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 only partial and temporary immunity, reinfection with RSV can occur in all ages. Repeat infections are often less severe.

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

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 year 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.

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 contact with contaminated surfaces. A person is infectious for 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 late fall and lasts until spring. Most cases occur 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 tested with a nasopharyngeal swab for RSV RT-PCR.


Most healthy children and adults will recover on their own in 1 to 2 weeks. Most treatment for RSV is to address symptoms and provide supportive care.

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

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

Prevention and control

The most effective ways to prevent RSV transmission is to:

There are some products that have been shown to prevent RSV disease.

For infants, there are 2 medications (monoclonal antibodies) that are approved for use to prevent RSV disease.

  1. Palivizumab/Synagis (AstraZeneca) has been available in Canada for decades and is given monthly to prevent disease.
  2. Nirsevimab/Beyfortus (Sanofi) is a newly authorized product and 1 dose may protect infants for up to 6 months.

These products cannot be used to treat infants who already have RSV disease.

For older adults, Arexvy (GSK) is a newly authorized vaccine to prevent RSV disease for those 60 years and older.

Consult the following resources for more information:


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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