given to the infant. The alternative strategy is RSV vaccination of the mother during pregnancy. ## Nursing care - Ask whether the mother received an RSV vaccine in pregnancy and when - Ask about bleeding disorders, low platelets or anticoagulants - Explain to parents that it gives ready-made protection and does not prevent all colds - Teach signs that need urgent care: breathing difficulty, bluish lips, poor feeding ## Pharmacokinetics **Absorption** Given by intramuscular injection. **Half-life** Long-acting by design: one dose protects through a typical RSV season. ## Memory aid «Nirsevimab = RSV shield on loan»: a borrowed antibody (-mab) that blocks the F protein for one season; it protects but does not train the immune system. ## Test yourself Think of the answer, then tap the question to see it. ## Which RSV protein does nirsevimab target? The fusion (F) protein in its prefusion form, which the virus needs to enter airway cells. ## Is nirsevimab a vaccine? No. It is a monoclonal antibody that gives passive, ready-made protection without training the infant's immune system. ## How many injections of nirsevimab are usually needed for one RSV season? Usually one: it is a long-acting antibody designed to protect through a typical season. ## Does an infant usually need nirsevimab if the mother received the RSV vaccine well before birth? Usually not: most infants need either the maternal vaccine or the infant antibody, not both. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/nirsevimab/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## Connections ## Related drugs 3 - [Normal human immunoglobulin (IVIG)](https://durgical.com/en/pharmacology/normal-human-immunoglobulin/) - [Respiratory syncytial virus (RSV) vaccine](https://durgical.com/en/pharmacology/respiratory-syncytial-virus-vaccine/) - [Rabies immunoglobulin](https://durgical.com/en/pharmacology/rabies-immunoglobulin/) ## Related conditions 1 - [Bronchiolitis (RSV)](https://durgical.com/en/conditions/bronchiolitis/) [← Back to the class: Immunoglobulins and antitoxins](https://durgical.com/en/pharmacology/classes/immunoglobulins-and-antitoxins/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [RSV Immunization Guidance for Infants and Young Children](https://www.cdc.gov/rsv/hcp/vaccine-clinical-guidance/infants-young-children.html) (Centers for Disease Control and Prevention (CDC), 2026); [Nirsevimab-alip: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a623033.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [Crystal Structure of RSV F A2 Bound to MEDI8897](https://www.rcsb.org/structure/5UDC) (RCSB Protein Data Bank, 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=J06BD08) (WHO Collaborating Centre for Drug Statistics Methodology, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/nirsevimab/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/nirsevimab/