Respiratory syncytial virus, or RSV, is one of the most common causes of respiratory infections in people of all ages. Most infections produce cold-like symptoms, such as a runny nose, coughing, sneezing, or fever, and many people recover within one to two weeks. However, in infants, young children, older adults, and people with certain underlying conditions, the infection may spread to the lower respiratory tract and cause bronchiolitis or pneumonia.

RSV requires particular attention because infants may not show obvious cold symptoms. Instead, they may initially feed less, become irritable or unusually sleepy, or develop abnormal breathing. Recognizing the symptoms and warning signs can help caregivers seek appropriate medical care promptly.

What Is RSV?

RSV stands for respiratory syncytial virus. It infects the respiratory tract, including the nose, throat, airways, and lungs. People of all ages can become infected, and previous infection does not provide complete protection against future infections. Therefore, a person can become infected with RSV more than once.

Nearly all children are likely to experience at least one RSV infection during their first two years of life. Most children develop mild, cold-like symptoms. However, some infants, particularly very young or premature babies, may develop bronchiolitis, an inflammation of the small airways in the lungs. When these airways become swollen and filled with mucus, the child may breathe rapidly, have difficulty breathing, or develop wheezing.

In adults, RSV infection also generally produces cold-like symptoms. However, older adults, people with weakened immune systems, and those with chronic heart or lung conditions may face a higher risk of pneumonia or other serious complications.

How Does RSV Spread?

RSV can spread from one person to another through respiratory secretions. When an infected person coughs or sneezes, virus-containing droplets may enter the eyes, nose, or mouth of someone nearby. Direct contact, such as hugging or kissing the face of an infected child, may also transmit the virus.

The virus can also spread when a person touches a contaminated object or surface, such as a doorknob, table, toy, or crib rail, and then touches their face without washing their hands. Sharing cups, spoons, towels, or other personal items may therefore increase the risk of transmission.

Most people with RSV can transmit the virus for approximately three to eight days and may become contagious before symptoms appear. However, some infants and people with weakened immune systems may continue spreading the virus for several weeks, even after their symptoms have improved.

Settings where children gather, such as nurseries, schools, and childcare centers, allow RSV to spread easily. Children exposed outside the home may then transmit the virus to their parents, grandparents, or other household members.

Symptoms to Watch For

RSV symptoms usually begin approximately four to six days after exposure. They may appear gradually rather than developing all at once. Common symptoms include a runny or blocked nose, coughing, sneezing, fever, sore throat, reduced appetite, fatigue, and wheezing.

In very young infants, symptoms may differ from those seen in older children and adults. Some babies may not have a fever or obvious cold symptoms. Instead, they may become unusually irritable, feed less, move less, appear drowsy, or begin having difficulty breathing. Some infants, particularly those born prematurely, may experience brief pauses in breathing.

If the infection spreads to the lower respiratory tract, the patient may develop a worsening cough, rapid breathing, wheezing, fatigue, or increased effort when breathing. In infants, caregivers may notice flaring nostrils, retractions of the chest or the area below the ribs, or difficulty feeding because the baby must repeatedly stop sucking to breathe.

Some older adults may not develop a fever or prominent respiratory symptoms. Instead, they may experience fatigue, reduced appetite, confusion, or worsening of an existing condition, such as increased breathing difficulty from chronic obstructive pulmonary disease or worsening fatigue and swelling from heart failure.

Who Is at Risk of Severe Illness?

Although people of all ages can contract RSV, infants younger than six months and babies born prematurely are at greater risk of severe illness. Their airways are smaller and their immune systems are not yet fully developed. Even minor swelling or mucus buildup can therefore have a significant effect on their breathing.

Children with congenital heart disease, chronic lung disease, or weakened immune systems require particular attention. Older adults, especially those who are frail or live in long-term care facilities, also have a higher risk of pneumonia and other RSV-related complications.

People with asthma, chronic obstructive pulmonary disease, heart disease, or compromised immunity may experience severe symptoms or worsening of their underlying conditions. Exposure to tobacco smoke and air pollution may also irritate the airways and increase the risk of severe respiratory symptoms in children.

When Should You Seek Emergency Medical Care?

Take the patient to a hospital immediately if they have difficulty breathing, shortness of breath, abnormally rapid breathing, chest or lower-rib retractions, flaring nostrils, or unusually noisy breathing. Bluish or grayish lips, face, fingertips, or toes may indicate that the body is not receiving enough oxygen and requires emergency care.

Infants who have pauses in breathing, cannot feed, produce less urine, become unusually drowsy, are difficult to wake, or do not respond normally should receive prompt medical assessment. A dry mouth, an absence of tears when crying, or a nappy remaining dry for longer than usual may indicate dehydration.

Older children and adults should seek hospital care if they experience chest pain or pressure, difficulty breathing, dizziness, confusion, an inability to drink enough fluids, or rapidly worsening symptoms. Older adults and people with heart disease, lung disease, or weakened immunity should consult a doctor promptly if they develop concerning symptoms.

Diagnosing RSV Infection

A doctor may diagnose RSV by reviewing the patient’s symptoms and possible exposure history and performing a physical examination. The assessment may include evaluating the breathing pattern and respiratory rate, listening to the lungs, measuring blood oxygen levels, checking for dehydration, and determining whether the patient can drink or feed adequately.

For some patients, particularly those with severe symptoms, risk factors, or a need for hospitalization, the doctor may collect a sample of nasal secretions and test it for RSV using an antigen or molecular test.

Chest X-rays and blood tests are not necessary for every patient. A doctor may order them if pneumonia, complications, or another illness with similar symptoms, such as influenza or COVID-19, is suspected.

Treatment and Care

Most people with RSV improve without specific treatment within one to two weeks. Care focuses on relieving symptoms, maintaining adequate hydration and oxygen levels, and monitoring for worsening illness.

Antiviral medication is not routinely used to treat RSV in the general population. Antibiotics cannot eliminate the virus and are used only if a doctor suspects or confirms a concurrent bacterial infection.

Patients with severe symptoms may require hospitalization. Treatment may include supplemental oxygen, removal of nasal secretions, intravenous fluids when the patient cannot drink or feed adequately, and respiratory support for those who develop respiratory failure. The treatment approach depends on the patient’s age, symptom severity, underlying conditions, and the doctor’s clinical judgment.

If the illness is mild enough to be managed at home, the patient should get adequate rest, drink fluids regularly, and have their breathing monitored closely. Infants may benefit from smaller, more frequent feeds. When nasal congestion is present, saline nose drops and appropriate removal of nasal secretions may help the child breathe and feed more comfortably.

Fever reducers and other symptom-relieving medicines should be used according to the advice of a doctor or pharmacist. Aspirin should not be given to children. Caregivers should not give children cough medicines, antibiotics, or other medications without professional advice, as some products may be unsuitable for their age or may cause adverse effects.

Preventing RSV and Reducing Its Spread

Regularly washing hands with soap and water is a fundamental way to reduce the spread of RSV. People should avoid touching their eyes, nose, and mouth with unwashed hands and cover their mouth and nose with a tissue or the inside of their elbow when coughing or sneezing.

Toys, doorknobs, tables, crib rails, and other frequently touched surfaces should be cleaned regularly. Cups, spoons, towels, and personal items should not be shared. People with respiratory symptoms should stay home when possible, avoid close contact with infants, older adults, and people with weakened immune systems, and improve indoor ventilation where practical.

Parents and other household members should avoid smoking or using electronic cigarettes around children. Smoke and other irritants can affect the respiratory tract and may increase the risk of severe symptoms.

Vaccines and long-acting preventive antibodies are now available to reduce the risk of severe RSV disease in certain groups, including pregnant women, infants, older adults, and people with particular risk factors. However, approved products, eligible groups, and immunization recommendations vary between countries. Anyone interested in these preventive options should consult a doctor to assess their suitability and confirm the current recommendations and availability in Thailand.

Summary

RSV is a respiratory virus that can infect people of all ages. Most infections cause cold-like symptoms and resolve without specific treatment. However, infants, young children, older adults, and people with certain underlying conditions may develop bronchiolitis, pneumonia, or other serious complications.

Handwashing, cleaning frequently touched surfaces, avoiding the sharing of personal items, limiting close contact with others while ill, and protecting children from tobacco smoke may help reduce transmission. Caregivers should monitor the patient’s breathing, feeding, urine output, and responsiveness. If the patient develops breathing difficulty, bluish skin, pauses in breathing, an inability to feed or drink, or unusual drowsiness, they should be taken to a hospital immediately.

Prepared by: ภญ. ปุณยนุช อังคะนาวิน

References

1. World Health Organization. Respiratory syncytial virus (RSV)
2. Centers for Disease Control and Prevention. Symptoms and Care of RSV
3. National Health Service. Respiratory syncytial virus (RSV)