What causes RSV

Respiratory syncytial virus (RSV)

Pathogen and transmission

RSV is an abbreviation for the human respiratory syncytial virus. The virus is responsible for most cases of acute bronchitis in infants and young children. RSV causes annual epidemics in fall and winter. In Switzerland, a stronger epidemic occurs every two years.

The transmission from person to person occurs through droplet infection with close contact, with the conjunctiva and nasal mucous membrane forming the entry portals. Transmission is also possible through contaminated objects and surfaces (including hands).

The contagion usually lasts for 1 to 5 days. It peaks during the first few days of the disease.

Clinical picture

The incubation period from infection to disease lasts 2 to 8 days.

Then symptoms such as runny nose, severe cough, fever and often conjunctivitis appear. A bacterial otitis media often occurs as an additional infection. The most common complications are pneumonia, which occurs in up to 40% of hospitalized cases, especially in infants and children under two years of age. In older children, adolescents, and adults, RSV can occasionally cause a prolonged, dry cough. As a rule, older children, adolescents and adults are only affected by mild symptoms of the disease, but they can infect infants and toddlers.

Distribution and frequency

RSV is common worldwide. RSV infection is by far the most common lower respiratory tract infection in infants and leads to hospitalization in 1 to 2% of small children due to shortness of breath and insufficient food and fluid intake. In Switzerland this corresponds to around 1,000 hospital admissions annually.


There is no vaccination and therapy can only relieve symptoms. RSV infection does not leave permanent immunity and therefore the virus can successfully re-infect people of all ages. The only protection is therefore to keep babies and young children away from people who are coughing and feverish.