Human respiratory syncytial virus (RSV) is an enveloped RNA virus first isolated in 1955. The virus belongs to the genus Orthopneumovirus within the family Pneumoviridae. Members of this genus include human RSV, bovine RSV and murine pneumonia virus¹. Human RSV is a globally prevalent cause of lower respiratory tract infection in all age groups. Authors of a study published in 2022 estimate that R.S.V. is responsible for one in 50 deaths of children under the age of 5 across Europe². It is the most common cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia (infection of the lungs) in children younger than 1 year of age in the United States. The global burden of RSV infection and epidemiological patterns of virus circulation, remain understudied³.

In infants and young children, the first infection may cause severe bronchiolitis that can sometimes be fatal. In older children and adults without underlying conditions, repeated upper respiratory tract infections are common and range from subclinical infection to symptomatic upper respiratory tract disease⁴. In addition to its prevalence in pediatric populations, RSV is increasingly being recognized as an important pathogen in older adults, with infection leading to an increase in hospitalization rates among those aged 65 years and over, and to increased mortality rates among the frail elderly similar to rate seen for influenza. The risk of severe disease in adults is increased by the presence of underlying chronic pulmonary disease, circulatory conditions and functional disability, and is associated with higher viral loads. RSV is also a threat both to young infants and among immunocompromised and vulnerable individuals in healthcare and long term care environments. High mortality rates have been observed in those infected with RSV following bone marrow or lung transplantation⁴.

WHAT ARE THE SYMPTOMS?

People infected with RSV usually show symptoms within 4 to 6 days after getting infected. Symptoms of RSV infection usually include

• Runny nose
• Decrease in appetite
• Coughing
• Sneezing
• Fever
• Wheezing

These symptoms usually appear in stages and not all at once. In very young infants with RSV, the only symptoms may be irritability, decreased activity, and breathing difficulties⁵.

RSV can also cause more severe infections such as bronchiolitis, an inflammation of the small airways in the lung, and pneumonia, an infection of the lungs.

For severe RSV infection, especially in older adults and infants younger than 6 months of age, hospitalization may be required if they are having trouble breathing or are dehydrated. In the most severe cases, a person may require additional oxygen, or IV fluids (if they can’t eat or drink enough), or intubation (have a breathing tube inserted through the mouth and down to the airway) with mechanical ventilation (a machine to help a person breathe). In most of these cases, hospitalization only lasts a few days⁵.

HOW IS IT TRANSMITTED?

RSV can spread when

• An infected person coughs or sneezes
• You get virus droplets from a cough or sneeze in your eyes, nose, or mouth
• You have direct contact with the virus, like kissing the face of a child with RSV
• You touch a surface that has the virus on it, like a doorknob, and then touch your face before washing your hands

People infected with RSV are usually contagious for 3 to 8 days and may become contagious a day or two before they start showing signs of illness. However, some infants, and people with weakened immune systems, can continue to spread the virus even after they stop showing symptoms, for as long as 4 weeks. Children are often exposed to and infected with RSV outside the home, such as in school or childcare centers. They can then transmit the virus to other members of the family⁴.

RSV can survive for many hours on hard surfaces such as tables and crib rails. It typically lives on soft surfaces such as tissues and hands for shorter amounts of time⁴.

People are typically infected with RSV for the first time as an infant or toddler and nearly all children are infected before their second birthday. However, repeat infections may occur throughout life, and people of any age can be infected. Infections in healthy children and adults are generally less severe than among infants and older adults with certain medical conditions. People at highest risk for severe disease include

• Premature infants
• Young children with congenital (from birth) heart or chronic lung disease
• Young children with compromised (weakened) immune systems due to a medical condition or medical treatment
• Children with neuromuscular disorders
• Adults with compromised immune systems
• Older adults, especially those with underlying heart or lung disease

In the Northern Hemisphere, RSV circulation generally starts during fall and peaks in the winter. The timing and severity of RSV circulation in a given community can vary from year to year.

HOW IS IT CONTROLLED?

There are steps you can take to help prevent the spread of RSV. Specifically, if you have cold-like symptoms you should

• Cover your coughs and sneezes with a tissue or your upper shirt sleeve, not your hands
• Wash your hands often with soap and water for at least 20 seconds
• Avoid close contact, such as kissing, shaking hands, and sharing cups and eating utensils, with others
• Clean and disinfect frequently touched surfaces such as doorknobs and mobile devices using a disinfectant effective against RSV and approved by the national or international authority or regulating body. For example, in the US, use an EPA-registered disinfectant with a claim against RSV and in the EU, use a disinfectant labeled with either ‘Virucidal’, ‘Limited Spectrum Virucidal’ or ‘Virucidal Activity against enveloped viruses’ activity⁶. Always follow the manufactures use instructions, including concentration, application and contact time.

Researchers are working to develop RSV vaccines, but none are available yet. A drug called palivizumab (pah-lih-VIH-zu-mahb) is available to prevent severe RSV illness in certain infants and children who are at high risk for severe disease. This could include, for example, infants born prematurely or with congenital (present from birth) heart disease or chronic lung disease. The drug can help prevent serious RSV disease, but it cannot help cure or treat children already suffering from serious RSV disease, and it cannot prevent infection with RSV.

In the EU a drug called Nirsevimab, sold under the brand name Beyfortus, was approved for use in late 2022. It is a human recombinant monoclonal antibody with activity against or RSV for infants. Nirsevimab is designed to bind to the fusion protein on the surface of the RSV virus⁷.

REFERENCES AND FURTHER INFORMATION 

¹Respiratory Syncytial Virus: Virology, Reverse Genetics, and Pathogenesis of Disease - PMC (nih.gov)

²The burden of respiratory syncytial virus in healthy term-born infants in Europe: a prospective birth cohort study - The Lancet Respiratory Medicine.

³RSV burden of disease workshop 23-24 Nov 2015 report (europa.eu)

⁴Respiratory Syncytial Virus (RSV) disease (who.int)

⁵RSV (Respiratory Syncytial Virus) | CDC

⁶Explanation of virus claims for disinfectants | Biocides | Board for the Authorisation of Plant Protection Products and Biocides (ctgb.nl)

⁷New medicine to protect babies and infants from respiratory syncytial virus (RSV) infection | European Medicines Agency (europa.eu)