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RSV Overview

Respiratory syncytial virus (RSV) is an enveloped, single-stranded RNA virus belonging to the family of paramyxoviridae and a human pathogen in the genus Pneumovirus.1

Most RSV infections cause mild to moderate upper respiratory illness and cold-like symptoms. However, in certain high-risk pediatric patients, RSV may cause serious lower respiratory tract disease.

Electron Photomicrograph Locating RSV Proteins
  • The virus can survive on fomites for 6 to 7 hours but does not survive well at temperatures ≥37°C2
  • RSV is destroyed by slow freezing and thawing1
  • The infectivity of RSV is determined by 2 surface glycoproteins, F and G3
  • The F and G surface glycoproteins have also been identified as targets of anti-RSV antibodies, but only the F protein remains highly conserved across both major strains of RSV3
  • The F protein, therefore, was determined to be the appropriate target of an anti-RSV monoclonal antibody3

About the photograph: Electron photomicrograph of budding virion (129) used to indicate location and chain length of the RSV proteins. (Peter Collins, 1989; Fields Virology, 2nd ed, 1990).

RSV Transmission

RSV is still transmitted in hospitals

In the absence of adequate infection-control practices, RSV can spread very rapidly in the hospital environment and other settings. RSV transmission can occur by contact with large droplet aerosols or fomites and by contact with infectious secretions through hand contamination and self-inoculation of the eyes, nose, and mouth.


You can help prevent the spread of RSV

RSV transmission may be prevented by frequent hand washing by parents and healthcare providers, isolating infants 
from people with upper respiratory infections, and avoiding crowds during the RSV season.4

RSV Seasonality

Virology analysis plays a critical role in preventing RSV-related hospitalizations5

RSV Season

The start and end of RSV season can vary year to year, state to state, and can even vary within communities in the same region.6,7 Throughout much of the US, the RSV season begins in the fall and runs into spring—although year-round RSV activity has been reported in Florida and Puerto Rico.6-10 Local historical data can help determine the start and end of RSV season in a geographic region.5,6

Before determining the start and end of RSV season, it's important to consider different sources of surveillance data, such as:

  • Historical trends that can help estimate the start and duration of RSV season5,6
  • The level of RSV activity still in the community5
  • RSV-related hospitalizations5

National and regional RSV season onset and offset is defined by the National Respiratory and Enteric Virus Surveillance System (NREVSS)6,11

In NREVSS, the onset week in an area (national, region, or state) is defined as the first of 2 consecutive weeks when the weekly percentage of all specimens testing positive for RSV antigen in all reporting laboratories in the area is ≥10%. The offset is the end of the last 2 consecutive weeks when the weekly percentage positive exceeds 10%. Visit CDC NREVSS for reports to stay updated on RSV activity in your region.

Despite the seasonality of RSV activity, severe RSV disease is the #1 reason infants under 1 year of age are 
hospitalized in the US12

Ask your MedImmune representative
about obtaining RSVAlert® reports

Visit RSVAlert >

Important Safety Information

Synagis is indicated for the prevention of serious lower respiratory tract disease caused by respiratory syncytial virus (RSV) in children at high risk of RSV disease. Safety and efficacy were established in children with bronchopulmonary dysplasia (BPD), infants with a history of premature birth (≤35 weeks gestational age), and children with hemodynamically significant congenital heart disease (CHD). The recommended dose of Synagis is 15 mg/kg of body weight given monthly by intramuscular injection. The first dose of Synagis should be administered prior to commencement of the RSV season and the remaining doses should be administered monthly throughout the RSV season. Children who develop an RSV infection should continue to receive monthly doses throughout the RSV season.

The efficacy of Synagis at doses less than 15 mg/kg, or of dosing less frequently than monthly throughout the RSV season, has not been established.

Synagis is contraindicated in children who have had a previous significant hypersensitivity reaction to Synagis. Cases of anaphylaxis and anaphylactic shock, including fatal cases, have been reported following initial exposure or re-exposure to Synagis. Other acute hypersensitivity reactions, which may be severe, have also been reported on initial exposure or re-exposure to Synagis. The relationship between these reactions and the development of antibodies to Synagis is unknown. If a significant hypersensitivity reaction occurs with Synagis, its use should be permanently discontinued. If a mild hypersensitivity reaction occurs, clinical judgment should be used regarding cautious readministration of Synagis. As with any intramuscular injection, Synagis should be given with caution to children with thrombocytopenia or any coagulation disorder. Palivizumab may interfere with immunological-based RSV diagnostic tests, such as some antigen detection-based assays.

Adverse reactions occurring greater than or equal to 10% and at least 1% more frequently than placebo are fever and rash. In post-marketing reports, cases of severe thrombocytopenia (platelet count <50,000/microliter) and injection site reactions have been reported.

Please see full Prescribing Information for Synagis, including Patient Information.