Palivizumab, sold under the brand name Synagis, is a monoclonal antibody produced by recombinant DNA technology used to prevent severe disease caused by respiratory syncytial virus (RSV) infections.

[2][4] It is recommended for infants at high-risk for RSV due to conditions such as prematurity or other medical problems including heart or lung diseases.

In two phase III clinical trials in the pediatric population, palivizumab reduced the risk of hospitalization due to RSV infection by 55% and 45%.

[5] Palivizumab is dosed once a month via intramuscular (IM) injection, to be administered throughout the duration of the RSV season, which in based on past trends has started in Mid-September to Mid-November.

Infants younger than one year with bronchopulmonary dysplasia (i.e. who were born at <32 weeks gestation and required supplemental oxygen for the first 28 days after birth) and infants younger than two years with bronchopulmonary dysplasia who require medical therapy (e.g. supplemental oxygen, glucocorticoids, diuretics) within six months of the anticipated RSV season are recommended to use palivizumab as prophylaxis.

[13] It is not clear if palivizumab is effective and safe for the other medical conditions that put them at a higher risk for serious cases of RSV such as deficiencies in their immune system.

[11] A 2019 (updated in 2023) Cochrane review found no differences in palivizumab and placebo on outcomes of mortality, length of hospital stay, and adverse events in infants and children aged up to 3 years old with RSV.

The half-life of this drug is approximately 20 days with three doses sustaining body concentrations that will last the entire RSV season (5 to 6 months).

A 2008 meta-analysis estimated clearance in the pediatric population by considering maturation of CL and body weight which showed a significant reduction compared to adults.

[26][21][27] A 2013 meta-analysis reported that palivizumab prophylaxis was a dominant strategy with an incremental cost-effectiveness ratio of $2,526,203 per quality-adjusted life-year (QALY).

The immunized children who were exposed to the virus in the community developed an enhanced form of RSV disease presented by wheezing, fever, and bronchopneumonia.

[30] Subsequent attempts to develop an attenuated live virus vaccine with optimal immune response and minimal reactogenicity have been unsuccessful.

[32] In 1995, the U.S. Food and Drug Administration (FDA) approved the use of RespiGam (RSV-IGIV) for the prevention of serious lower respiratory tract infection caused by RSV in children younger than 24 months of age with bronchopulmonary dysplasia or a history of premature birth.