RSV

Respiratory syncytial virus (RSV) is a viral pathogen known for causing respiratory infections, predominantly affecting the lungs and airways. It often causes a mild cough and cold but, in some people, can trigger pneumonia or bronchiolitis, characterised by inflammation in the airways.

RSV is very common. Globally, it infects up to 90% of children within the first two years of life and frequently reinfects older children and adults, and is more common during winter, especially in temperate countries like the UK.

According to a recent study, there are roughly 33 million cases, 3.6 million hospital admissions, and 100,000 deaths caused by RSV globally each year in children under five years of age. It is the second largest infectious cause of death in children under one year of age, after malaria.

Despite developing antibodies after an infection, individuals remain susceptible to RSV infection throughout life. Infants under six months of age, people with weak immune systems, and the elderly are at the highest risk, with severe cases potentially leading to hospitalisation. Adult infections are often undiagnosed, particularly in the elderly, leading to an underestimated number of cases.

In healthy adults, RSV infection typically develops with cold-like symptoms such as runny nose, sneezing, nasal congestion, cough, and sometimes fever.

In children, it can also lead to ear infections and croup, characterized by a barking cough due to upper airway inflammation.

Bronchiolitis, affecting the small airways in the lungs, is a common and serious consequence in babies and infants, making breathing difficult and feeding challenging.

Children under one year of age, the elderly, and those with weak immune systems are at increased risk of severe RSV symptoms. RSV infection can cause pneumonia or even death.

In temperate regions like the UK, RSV causes outbreaks each year. Epidemics typically begin in October and last for four to five months, reaching their peak in December in the UK.

Laboratory reports of infections due to respiratory syncytial virus, England and Wales by date of report 1991-2013

Source: The Green Book

RSV spreads when someone who is infected coughs or sneezes, releasing large droplets that carry the virus. It can also be caught by touching things that have the virus on them, like door handles or toys, and then touching the face. Once exposed to the virus, it takes about three to five days for symptoms to begin.

RSV transmission can be reduced by thorough handwashing and keeping surfaces that are often touched clean. It is usually best for people with a cold, or other respiratory illnesses to avoid contact with those at risk where possible. 

From 1st September 2024, RSV vaccination will be available in the UK for older adults 75 to 79 years of age, and for pregnant women who are at least 28 weeks pregnant to protect their infants. See our vaccine page for more information.

Currently, the primary approach to RSV care is supportive, involving measures like administering fluids and oxygen as necessary. Although there is one licensed antiviral drug for RSV, its usage is uncommon due to concerns regarding drug toxicity and limited efficacy.

In severe cases, intensive care may be required, including artificial ventilation. Tragically, almost all infant fatalities from RSV occur in developing countries where access to such costly care is limited.

Passive immunisation, using a monoclonal antibody (mAb) called Palivizumab that mimics the immune system’s ability to fight off RSV, is available to protect very high-risk infants for whom RSV infection is likely to cause serious illness or death, such as those with severe underlying lung or heart disease, and all children less than 24 months of age with severe combined immunodeficiency syndrome (SCID).

A new mAb, called nirsevimab, that could be used widely has recently been licensed. In addition, there is a licensed RSV vaccine for pregnant women, to protect their infants, and two licensed vaccines to prevent RSV in older adults.