Respiratory syncytial virus (RSV) is the most common cold virus in children. Almost all children get an RSV infection in their first year of life. The virus is mainly seen in winter. 

What is an RSV infection?

An RSV infection is an infection of the airways caused by respiratory syncytial virus. The virus mainly causes serious illness in young babies, leading to shortness of breath caused by an infection of the small airways (bronchiolitis), or possibly even pneumonia. Premature babies, children with a congenital heart abnormality, and children with Down’s syndrome have a higher risk of a more severe course of illness. Children in the Netherlands hardly ever die from RSV.

Among older people who are in poor health, RSV is a common cause of respiratory infections. There are sometimes RSV outbreaks in residential care facilities and nursing homes.

There are two types of RSV:RSV-A and RSV-B. These types can occur simultaneously among the population and cause exactly the same symptoms. RSV can cause some long-term effects, such as wheezing and asthma.

What are symptoms of RSV infection?

The time between exposure and the first symptoms of illness caused by RSV ranges from 2 to 8 days. The most common symptoms are a nasal cold and coughing. If a child has an initial infection as an infant or toddler, the course of illness can be severe and accompanied by fever, shortness of breath due to inflammation and congestion of the small airways (bronchiolitis), or pneumonia. RSV infection can also cause ear infections in children.

In subsequent infections, the symptoms are usually mild, but flu-like symptoms may also occur. Among older people who are in poor health and people with underlying heart or lung conditions, there is an increased risk of complications such as pneumonia.

In most cases, RSV infection does not require any treatment. The symptoms generally disappear on their own after a few days to a week. It is advisable to consult the GP if one or more of the following applies:

  • Severe shortness of breath;
  • High fever (above 39 degrees);
  • Fever for more than 3 days;
  • A young baby under 3 months has a fever;
  • Children under 1 year old are not drinking or eating properly.

RSV transmission and prevention

How does RSV spread?

RSV is present in the nose and throat of people who are infected, and can be transmitted by droplets released during coughing, sneezing and talking. The virus enters the body via the nose, eyes or mouth. A person with RSV can infect others before showing any symptoms of illness. Once a person with RSV is fully recovered, they are no longer contagious. Children under 2 years old are contagious for longer: about three to four weeks after the onset of the infection.

How to prevent RSV?

Children who are born too early (premature babies) and babies with severe heart disease can be protected against RSV in their first year of life by passive vaccination with antibodies. No vaccine is currently available for active vaccination against RSV. Many RSV vaccines are currently being developed and will hopefully reach the market in a few years. Breastfeeding also helps protect against RSV infections in babies.

How common are RSV infections?

RSV is common in the Netherlands, especially in winter (November to March). Almost all children under the age of two come into contact with the virus. In the Netherlands, about 100 out of 1000 babies who are ill (=10%) visit their GP because of RSV infection. 10 of these babies (10%) are hospitalised. One baby out of those admitted to hospital (10%) ends up in intensive care (ICU).

Among older people in residential care facilities and nursing homes, RSV infection ranks second in common causes of outbreaks of infectious disease worldwide. In the Netherlands, it is estimated that even more older people die from RSV than from flu (influenza) in some seasons.

More frequently asked questions about RSV

Research on RSV infection

RIVM is working with the Netherlands Institute for Health Services Research (Nivel) to monitor how many people go to their GP for respiratory symptoms. Samples are taken from the throat and nose of some of these patients to test what is causing their symptoms. Among other things, the samples are tested for flu (influenza) and for RSV. This helps RIVM gain insight into the number of cases involving RSV among people who visit their GP with respiratory symptoms. 

Besides surveillance, RIVM is also researching RSV through laboratory research (virology and immunology) and population screening (epidemiology).

RIVM is a partner in the project. Among other things, this project aims to gain a better understanding of RSV disease burden, for example by identifying high-risk groups and improving RSV surveillance. In addition, laboratory methods are being developed to show whether someone has been exposed to RSV (not recently, but in the past). Eventually, this could be used to monitor vaccine effectiveness. RESCEU is a European project that received funding from the Innovative Medicines Initiative 2 Joint Undertaking (IMI2) under grant agreement Nº 116019.  IMI2 receives support from the European Union’s Horizon 2020 research and innovation programme and the European Federation of Pharmaceutical Industries and Associations.

RIVM is also investigating natural immunity against RSV infection. The goal is to find out how a person can be protected against this virus. This information will be important for advising on the introduction of new vaccines in the future. For example, RIVM is investigating how the antibodies that babies get from their mothers during pregnancy can help protect them. RIVM is also investigating how RSV is able to influence the natural immune response. This research is funded in part by the Netherlands Organisation for Health Research and Development (ZonMw).