Respiratory syncytial virus (RSV): For health professionals

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What health professionals need to know about RSV

RSV is an enveloped RNA virus. It causes annual epidemics of respiratory illness in countries around the world. In Canada, elevated RSV activity generally takes place from late fall to early spring.

RSV is a common childhood illness and the most common cause of lower respiratory tract illness in young children everywhere. Most children will experience RSV infections by the age of 2.

Since infection produces partial and temporary immunity, reinfection with RSV can occur in all ages. Repeat infections are usually less severe.

Primary infection with RSV generally presents as lower respiratory tract disease, pneumonia, bronchiolitis, tracheobronchitis or upper respiratory tract illness.

The risk of severe outcomes from RSV infection is higher among:

In severe cases, RSV requires hospitalization and may be life-threatening. Hospitalization rates are highest among children under 1 years old, and especially within the first 2 months of life.

Clinical symptoms

The incubation period of RSV ranges from 2 to 8 days. Common clinical presentations can include:

In infants, the only symptoms of RSV may be decreased activity, difficulty breathing, difficulty feeding and/or irritability.

RSV infection can lead to lower respiratory tract infections, such as bronchiolitis and pneumonia. Severe infection from RSV is more common among infants and young children, immunocompromised individuals and older adults with certain underlying conditions.


Humans are the only source of infection. RSV transmission occurs from respiratory particles containing the virus and from direct contact with contaminated surfaces. The infectious period is about 8 days on average, with a range of 1 to 21 days. The incubation period is sometimes longer in some infants and people with weakened immune systems.

RSV causes annual seasonal epidemics. In Canada, the RSV season typically begins in October or November and lasts until April or May. Most cases occur in December through March.


In most cases, the diagnosis is clinical, and specific laboratory testing is not done for outpatients. Often a person admitted to hospital is given a nasopharyngeal swab for RSV RT-PCR.

The National Microbiology Lab provides reference diagnostic testing for RSV and RSV sub-typing by RT-PCR. A nasopharyngeal swab is the preferred specimen type.


Most healthy children and adults will recover on their own in 1 to 2 weeks. There is no specific treatment for RSV.

Over-the-counter medications, such as acetaminophen or ibuprofen, can be given to relieve the symptoms associated with RSV, such as fever and pain. Drinking plenty of fluids and getting adequate rest is strongly encouraged.

People with severe RSV may need to be admitted to the hospital for additional oxygen and supportive care.

Learn more about:

Prevention and control

Currently, there is no vaccine available to prevent RSV, though several are under development.

Passive immunization with palivizumab is available as a prophylaxis against severe RSV disease for high-risk infants and children. This monoclonal antibody preparation provides temporary passive protection and is injected into the muscle. Although the risk of severe RSV disease is reduced, palivizumab does not completely prevent RSV infection.

Consult the National Advisory Committee on Immunization's guidance on the recommended use of palivizumab to reduce complications of RSV infection in infants

The most effective ways to prevent RSV transmission is to:

Learn more about the 2022 to 2023 respiratory illness season and measures to take given the co-circulation of RSV, COVID-19 and influenza:


Canada participates in national and international activities to detect and monitor the spread of RSV. The Public Health Agency of Canada maintains the Respiratory Virus Detection Surveillance System. This national surveillance system monitors the circulation of seasonal respiratory viruses, including RSV every week, year-round.

Find up-to-date information on respiratory virus activity in Canada:

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