Respiratory Syncytial Virus (RSV)

Information for parents and carers on caring for unwell children and when to seek medical assistance is available at: MyChild.ie and HSE.ie - How to stay well in winter

What is Respiratory Syncytial Virus?

Respiratory syncytial virus (RSV) is a common respiratory virus that usually causes mild, cold-like symptoms. Most people recover in a week or two, but RSV can be serious, especially for infants, young children and older adults.

RSV causes coughs and colds every winter and is the most common cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia (lung infection) in infants under 1 year of age. It is also the most common cause of hospital admissions due to acute respiratory illness in young children aged less than 5 years. One to two out of every 100 children younger than 6 months with RSV infection may need to be hospitalised.

By two years of age, nearly all children have been infected with RSV at least once. The antibodies that develop following RSV childhood infection do not prevent further infections throughout life. RSV is a significant cause of infection and outbreaks in hospitals, neonatal units, day units and nursing homes.

RSV has been a notifiable disease in Ireland since January 2012. RSV activity in Ireland is monitored by the HSE-Health Protection Surveillance Centre (HPSC).

Explore a weekly epidemiological summary of RSV data in Ireland in the Respiratory Virus Notification Data Hub. The latest surveillance reports on RSV and other seasonal respiratory viruses, including influenza, are available on the HPSC website. RSV notifications are also reported in the Infectious Disease Weekly Report, and RSV outbreaks are reported in the Weekly Outbreak Report.

When does Respiratory Syncytial Virus circulate?

RSV outbreaks typically occur in the winter months with the highest numbers of infections usually reported in December and January every year. The sharp winter RSV peak varies little in timing or size from one year to the next, in contrast to influenza which is much less predictable in its timing. However, during the 2021/22 season, RSV activity started in early October and peaked during mid November. During 2022/2023 season, RSV circulation also began in early October and remained at high levels during all of November. This trend was also seen internationally and appears to be the trend since the COVID-19 pandemic.

How is Respiratory Syncytial Virus spread?

RSV is highly contagious. The infectious period lasts from shortly before onset of symptoms to one week after the onset of symptoms. However, even after recovery, very young infants and children with weakened immune systems can continue to spread the virus for up to four weeks. Most children recover from illness in 8 to 15 days.

RSV is spread by large droplets and by secretions from contact with an infected person. The virus multiplies (grows) in the eyes, nose and airway passages and usually spreads from one person to another when people infected with RSV cough, sneeze, or spit. These droplets can land on the mouths or noses of people who are nearby and cause them to catch the RSV infection.

RSV can survive on hard surfaces/objects (e.g. worktops, doorknobs) for 4-7 hours. It typically lives on soft surfaces such as tissues and hands for shorter periods of time. Spread can occur indirectly through contact with RSV-contaminated hands, handkerchiefs, eating utensils or other objects or surfaces. A person can get RSV by touching a surface or object with RSV on it (e.g. a doorknob) and then touching their mouth, nose, or eyes.

The incubation period for RSV (the time between exposure to RSV infection and the appearance of symptoms) ranges from 2 to 8 days, but is usually 4 to 6 days.

What are the symptoms of Respiratory Syncytial Virus?

Symptoms can appear between 2 to 8 days after a person is infected and include the following:

• Fever
• Runny nose
• Sneezing
• Cough and sometimes croup (a barking cough caused by inflammation of the upper airways)
• Wheezing
• Decreased appetite
• Ear infections (in children)

In very young infants, irritability, decreased activity and breathing difficulties may be the only symptoms of infection. Lower respiratory tract infection, such as bronchiolitis, pneumonia or pneumonitis, are most likely to occur during a child's first infection with RSV.

Immunity is incomplete and short-lived with RSV. Repeated respiratory infections can occur, though these are usually mild and become less common with increasing age. Although RSV is primarily a childhood infection, it can occur at any age and may be severe in older persons.

Who is most at risk?

Although RSV is primarily a childhood infection, it can occur at any age and can be most severe in the very young (under one year of age), the immunocompromised (those with weakened immune systems), and in those aged 65 years and older.

Premature infants, infants (especially those 6 months and younger), children less than 2 years of age with congenital heart or chronic lung disease, children with  weakened immune systems due to a medical condition or medical treatment and children with neuromuscular disorders are at the highest risk of severe RSV disease.

The highest rates of hospitalisation with RSV occur in children aged 0-4 years. Most otherwise healthy infants infected with RSV do not need to be hospitalised and for cases who are hospitalised, their stay in hospital usually only lasts a few days.

Adults with weakened immune systems, adults with chronic heart and lung disease and those aged 65 years and older are also at increased risk of severe RSV disease. However, only a minority of adult infections are diagnosed, as RSV is not widely recognised as a cause of respiratory infections in adults. Elderly patients are frequently not investigated microbiologically, as there are fewer viruses present in their respiratory secretions compared with children. This results in the number of adult infections being underestimated.

Laboratory testing

Reverse transcriptase-polymerase chain reaction (RT-PCR) assays are currently the gold standard in RSV testing and are available commercially. These are more sensitive than antigen detection and virus isolation methods.

How is it treated?

• No specific treatment other than treatment of symptoms - i.e. paracetamol to reduce temperature is necessary for children with mild illness. Children with severe respiratory illness will require hospitalisation and oxygen therapy.
• Antiviral Medicines: Ribavirin is licensed for the treatment of RSV and its use for the treatment of RSV may be considered for a small number of patients with severe illness. Treatment of RSV with Ribavirin should be done under the supervision of an infection specialist - e.g. a consultant microbiologist or an infectious diseases physician
• Antibiotics are not effective against RSV and it is important that unnecessary antibiotics are discontinued once a diagnosis of RSV infection is confirmed, to avoid adverse drug reactions and the promotion of antibiotic resistance.

Prevention

• Frequent, careful handwashing is the most important measure in preventing the spread of RSV.
• To reduce spread, it is important that if someone has cold-like/flu-like symptoms that they cover their nose and mouth (preferably with a tissue) when they cough and sneeze, and wash their hands afterwards for at least 10 seconds or use an alcohol-based rub/gel. Tissues need to be bagged and disposed of appropriately (in a rubbish bin) if they are used outside the home, otherwise, they can be disposed of in normal household waste. See HPSC website for instructions.
• Avoiding sharing items such as cups, glasses and utensils with persons who have RSV illness should decrease the spread of the virus to others.
• In addition, cleaning contaminated (soiled with RSV) surfaces (such as door handles) may help stop the spread of RSV. Normal household products can be used.
• In the hospital setting, RSV transmission can be prevented by:
  • Managing children with RSV together in the same ward
  • Strict attention to handwashing recommendations
  • Barrier precautions, such as gowns and gloves, may be required
  • Avoiding overcrowding
  • Restricting visiting if necessary
• In other settings: Persons ill with RSV should not attend crèches, work, school and non-residential institutions until well. Try to avoid young infants, frail older persons and immunocompromised (weakened immune systems) persons coming into contact with individuals with respiratory infection.

Prophylaxis

• Antibodies against RSV: Palivizumab, a monoclonal antibody therapy, is licensed in Ireland for the prevention of serious lower respiratory tract infection caused by RSV in infants at high risk of infection. If your child is at high risk for severe RSV disease as outlined above, talk to your healthcare provider to see if palivizumab can be used as a preventive measure.
• In 2023, the European Union approved the first RSV vaccine for pregnant women as well as two vaccines for older adults. These vaccines are currently under review for use in national vaccination programmes.

Last reviewed: 17 November 2023