Is Respiratory Syncytial Virus (RSV) Contagious?

Respiratory syncytial virus (RSV) infection causes inflamed airways in the lungs.

Respiratory syncytial virus (RSV) is contagious. In the United States, it's the most common cause of inflammation of the small airways in the lungs (bronchiolitis) and of pneumonia in children under 1 year of age. It also is significant cause of respiratory illnesses in older adults. Nearly all children in the U.S. will have been infected by RSV by 2 years of age. RSV usually causes a mild respiratory infection, but it can occasionally cause more serious infections that require hospitalization from breathing compromise with bronchiolitis or pneumonia. RSV was discovered in 1956 (isolated from a chimpanzee but later found to be from human origins) and was designated chimpanzee coryza agent by J. Morris and associates. Years later, the viruses were renamed respiratory syncytial virus (RSV). In virology terminology, RSV is an enveloped RNA virus and is a member of the family Paramyxoviridae that infects lung tissue.

Most infants and children and older adults usually develop symptoms about 4-6 days after their first exposure to RSV. This is referred to as the incubation period. Symptoms of RSV include a runny nose and decreased appetite followed by coughing, sneezing, no fever, or a mild fever at 1-3 days. Most individuals with RSV who are otherwise healthy do not require hospitalization. However, some very young infants and others may develop more serious symptoms of wheezing, irritability, decreased activity, cyanosis (blue-gray colored skin), and breathing difficulties. Some of these individuals may require short (3-5 days) hospital stays. Even more severe infections can require supported breathing. Definitive diagnosis can be done by viral cultures, detecting RSV antigens, PCR assays, and molecular probes (molecules used to detect other molecules or structures).

The symptoms described in the previous section usually last approximately 1 week during which symptoms gradually disappear. Individuals are usually no longer contagious after the symptoms disappear (5-8 days). However, individuals with weakened immune systems can be contagious for as long as 4 weeks.

RSV is spread person to person. Coughs and/or sneezes distribute droplets filled with the RSV microbes into the air. If uninfected individuals have the droplets contact their mouth, nose, or eyes, or inhale them, they may become infected with RSV. Infections can also occur from direct person-to-person contact such as kissing the face of an infected child. In this way, RSV can be transferred from infants to adults and from infants to pregnant adults. In addition, indirect contact with RSV-infected droplets that have landed on surfaces that can be touched, such as doorknobs, eating utensils, or toys, can also become sources that transfer the infection. RSV can survive for many hours on hard surfaces.

Most children and some adults who develop RSV infections do not need to seek medical care. Individuals with premature infants, young children with chronic heart or lung conditions, and children or adults with weakened immune systems should seek medical care immediately if infection with RSV is suspected. While there is no commercially available RSV vaccine, there is a drug called palivizumab (Synagis) that may be used in certain infants and children who are at high risk for developing severe RSV infection. Unfortunately, this drug cannot help or cure children already suffering from serious RSV disease and cannot prevent infection with RSV. The drug's function, according to the American Academy of Pediatrics, is to reduce the severity of RSV in children (mainly under 1 year of age) with underlying problems such as congenital heart disease, chronic lung disease, or other debilitating conditions.