Palivizumab (Synagis®) immunisation for Respiratory Syncytial Virus (RSV) infection
Palivizumab (Synagis®) is an injected passive immunisation or preventative agent which works against Respiratory Syncytial Virus (RSV) infection. It has been shown to lessen the risk of hospitalisation and intensive care for RSV-related respiratory illness.
Introduction
Palivizumab (Synagis®) is an injected passive immunisation or preventative agent which works against Respiratory Syncytial Virus (RSV) infection. It has been shown to lessen the risk of hospitalisation and intensive care for RSV-related respiratory illness. There are no available vaccines for children nor anti-viral treatment for RSV infection. Palivizumab is a monoclonal antibody and the only preventative medication currently approved and funded against RSV in New Zealand. An adult RSV vaccine for those aged > 60 years is licensed for private use in New Zealand (Arexvy).
For 2024-2025, high risk infants fulfilling the below criteria have funded access to monthly Palivizumab injections.
Eligibility criteria
(see link to special authority form)
Initial application from any relevant practitioner. Approvals valid for 6 months for applications meeting the following criteria:
| BOTH | 1 | Palivizumab to be administered during the annual RSV season; AND | ||||
| 2 | EITHER | |||||
| A. | BOTH | |||||
| I | Infant was born in the last 12 months; AND | |||||
| II | Infant was born at less than 32 weeks zero days' gestation; OR | |||||
| B | BOTH | |||||
| I | Child was born in the last 24 months; AND | |||||
| II | Any of the following: | |||||
| a | Child has severe lung, airway, neurological or neuromuscular disease that requires ongoing ventilatory/respiratory support (see Note 1 below) in the community; OR | |||||
| b | BOTH | |||||
| i | Child has haemodynamically significant heart disease; AND | |||||
| ii | Any of the following: | |||||
| Child has unoperated simple congenital heart disease with significant left to right shunt (see Note 2 below); OR | ||||||
| Child has unoperated or surgically palliated complex congenital heart disease; OR | ||||||
| Child has severe pulmonary hypertension (see Note 3 below); OR | ||||||
| Child has moderate or severe left ventricular (LV) failure (see Note 4 below); OR | ||||||
| c | Child has severe combined immune deficiency, confirmed by an immunologist, but has not received a stem cell transplant; OR | |||||
| d | Child has inborn errors of immunity (see Note 5) that increase susceptibility to life-threatening viral respiratory infections, confirmed by an immunologist. | |||||
Notes:
Ventilatory/respiratory support includes those on home oxygen, CPAP/VPAP and those with tracheostomies in situ managed at home
Child requires/will require heart failure medication, and/or child has significant pulmonary hypertension, and/or infant will require surgical palliation/definitive repair within the next 3 months
Mean pulmonary artery pressure more than 25 mmHg
LV Ejection Fraction less than 40%
Inborn errors of immunity include, but are not limited to, IFNAR deficiencies
Dosage and administration
Palivizumab (Synagis®) is administered by healthcare professionals as an intramuscular injection. It can be given from birth as it is used to prevent hospitalisation and is generally used on discharge and outpatient use. However it may be given within the week of planned discharge from NICU or in long stay inpatients at risk of RSV exposure.
What is the dose?
The dose is 15 mg per kg given every 4 weeks by intramuscular injection for the expected duration of the ‘RSV’ season which typically spans 6 months between May/June to September/October, peaking in July (Southern hemisphere). Therefore first dose should start prior to RSV season. Ideally the interval between the first and second dose should be no greater than 28 days and subsequent doses between 28-35 days apart.
The vials are 1 mL concentration containing 100 mg/mL and dose can be rounded up to the nearest whole number. For example, a 3.5 kg infant would be given 53 mg (0.53mL) intramuscularly into the anterolateral thigh. Dose adjustments are needed based on monthly weight gain of the infant. Volumes of more than 1 mL are usually given as a divided dose.
Intramuscular injection in the anterolateral thigh -see FAQs below and the RCHMelbourne Guideline on Palivizumab (Synagis®) administration for Health Professionals.
The manufacturer advises that Palivizumab (Synagis®) is for single use only and the product does not contain a preservative. However, once accessed, multidose use of single-use vials of palivizumab should be used ideally by 2 hours (and safely up to 6 hours).
Where possible, appointments can be planned to facilitate vial sharing and reduce cost. If the contents of the vial are to be shared between two patients, ensure there is a clear plan in place, aiming to minimise the gap between administering to each patient and use strict aseptic technique.
What are the side effects or adverse events?
| Common (>1%) | Injection site reaction Very common (>10%) adverse events reported with SYNAGIC (Palivizumab) also included upper respiratory symptoms, rhinitis, fever, rash, cough, diarrhoea and wheeze although these occurred at the same rate amongst placebo recipients) |
|---|---|
| Infrequent (0.01 - 1%) | Anaemia, elevated liver enzymes |
| Rare (<0.1%) | Hypersensitivity (including anaphylaxis) |
Frequently asked questions
What is Palivizumab?
This is a humanized monoclonal antibody (IgG) directed against the antigens of the Respiratory Syncytial Virus and used to prevent RSV. It does not treat RSV once the infection has been acquired.
How is Palivizumab given?
Into the muscle of the anterolateral thigh or vastus lateralis (see Immunisation Handbook 'processes for safe immunisation')
How is Palivizumab stored and can it be given in the home?
The first injection likely for most infants will be given at hospital as part of discharge planning for example at the neonatal unit. Doses after that will be given at a healthcare premise, such as an outpatients or through homecare services with appropriate cold chain, transportation, storage and administration protocols.
Can infants who receive Palivizumab receive routine immunisations?
Yes, all the usual immunisations including live vaccinations such as oral rotavirus vaccine (or BCG if indicated) can still be given at the usual times and/or concurrently with Palivizumab.
Are there any medicines which interact with Palivizumab or impact on diagnostic testing for RSV?
Palivizumab does not have significant interactions with any other medications nor monoclonal antibodies. It does not interact with the commonly used RSV diagnostic test (PCR testing on nasopharyngeal aspirate).
What if my infant acquires RSV or has had RSV this winter?
Although the protection against RSV is not long lasting (over years), it is likely that short term protection happens after one episode of RSV. If a baby has had a positive test for RSV infection, then delay Palivizumab for 3 months and recommence if still required to cover the end of the RSV season. This 3 month gap can be shortened in immunocompromised patients.
What if corrective cardiac surgery is done during the RSV season?
Decision to continue is based on infant remaining at high risk of RSV complications and most likely would continue. However Palivizumab can be ceased without completing the 6 injections over RSV season if this is determined by medical team.
Do side effects become worse with subsequent dosing?
From routine post-marketing reports, adverse events observed in patients following a sixth or greater dose were similar in character and frequency to those after the initial five doses.