Respiratory Synctial Virus (RSV) Vaccine

Respiratory syncytial virus, usually shortened to RSV, is a common virus that infects the nose, throat and lungs. In most healthy adults it feels like a heavy cold, but in older adults, in people with heart or lung conditions and in babies it can move down into the lower airways and cause bronchiolitis or pneumonia. Almost everyone catches RSV by the age of two, and people are reinfected throughout life.

What RSV is, and what it is not

RSV is not a childhood illness that adults have outgrown. Immunity after infection is short-lived, so reinfection is normal at every age, and the consequences get more serious as people get older or live with other conditions. RSV circulates in Canada mainly from late autumn through early spring, overlapping with influenza and COVID-19.

It is also not something you can identify by how it feels. RSV, influenza and common cold viruses cause overlapping symptoms, and no one can tell them apart by symptoms alone. A laboratory swab is the only way to know which virus is involved. What distinguishes RSV in practice is that it is more likely than a common cold to reach the lower airways in older adults and infants, which is why new wheeze or breathlessness matters more than the label on the illness.

Signs and symptoms

• Runny or blocked nose, and sneezing
• Cough, which can become persistent
• Sore throat and hoarseness
• Fever, usually mild in adults
• Wheezing or noisy breathing
• Shortness of breath, or a flare-up of existing asthma or COPD
• In infants: irritability, poor feeding, and pauses in breathing

The same virus can produce a mild cold in one member of a household and a hospital admission in another, and the difference is usually age and underlying health rather than anything about the exposure.

What raises the risk

Some things cannot be changed:

• Being aged 60 and older, with risk climbing steeply after 75
• Living with COPD, asthma, heart disease, diabetes or kidney disease
• Having a weakened immune system from illness or medical treatment
• Being an infant, particularly under 6 months or born prematurely

Others can often be worked on, usually with support from a health care team:

• Living in a nursing home or other chronic care facility, where outbreaks spread quickly
• Close indoor contact during RSV season, and shared care settings
• Tobacco smoke exposure in the household

How RSV is diagnosed in Canada

RSV is confirmed with a laboratory test on a sample taken from the nose or throat, most often a nasopharyngeal swab tested by polymerase chain reaction, or PCR. Hospitals commonly use multiplex PCR panels that check for RSV, influenza and SARS-CoV-2 at the same time, and rapid antigen tests are used in some settings. A chest X-ray and a measurement of oxygen in the blood may be added when pneumonia or a flare-up of a lung condition is suspected. Nationally, the Public Health Agency of Canada tracks RSV detections through the Respiratory Virus Detection Surveillance System.

Treatment and management, including immunisation

Clinical research for Respiratory Synctial Virus (RSV) Vaccine is enrolling. See the current studies ↓

Health Canada notes that supportive care is the mainstay for RSV because there is no specific antiviral treatment for it. Care therefore focuses on symptoms, on watching for the lower airway problems that lead to hospital admission, and on the immunisation programmes that exist for people at higher risk. Depending on your age, your other conditions and where you live, a health care team may discuss:

• Supportive care: rest, fluids and over-the-counter medicines for fever
• Hospital care for severe illness, including supplemental oxygen, intravenous fluids and, in some cases, intensive care and ventilation
• Management of the underlying condition when RSV sets off an asthma or COPD flare-up
• RSV vaccines authorised by Health Canada for adults: RSVpreF (Abrysvo) and mRNA-1345 (mRESVIA) for adults 60 and older, and RSVPreF3 (Arexvy) for adults 60 and older and for adults aged 50 to 59 at increased risk. RSVpreF is also authorised for use in pregnancy at 32 to 36 weeks
• Monoclonal antibody products authorised for infants, and publicly funded RSV immunisation programmes, which differ by province and territory

In its statement dated 28 August 2025, the National Advisory Committee on Immunization recommends RSV immunisation programmes for adults aged 75 and older, particularly those with chronic health conditions that raise the risk of severe RSV disease, and for adults aged 60 and older living in nursing homes and other chronic care facilities. For people aged 50 to 74 it describes vaccination as an individual decision made with a health care provider. Whether a given product is publicly funded depends on your province or territory, and these are decisions for you and your own clinician rather than anything this page can settle.

When to talk to a doctor

• Call 911 if you or someone you are caring for has severe trouble breathing, is gasping or grunting, has blue or grey lips or fingertips, becomes confused or very drowsy, or cannot be woken.
• Seek medical care the same day for an infant who is feeding poorly, has fewer wet diapers, is breathing fast or pulling in at the ribs, or has pauses in breathing.
• Contact your clinician if you are 60 or older, or live with a heart or lung condition, and a cold is causing wheeze, breathlessness or a flare-up of your usual symptoms.

Why clinical research matters for RSV

RSV vaccines for older adults are new, and the National Advisory Committee on Immunization has stated that data on severe outcomes such as death and intensive care admission remain limited, as does evidence on how long protection lasts and whether repeat doses are needed. It is also unclear how RSV illness compares with influenza across all age groups, because Canadian comparisons are sparse. Studies now underway include repeat and revaccination schedules, RSV vaccines in adults aged 18 to 59 living with chronic conditions, combination respiratory vaccines, next-generation monoclonal antibodies for infants, and antiviral medicines for people who are already infected.

Those are open questions, and studies are how they close. Taking part is voluntary, the study is explained to you in full during informed consent, and you can withdraw at any time without affecting the care you get from your own doctor or your access to publicly funded immunisation. No one can say in advance whether a study will help you personally.

Learn more from Canadian sources

• Government of Canada: respiratory syncytial virus (RSV)
• NACI: summary of the statement on the prevention of RSV in older adults
• Government of Canada: provincial and territorial immunization information
• Public Health Agency of Canada: Seasonal Respiratory Vaccination Coverage Survey