Vaccine Info

Synagis (Palivizumab) RSV Monoclonal Antibody

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Last reviewed
November 8, 2023
Fact checked by
Robert Carlson, MD

Synagis® (Palivizumab) RSV Monoclonal Antibody

Synagis® (Palivizumab) is a respiratory syncytial virus (RSV) F protein inhibitor monoclonal antibody (mAb) indicated for the prevention of serious lower respiratory tract disease caused by RSV in pediatric patients. The mAb injection is given monthly throughout the RSV season. Synagis provides infants born prematurely (at or before 35 weeks and who are six months of age or less at th beginning of RSV season) the infection-fighting antibodies they lack, helping protect their vulnerable lungs from RSV from a passive immunization. Infants receive "ready-made" antibodies and do not have to produce them.

Synagis is not a vaccine but can help passively protect children with certain lung or heart conditions at high risk for severe RSV disease. For example, children with BPD/CLDP or HS-CHD are more likely to be hospitalized with an RSV infection than those without these conditions. However, children can still get severe RSV disease despite receiving Synagis. The safety and efficacy of SYNAGIS have not been established to treat RSV disease.

The American Academy of Pediatrics (AAP) strongly supported the consideration for using palivizumab in eligible patients during the interseasonal spread of RSV in late 2021. This AAP recommendation applied to regions experiencing high rates of RSV circulation in the spring and summer of 2021. Initiating palivizumab prophylaxis to eligible infants during a typical winter season is consistent with AAP policy

Synagis was approved for initial use in the U.S. by the FDA in 1998 and 2004 (BLA 103770/S-5059) and in Canada, Europe, the U.K., Israel, and India in 2023. On October 23, 2023, the U.S. CDC issued Health Alert Network Health Advisory (CDCHAN-00499) to provide options for clinicians to protect infants from RSV in the context of a limited supply of Beyfortus (nirsevimab) during the 2023-2024 RSV season in the U.S.

SYNAGIS® is a registered trademark of Arexis AB c/o Swedish Orphan Biovitrum AB. And SYNAGIS CONNECT® is a registered trademark of Arexis AB.

Synagis (Palivizumab) Cost Effectiveness

The Canadian health ministry published the results of a systematic review on February 1, 2023. It found that the cost-effectiveness results of PVZ as an RSV prophylaxis were heterogeneous across studies, ranging from dominant (i.e., less costly and more effective) to highly ineffective. 

Synagis (Palivizumab) Indication

Synagis is a mAb given as an injection monthly throughout the RSV season. Unlike a vaccine,  Palivizumab is an antibody that becomes effective within hours of injection. Synagis 50 mg and 100 mg for injection are recommended for high-risk babies most likely to be affected by severe RSV, including:

Preemies - Babies born 35 weeks or less and six months or younger at the beginning of RSV season. A 2013 clinical study published in the New England Journal of Medicine showed that SYNAGIS significantly reduced RSV-related hospitalizations in late-preterm infants 33-35 wGA6.

Lung Issues - Infants with a chronic lung condition known as BPD/CLDP (bronchopulmonary dysplasia/chronic lung disease of prematurity) require medical treatment within six months and 24 months of age or younger at the beginning of RSV season.

Heart Issues - Infants with a heart condition known as HS-CHD (hemodynamically significant congenital heart disease) and 24 months of age or younger at the beginning of RSV season.

Children should not receive SYNAGIS if they have had a severe allergic reaction. Signs and symptoms of a severe allergic reaction could include an itchy rash, swelling of the face, difficulty swallowing, difficulty breathing, bluish skin color, muscle weakness or floppiness, and/or unresponsiveness. 

Synagis (Palivizumab) Dosage

Single-dose liquid solution vials: 50 mg per 0.5 mL and 100 mg per 1 mL. per 15 mg per kg of body weight, administered intramuscularly before the RSV season, and the remaining doses administered monthly throughout the RSV season. Click Prescribing Information for SYNAGIS, including Patient Information.

Synagis (Palivizumab) Safety Information

SYNAGIS is contraindicated in children with a previous significant hypersensitivity reaction to SYNAGIS. Anaphylaxis and anaphylactic shock cases, including fatal cases, have been reported following initial exposure or re-exposure to SYNAGIS. 

Synagis (Palivizumab) News

September 30, 2023 - AstraZeneca India received approval from the Central Drugs Standard Control Organisation to import and sell Synagis (Palivizumab).

December 2022 - Harvard Pilgrim reminded providers of its policy regarding Synagis (palivizumab) for the 2022-2023 season. Synagis requires prior authorization and should be reserved for infants with a history of pre-term birth and children with chronic lung or congenital heart disease. For members who qualify to receive five doses, the first dose is typically administered at the beginning of November and the last dose at the beginning of March to protect into April.

April 3, 2022 - Israel's Health Ministry authorized the expanded vaccination of premature babies against RSV.

February 10, 2022 - Swedish Orphan Biovitrum AB announced its results for the fourth quarter and the entire year of 2021.

December 17, 2021 - The American Academy of Pediatrics updated palivizumab prophylaxis guidance to prevent severe RSV infection hospitalization during the 2021-2022 RSV season.

November 13, 2018 - AstraZeneca agreed to sell Synagis (palivizumab) U.S. rights to Swedish Orphan Biovitrum AB (Sobi).

October 1999 - Palivizumab is a new anti-RSV monoclonal antibody product indicated to prevent serious lower respiratory tract disease caused by RSV in pediatric patients at high risk of developing RSV disease.

Synagis (Palivizumab) Clinical Trials

Synagis (palivizumab) has been involved in over 20 clinical trials.

An observational study, Prospective, Non-interventional Observation Study for the Use of Palivizumab in High-risk Children in Germany- SYNAGIS, was carried out to gather comprehensive real-world data on the use of palivizumab in children at high risk for serious RSV disease.

This registry was designed as a post-marketing observational study and conducted to collect data on palivizumab administration, risk factors for complicated RSV disease, hospitalization frequency, and drug adherence.

Clinical Trials

No clinical trials found