What is Respiratory Syncytial Virus (RSV)?

Respiratory Syncytial Virus (RSV) is a highly contagious virus with symptoms of illness that include decreased appetite, coughing, sneezing, runny nose, wheezing, and fever that generally occur within four to six days after infection. Newborns and young infants may present only with symptoms of breathing problems, irritability, and decreased appetite. Infants and young children, as well as older adults, are considered most susceptible to RSV infection.¹

RSV is an enveloped virus belonging to the genus Pneumovirus, family Paramyxoviridae. It contains 11 proteins that are encoded by the non-segmented RSV genome. As a result of being non-segmented, the virus is unable to shift antigenically to cause significant pandemics. While new genotypes of RSV can occur, the older types do not disappear, allowing for both old and new types to circulate simultaneously for long periods of time.²

There are two different subgroups of RSV, A and B, with subgroup A thought to be slightly more virulent than B. The two groups are defined by the reaction of the major surface proteins, with the G protein of the virus helping to attach to the cells of the airway and the F protein assisting by entering the cells of the infected individual.³ Both RSV A and B can circulate at the same time, however, one subgroup usually predominates.⁴

Most RSV infections resolve within one to two weeks without treatment, although complications such as pneumonia or bronchiolitis can occur, resulting in hospitalization. By two years of age, most infants and children will have had RSV,⁵ however, it is possible to have more than one infection throughout a lifetime.⁶ Most adults who become infected will have symptoms of respiratory illness that include cold-like symptoms such as cough, runny nose, sore throat, fever, and general discomfort.⁷

RSV generally begins to circulate in the fall and peaks during the winter months in the U.S. and countries with similar climates; however, seasonality can change in communities from year to year.⁸

IMPORTANT NOTE: NVIC encourages you to become fully informed about Respiratory Syncytial Virus (RSV) and the Respiratory Syncytial Virus (RSV) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

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