Overview

Respiratory syncytial virus (RSV) is one of the most common respiratory infections. In healthy children and adults, it often stays in the upper airways (nose and throat), causing mild illness that looks very much like a common cold. Sneezing, runny nose, and a cough are typical first signs.

However, RSV isn’t always “just a cold.” In certain groups, such as infants, young children, older adults, and people with weakened immunity, it can spread deeper into the lungs. This may lead to more serious illnesses such as bronchiolitis or pneumonia.

How Common Is RSV?

RSV is widespread, infecting nearly all children by age 2, with many experiencing repeat infections due to short-lived immunity. It follows a seasonal pattern, with cases rising in the fall, peaking in winter, and declining by early spring.

In the U.S., RSV is the leading cause of hospitalization for infants, with tens of thousands of young children admitted annually. Older adults are also significantly impacted, with over 100,000 hospitalizations each year.

Symptoms

RSV symptoms typically appear 4–6 days after exposure and often mimic a common cold at first. However, symptoms can worsen, particularly in vulnerable groups. Common symptoms include:

Early symptoms:

• Runny or stuffy nose
• Sneezing
• Loss of appetite

As illness progresses:

• Cough (often within a day or two)
• Fever
• Irritability, fatigue, or low energy

More serious symptoms:

• Wheezing or labored breathing if the infection spreads to the lower airways
• In infants, symptoms may be subtle and show up as poor feeding, unusual fussiness, or even pauses in breathing instead of typical cold signs

Causes

Respiratory syncytial virus (RSV) is an RNA virus in the Paramyxoviridae family. It infects the airways, causing inflammation, mucus buildup, and in some cases narrowing of the small air passages, which can lead to breathing difficulties and complications like bronchiolitis or pneumonia.

RSV is highly contagious and spreads through:

• Respiratory droplets from coughing or sneezing
• Direct contact, such as kissing or touching someone with the virus
• Contaminated surfaces, like toys, doorknobs, or tables. RSV can survive for hours on hard surfaces, and touching these followed by touching your face can lead to infection

Most people are contagious for 3 to 8 days, starting about 1–2 days before symptoms appear. Infants and people with weakened immune systems can spread the virus for several weeks.

Who’s at Risk?

Certain groups face a much higher risk of severe illness from RSV:

• Infants under 6 months, especially premature babies
• Children with chronic lung disease or congenital heart defects
• Older adults, especially those 65 and older
• People with weakened immune systems
• Individuals with asthma, COPD, heart failure, diabetes, or kidney disease
• Those exposed to secondhand smoke
• People in crowded settings like daycare, schools, or nursing homes

Diagnosis

Doctors typically diagnose RSV based on symptoms and seasonal timing. Because RSV can resemble other respiratory viruses, testing may be done, especially in infants, older adults, or those with underlying health conditions.

• Common tests: a nasal swab or small saline wash, most accurately checked using PCR (polymerase chain reaction). Rapid antigen tests are quicker and frequently used in children.
• Severe cases: chest X-ray for pneumonia, blood or urine tests to rule out other infections.

Treatment

Most RSV infections are mild and improve at home with supportive care. Treatment aims to ease symptoms and prevent complications.

For mild illness (most cases):

• Rest and hydration
• Acetaminophen (Tylenol) or ibuprofen (Motrin) for fever or pain
• Nasal saline spray or suction to clear mucus
• Cool-mist humidifier or steamy bathroom for congestion relief

For severe illness, hospital care may include:

• IV fluids for dehydration
• Oxygen therapy if blood oxygen levels drop
• Mechanical ventilation in very severe cases

Medications:

• Antibiotics only if a bacterial infection is present
• Steroids are generally not used unless the patient also has asthma
• Ribavirin, an antiviral, is rarely used and reserved for severely immunocompromised patients

Prevention

Preventing RSV involves both everyday hygiene and medical protection, especially for infants and older adults.

Stress Management

• Frequent handwashing
• Covering coughs and sneezes
• Cleaning shared surfaces
• Staying home when sick

Medical Protection

• For pregnant women: Abrysvo (Pfizer) vaccine between 32–36 weeks gestation helps pass antibodies to the baby before birth
• For infants: Beyfortus (nirsevimab) or Clesrovimab (Enflonsia): long-acting monoclonal antibodies given as a single injection to protect infants under 8 months
• For older adults: RSV vaccines (Arexvy by GSK or Abrysvo by Pfizer) are recommended for all adults 75+ and adults 50–74 with underlying health conditions