The RSV infection: To be monitored in infants, young children, and those over 60 years old

Respiratory syncytial virus (RSV) is a very common respiratory virus, similar to influenza (flu virus) and SARS-CoV-2 (COVID-19). It is often the cause of lung and upper respiratory tract infections during the colder months of the year, from late September to early spring [1].

RSV is extremely contagious. It is estimated that by the age of two, most children will have been infected with RSV. It can spread through contaminated droplets in the air (e.g. coughing or sneezing) or through contact with hard surfaces, where the virus can survive for several hours. As a result, babies and young children can contract the virus in daycare centres, at home or in any other place where infected people are present.

Respiratory syncytial virus is responsible for many infections of the respiratory tract and lungs, but these are usually mild. However, in some people at risk, RSV infections can lead to complications. Each year, they lead to more than 2 million medical consultations and up to 80,000 hospitalizations in children under 5 years old in the United States. In adults over 60, the number of hospitalizations due to the virus is estimated to be between 100,000 and 160,000 [2]. In Canada, the number of hospitalizations due to RSV is estimated at 18 cases per 100,000 people [3].

Children under 2 years old are among the groups most likely to be severely affected by RSV. Upon first exposure to the virus, 25% to 50% of children show symptoms of bronchiolitis or pneumonia, and 0.5% to 3% are hospitalized, with the vast majority being under 6 months old [4]. In addition to infants, children under 1 year old, those born prematurely, and children under 2 with chronic lung or heart disease, as well as those weakened by a compromised immune system, are at particularly high risk of hospitalization.

In most children, the symptoms of RSV infection resemble those of a common cold and should disappear over time. [6] These are:

• Runny nose
• Throat irritation
• Cough
• Headache (mild)
• Fever (sometimes)
• Fatigue
• Loss of appetite

However, if the child has faster or wheezing breaths, if the skin pulls in between the ribs when they inhale, or if their overall condition deteriorates, RSV could be causing complications. Pay particular attention to the following symptoms, which indicate bronchiolitis, an inflammation of the small airways leading to the lungs, very common in infants [5]:

• Shallow cough
• Wheezing
• Rapid breathing
• Restlessness
• Elevated heart rate
• Intercostal retractions (hollows between the ribs, at the base of the neck, or above the collarbones when the child breathes)
• Nasal flaring (widening of the nostrils while breathing)
• Wheezing sounds heard in the lungs (with a stethoscope or by ear)

The diagnosis of an RSV infection – and a complication such as bronchiolitis – is primarily based on the clinical picture (signs and symptoms in combination with the patient's age and the season). This diagnosis can be confirmed by laboratory analysis of nasopharyngeal secretions, which are collected at the intersection of the mouth and nose passages:

• Test for virus antigens by immunoassay
• Viral culture of secretions
• Test for viral nucleic acids using an amplification technique (respiratory multiplex PCR)

Most often, an RSV infection, even when accompanied by bronchiolitis, clears up on its own without any particular treatment within one or two weeks. No antibiotics are necessary since the infection is caused by a virus, not bacteria. However, it is possible to relieve the child by removing nasal secretions (by blowing the nose regularly), encouraging frequent fluid intake, and giving acetaminophen to reduce fever, if required.

More severe cases of bronchiolitis, which most often affect children who are particularly at risk (infants, premature newborns, and children under 2 with chronic illness or immune deficiencies), may require hospitalization or respiratory support.

Since the fall of 2024, a new preventive agent, nirsevimab (Beyfortus), a monoclonal antibody administered in a single dose via intramuscular injection, is offered free of charge, in particular to infants under 6 months old, before (or during) their first exposure to the virus. Studies have shown that a single dose of nirsevimab can reduce the risk of RSV-related hospitalization by at least 70% during the peak RSV season [6].

Before the introduction of nirsevimab, another monoclonal antibody, palivizumab (Synagis), was administered to infants at risk of complications. It had to be given in four or five doses every 28 days before and during the infection season [7].

Additionally, a vaccine, Abrysvo, has been available since May 2024 to prevent RSV infections [8]. It can be administered to pregnant women between the 32nd and 36th weeks of pregnancy (regardless of the season) to allow the transfer of anti-RSV antibodies from the mother to the fetus [9].

Two vaccines are authorized in Canada for the vaccination of adults (Abrysvo and Arexvy). They are offered free of charge in Quebec to certain groups, including people over 60 years old living in long-term care facilities (CHSLD) and other intermediate resources. These vaccines are recommended (but not currently administered for free) for people over 75 years old living with a chronic illness. They are also approved for all individuals over 60 years old [9].

RSV infection does not confer immunity, and monoclonal antibody injections provide protection only for a single season at most [10]. Prevention remains the most effective approach to avoid RSV infections and their complications. These recommendations are the same for all respiratory viruses, including SARS-CoV-2 and the flu virus.

• Wash your hands regularly, especially before tending to your child.
• Make sure your children wash their hands often to reduce the spread of germs.
• Wear a mask if you have a cold.
• Avoid being near people who have a cold, especially if you have a baby under six months old.
• Clean and disinfect hard surfaces frequently.
• Vaccinate family members living with the child against the flu.

This updated version of the article represents a revision of the originally published article on our website. We have considered recent developments to provide you with up-to-date and relevant information.

We offer services that can help your doctor diagnose RSV and determine the appropriate treatment.

• Respiratory multiplex PCR

Do you have a medical prescription for this test? Please book an appointment online or call customer service for Biron Health Group at 1-833-590-2712.