Introduction

Respiratory Syncytial Virus (RSV) is one of the most common causes of lower respiratory tract infections in children at high risk of respiratory disease. It is associated with increased morbidity amongst preterm infants and babies born with chronic health conditions such as respiratory and/or cardiac complications.  

Nirsevimab is a long-acting monoclonal antibody given to infants for passive immunisation against RSV infection.  It has been shown to protect infants against hospitalisation for RSV-associated lower respiratory tract infection and against very severe RSV-associated lower respiratory tract infection.    

The Department of Health, Victoria funds Nirsevimab and administration for outpatients is coordinated by the Royal Children’s Hospital (RCH) Immunisation Service.  Nirsevimab is given as a single dose as the infant enters their first RSV season.  The RSV season generally begins 1st April each year and concludes at the end of September. 

Nirsevimab can be given from birth.  

Aim

The aims of this guideline are; 

• To ensure that the staff at RCH are providing safe and effective administration of Nirsevimab, according to the relevant legislation and The Royal Children’s Hospital Guidelines. 

• To ensure that parents receive consistent, accurate and reliable information about the procedure, including the potential risk and benefits, such as possible adverse events (AE), how common they are and how to report AE and get advice. 

• To streamline current practices to minimise excessive wait times and potential exposure to further pathogens for high-risk children. 

This guideline is restricted to use by Medical, Nursing and Pharmacy staff working at RCH. The guideline applies to neonate/infant inpatients or outpatients attending RCH and can be administered by Medical or Nursing staff with an order on EMR. 

Definition of Terms

• Adverse event – any negative reaction that follows immunisation.  It can be either expected or unexpected.  The immunisation may not actually trigger the Adverse Event, it may occur coincidentally. 

• Cold Chain – cold chain is process of transporting and storing vaccines within the temperature range of +2° - +8°. Maintenance of cold chain is essential for maintain vaccine potency and effectiveness. 

• Nirsevimab – human recombinant monoclonal antibody with activity against respiratory syncytial virus (RSV).  It is an RSV F protein-directed fusion inhibitor that is designed to bind to the fusion protein on the surface of the RSV virus i.e. binds to the site at which the virus would attach to a cell; effectively rendering it useless.      

• Passive Immunity – can occur naturally when maternal antibodies are transferred to fetus or can be artificially induced by the transfer of ready-made antibodies such as administration of blood products.

Assessment

Nirsevimab is recommended for: 

• Young infants born between 1 April – 30 September 2025 whose mothers did not receive RSV vaccine in pregnancy, or who were vaccinated less than 2 weeks before delivery.

• Infants born from 1 October 2024 – 31 March 2025, are eligible up to 8 months of age only.

• Young infants who are at increased risk* of severe RSV disease, regardless of their mother’s vaccination status.

• Children born on or after 1 October 2023 up to 24 months of age who have medical risk factors** for severe RSV disease in their 2nd RSV season. 
  

* The increased risk factors for severe RSV disease include:   

• Prematurity (infants born <32 weeks gestational age) 

• Infants with haemodynamically significant congenital heart disease 

• Significant immunosuppression e.g. such as from malignancy, solid organ transplant, haematopoietic stem cell transplant or primary immune deficiencies such as severe combined immunodeficiency (SCID) 

• Chronic lung disease that requires oxygen or respiratory support 

• Neurological conditions that impair respiratory function 

• Cystic fibrosis with severe lung disease or weight for length <10th percentile 

• Trisomy 21 or other genetic conditions that increase the risk of RSV 

**The medical factors for severe RSV disease in the 2nd RSV season 

• Aboriginal Torres Strait Islander infants

• Young children with conditions associated with increased risk of severe RSV disease (as above)

  
  

Notes: 

• Nirsevimab can be given from birth.  

• Nirsevimab can be given at the same time as routine vaccinations on the National Immunisation Program (NIP).  Different sites must be used. 

• If the patient tests positive for RSV infection, they can receive RSV specific monoclonal antibodies once recovered.

Contraindications: 

The only absolute contraindications to RSV monoclonal antibodies are: 

• Anaphylaxis after a previous dose of the same monoclonal antibody. 

• Anaphylaxis after any component^ of a monoclonal antibody.

  
  

^Components of the monoclonal antibody are: histidine, histidine hydrochloride, monohydrate, arginine hydrochloride, sucrose, polysorbate 80 and water. 

For more information please visit https://immunisationhandbook.health.gov.au/contents/vaccine-preventable-diseases/respiratory-syncytial-virus-rsv#rsvspecific-monoclonal-antibodies-infants-and-children-aged-24-months

Management

Dosage

For infants born during or entering their first RSV season the recommended dose of Nirsevimab is based on body weight (see table below) and is administered as a single intramuscular (IM) injection. 

• For children up to 24 months of chronological age who remain at increased risk for severe RSV disease in their second RSV season, the recommended dosage of Nirsevimab is a single 200 mg dose administered as two IM injections (2 x 100 mg) at different injection sites (preferably separate limbs) during the same visit.  

• For inpatients, Nirsevimab requires a medication order on the EMR.

• The child’s most recent weight must be recorded in EMR so that an accurate Nirsevimab dose can be confirmed. 

• For children undergoing cardiac surgery with cardiopulmonary bypass, an additional dose of Nirsevimab is recommended as soon as the child is stable after surgery to ensure adequate Nirsevimab serum levels.  

• First RSV season: 

  • If surgery is within 90 days after receiving Nirsevimab, the additional dose should be based on body weight at the time of the additional dose (see table above).  
  • If more than 90 days have elapsed since receiving Nirsevimab, the additional dose should be 50 mg regardless of body weight. 

• Second RSV season:

  • If surgery is within 90 days after receiving Nirsevimab, the additional dose should be 200 mg, regardless of body weight. 
    If more than 90 days have elapsed since receiving Nirsevimab, the additional dose should be 100 mg, regardless of body weight. 

Preparation

Nirsevimab for injection is available as: 

• 50mg pre-filled syringe (0.5mL), (concentration 100mg/mL) with a purple plunger rod 

• 100mg pre-filled syringe (1mL), (concentration 100mg/mL) with a light blue plunger rod 

Ensure the following steps are taken: 

• Ensure the Nirsevimab syringe is within expiry date and cold chain has been maintained.

• Remove the sticker with batch number details from the syringe (for documentation purposes – see below). 

• Perform hand hygiene. 

• Clean trolley or work surface with detergent and water or wipe.

• Identify and collect the appropriate injection equipment for the Nirsevimab to be administered.

• A 23g 25mm needle is to be used for the intramuscular injection.

• Perform hand hygiene.

• Holding the Luer lock in one hand (avoid holding the plunger rod or syringe body), unscrew the syringe cap by twisting it counter-clockwise with the other hand.  

• Attach a Luer lock needle to the prefilled syringe by gently twisting the needle clockwise onto the prefilled syringe until slight resistance is felt.  

• Hold the syringe body with one hand and carefully pull the needle cover straight off with the other hand. Do not hold the plunger rod while removing the needle cover or the rubber stopper may move. Do not touch the needle or let it touch any surface. Do not recap the needle or detach it from the syringe.  

• Prepare patient and safely position, including distraction techniques.

Administration

• Nirsevimab is given as an IM injection into the vastus lateralis muscle in the anterolateral aspect of the thigh.  Administer the entire contents of the prefilled syringe. 

• Dispose of the used syringe immediately.

• Refer to the intramuscular injection (IM) guideline to facilitate the administration of IM injections.

Procedural Pain Management

Injections can result in distress and anxiety for infants, children and their parents. It is important that effective pain management strategies are used during injection procedures. Some strategies that are recommended during administration of the Injection include: 

• Oral sucrose (infants) 

• Breastfeeding 

• Shaking a noisy toy 

• Topical anaesthetic agents, such as AnGel or EMLA cream (>1 month of age) can also be used. 
  

See also RCH clinical guideline document available at http://www.rch.org.au/rchcpg/hospital_clinical_guideline_index/Procedural_Pain_Management/ 

Post Vaccination

Immediate after care 

• Dispose of clinical and sharps waste  

• Cover the injection site with cotton wool and tape as needed 

• Gently apply pressure for 1-2 minutes (do not rub injection site, as it may lead to localised irritation) 

• As with any IM injection, caution should be used when administering Nirsevimab to patients with thrombocytopenia or anticoagulation.  Firm pressure should be applied for approximately 5-10 minutes. 

• After procedure perform hand hygiene 

• Inform parent to remain in the hospital with the child for at least 15 minutes after receiving the Nirsevimab (to observe for any immediate adverse event) 

Adverse Events  

• An adverse event is any untoward medical occurrence that follows medication administration and does not necessarily have a causal relationship with the usage of the Nirsevimab. 

• The most serious adverse event is anaphylaxis. Nursing staff must be aware of anaphylaxis management. See Anaphylaxis CPG for more information. 

• Any adverse event should be reported to the Immunisation service and can be contacted on 9345 6599. 

Nirsevimab Adverse reactions: 

• Uncommon (0.1% - <1%) 
• Fever, rash, injection site reaction 

Documentation requirements

• The Nirsevimab order will be documented in EMR.  
• After the dose has been given the order will need to be completed and signed off on EMR then recorded in the Infants Child Health record book.
• It will also need to be recorded on the Australian Immunisation Register (AIR).  Once signed off on the MAR, an inbasket message is sent to the Immunisation centre so that the dose can be recorded on AIR. 
• Details which should be recorded include:

  • Medication given (Including brand name, batch number, dose number) 

  • Date and time of injection 

  • Site of administration 

  • Name of the person who administered the injection. 

   

Please remember to read the disclaimer. 

The development of this nursing guideline was coordinated by Sonja Elia, Nurse Practitioner and Manager, Immunisation, and approved by the Nursing Clinical Effectiveness Committee. Updated March 2025.