In focus: RSV in adults

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Reference: October 2025 | Issue 10 | Vol 11 | Page 35

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Respiratory syncytial virus (RSV) is a highly infectious virus that primarily affects the respiratory system. While it most commonly impacts infants and young children, it can also cause severe illness in adults, particularly those with underlying medical conditions.¹

RSV is responsible for a range of respiratory illnesses, from mild cold-like symptoms to more severe complications, including pneumonia and bronchiolitis. It spreads through respiratory droplets produced by coughing and sneezing, as well as through direct contact with contaminated surfaces. The virus can survive on surfaces for several hours, which increases its potential for transmission.^1,2

In adults, RSV can present similarly to a common cold or influenza. However, in certain high-risk populations, it can lead to severe respiratory distress, hospitalisation, or even death. Over the past 10 years, RSV has gained recognition as a significant contributor to acute respiratory illness in older adults globally.^1,2

Observational studies in adult populations have shown that RSV incidence increases with advancing age and is higher among those with underlying high risk conditions.³ Adults aged 60 years and older with chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF) have at least twice the risk of severe complications from RSV infection compared to those without these underlying conditions.^3,4 The incidence of adult RSV cases tends to rise during the colder months, as the virus thrives in colder and drier environments.^1,3

Since January 2012, RSV has been classified as a notifiable disease in Ireland. The HSE Health Protection Surveillance Centre (HPSC) is responsible for monitoring RSV activity across the country. ⁵

How common is RSV in adults?

RSV infections in adults are increasingly recognised and can lead to significant illness, particularly in vulnerable populations.⁴ The incidence peaks during the winter months, coinciding with higher viral circulation, and healthcare services frequently experience increased demand due to exacerbations of underlying conditions such as asthma or COPD.

In susceptible adults, RSV can worsen these chronic illnesses, resulting in more severe disease and higher rates of hospitalisation.^1,2,3 Due to an ageing population, the effects of immunosenescence, and the growing burden of comorbidities, high income countries face an increasing risk of RSV epidemics.^1,4

In 2022, almost 4,000 children in Ireland aged four years and younger were diagnosed with RSV, with 2,500 requiring hospitalisations. Most of these admissions, and almost all ICU admissions, occurred in children under one year of age. RSV continued to circulate in high levels during the 2023/2024 season, with a total of 1,397 hospital admissions and 118 PICU admissions in infants under one year of age.

Over 1,500 adults aged 65 years and older tested positive for RSV in 2022. Of these, nearly 150 were admitted to hospital.⁵ The HSE HPSC notes that RSV is often underdiagnosed in adults, as it is not widely recognised as a significant cause of respiratory infections in this population.⁶

In elderly patients, microbiological testing is less frequently performed, partly due to lower viral loads in respiratory secretions compared to children. As a result, the true burden of RSV in adults in Ireland is likely underestimated.⁶

Comprehensive data on RSV epidemiology in Ireland is available on the HPSC Respiratory Virus Notification Data Hub (respiratoryvirus.hpsc.ie).⁷

Symptoms of RSV in adults

RSV infection in adults can present with a broad range of symptoms, from mild, self-limiting signs resembling a common cold or influenza, to severe respiratory complications. Typical symptoms include nasal congestion, sore throat, persistent cough, low-grade fever, shortness of breath, wheezing, and fatigue.

In healthy adults, these symptoms are usually manageable, although they can cause significant discomfort and disrupt daily activities. In high-risk populations, such as older adults, individuals with chronic lung or heart disease, and those with weakened immune systems, RSV can lead to serious complications, including pneumonia, bronchiolitis, or acute respiratory distress syndrome (ARDS), often necessitating hospitalisation and intensive care.

Severe infections can exacerbate pre-existing conditions and increase morbidity. They also place additional strain on healthcare resources, highlighting the need for timely recognition, supportive care, and preventive strategies.^{1, 5,6}

High risk groups

Certain adult populations are at higher risk of severe RSV complications. Older adults, particularly those aged 65 and above, are more likely to develop serious respiratory issues due to a weakened immune system and comorbidities. Chronic respiratory conditions such as COPD and asthma, as well as cardiovascular diseases, increase the likelihood of severe disease, which may result in exacerbations, acute respiratory failure, or the need for mechanical ventilation.^1,5,6

Adults with immunocompromised systems, due to conditions such as cancer, HIV/AIDS, or organ transplants, are also at greater risk. These individuals often experience prolonged infections due to reduced viral clearance. Pregnant women, while not universally considered high risk, may have an increased risk of complications due to physiological changes affecting immune and respiratory systems during pregnancy.^1,5,6

Management of RSV in adults

Management of RSV in adults is mainly supportive, focusing on symptom relief and maintaining overall health, particularly in those with more severe infections. For individuals with mild illness, over-the-counter medications such as paracetamol or ibuprofen can help reduce fever and alleviate discomfort.

Symptomatic relief for nasal congestion can be achieved with decongestants or saline nasal sprays, while ensuring adequate hydration is essential to prevent fluid depletion and support recovery. Additional measures, such as rest and avoidance of respiratory irritants, can further aid symptom management and reduce the risk of complications.^5,6

In more severe cases, where RSV leads to pneumonia, bronchiolitis, or ARDS, hospitalisation may be required. Treatment in such cases can include oxygen therapy to help alleviate respiratory distress and administration of IV fluids for dehydration. For individuals with severe difficulty breathing, mechanical ventilation may be necessary.^5,6

Although there are no specific antiviral medications approved for treating RSV in adults, certain treatments may be used in highly immunocompromised individuals. Ribavirin is an antiviral medication approved for RSV treatment in certain EU Member States and the US.⁵ Its use for the treatment of RSV may be considered for a small number of patients with severe illness.

Ribavirin should only be used under the supervision of an infection specialist.⁶ In some cases, corticosteroids may be administered to reduce inflammation and manage airway obstruction. Antibiotics are not effective against RSV and it is important that unnecessary antibiotics are discontinued once a diagnosis of RSV infection is confirmed.⁶

Prevention

Preventing RSV infection in adults primarily involves reducing exposure to the virus and managing risk factors. Standard hygiene measures, including frequent hand washing, avoiding close contact with individuals who exhibit respiratory symptoms, and disinfecting surfaces in shared environments, are important in preventing the spread of RSV.

In June 2024, the Minister for Health announced the launch of the infant RSV Immunisation Pathfinder Programme. As part of this initiative, all newborns born between 1 September 2024 and February 2025 were eligible to receive nirsevimab, with an estimated 28,000 infants expected to be immunised during the 2024-2025 RSV season.

Nirsevimab has been approved by the European Medicines Agency (EMA), and is recommended by the Department of Health, the HSE and the National Immunisation Advisory Committee (NIAC).⁸ Nirsevimab is a long-acting monoclonal antibody approved for passive immunisation of neonates and infants during their first RSV season to prevent RSV-associated lower respiratory tract infection (LRTI). Administered as a single intramuscular injection, it provides at least five months of protection.^5,8,9

In 2025, the national RSV immunisation programme in Ireland introduced significant changes, expanding protection for infants beyond the initial 2024-2025 pilot. From 1 September 2025 to 28 February 2026, all newborns will be offered nirsevimab in maternity hospitals before discharge, ensuring immediate protection against RSV as they enter their first season.¹⁰

In addition, infants born between March and August 2025 will be eligible for immunisation through community-based ‘catch-up’ clinics in early autumn, guaranteeing broader coverage for those who might otherwise miss protection during their first RSV season. Alongside infant immunisation, maternal vaccination with RSVpreF is also available in Ireland, and is recommended during pregnancy to provide passive protection to newborns through transplacental antibody transfer.¹⁰ Together, these measures reflect a growing public health emphasis on early and layered protection for infants, given the high burden of RSV disease in this age group.

Vaccination remains one of the most effective means of preventing severe RSV infections. Currently in Ireland, a small number of children who are at high risk of severe disease are offered palivizumab to protect them from RSV. Palivizumab is a monoclonal antibody for high-risk groups such as infants and children born prematurely or those with underlying health conditions. Palivizumab provides passive immunity by offering to protect vulnerable individuals from severe RSV infection.^8,9 It is administered once monthly, as an intramuscular injection, during the RSV season.⁵

Palivizumab and nirsevimab are not vaccines. They are laboratory-made antibodies that provide passive immunity (pre-formed antibodies) and do not induce an active immune response as vaccines do.⁹

There is currently no widely available RSV vaccine for adults, although research is ongoing into the development of vaccines that could prevent RSV infection in older adults and those with chronic conditions.^5,6 In 2023, the European Medicines Agency (EMA) approved the first RSV vaccines RSVPreF3 and RSVpreF. These vaccines are approved for use in adults aged 60 years and older and have been given NIAC approval. RSVpreF is also approved for use in pregnant women to provide passive protection for infants.⁵

The Health Information and Quality Authority (HIQA) published a rapid Health Technology Assessment (HTA) on 13 August 2024, evaluating the one-year costs of RSV immunisation for infants (<1 year) and older adults (≥65 years) for the 2025-2026 season.^5,10 The cost for infant immunisation ranged from €9.3 to €19 million, while adult immunisation was estimated at €146 million (≥65 years) and €76.2 million (≥75 years).

Hospital cost offsets were higher for infants, and implementing a new RSV programme would cost €2.3 million. The HTA was submitted to the Minister for Health and the HSE for an interim policy decision, and a full HTA requested to guide long-term RSV immunisation policy.^5,11

NIAC recommendations

In Ireland, the NIAC provides guidance on immunisation practices to reduce the burden of RSV. NIAC recommends RSV vaccination for those aged 65 years and older with either RSVPreF3 or RSV preF, however, a routine RSV vaccine for adults in Ireland is not yet approved/available.¹²

In the absence of a specific vaccine for adults, NIAC highlights the importance of preventive strategies such as hygiene measures and early medical intervention for high-risk groups. For those with underlying conditions or weakened immune systems, prompt treatment is important to mitigate the risk of severe disease.¹²

Ongoing research into adult-specific RSV vaccines may offer additional protection in the future. Until then, continued vigilance in managing risk factors and providing early intervention for high-risk individuals remains key to preventing the severe impact of RSV in adults in Ireland.