Overview of RSV (Respiratory Syncytial Virus)

Respiratory Syncytial Virus (RSV) is a common respiratory virus that primarily affects the nose, throat, and lungs. Nearly every child is infected by the age of two, and reinfections can occur throughout life. While RSV often causes mild cold-like symptoms, it is the leading cause of bronchiolitis and pneumonia in infants and a major cause of hospitalization among older adults and individuals with chronic medical conditions.

Key Facts About RSV

• Pathogen: RSV is an enveloped RNA virus with two main subtypes, A and B, that circulate each season.
• Disease Burden: It is one of the most common causes of hospitalization in infants in the United States. In adults aged 60 and older especially those with heart or lung disease RSV can lead to significant illness and even death.
• Immunity: Infection does not produce lifelong immunity. Reinfections are common throughout life but tend to be milder as the immune system develops partial protection.

Transmission, Incubation, and Seasonality

How RSV Spreads

RSV spreads easily from person to person through:

• Respiratory droplets from coughing or sneezing
• Direct contact, such as kissing a child’s face or touching contaminated hands
• Fomites (surfaces) — the virus can survive for several hours on hard surfaces like toys, crib rails, and doorknobs

Incubation and Contagious Period

• Incubation Period: 4–6 days (range: 2–8 days)
• Contagious Period: Typically 3–8 days, but infants and immunocompromised individuals can remain contagious for longer periods

Seasonality

In North America, RSV activity typically peaks in the winter months, though timing can vary by region. In some areas, RSV outbreaks may start as early as late fall and last through early spring.

Who Is at Higher Risk for Severe RSV

While RSV can affect anyone, certain groups face a higher risk of severe complications:

Infants

• Under 6 months of age
• Born prematurely (<29 weeks gestation)
• With chronic lung disease, congenital heart disease, or neuromuscular disorders
• With airway abnormalities or difficulty clearing secretions

Older Children and Adults

• With asthma, COPD, cystic fibrosis, or chronic heart disease
• With weakened immune systems (e.g., due to chemotherapy, HIV, or medications)

Other High-Risk Groups

• Older adults (especially those aged 60+)
• Pregnant individuals
• Residents of long-term care facilities or crowded housing environments

Symptoms of RSV

The symptoms of RSV can vary depending on age and underlying health.

In Infants and Toddlers

• Nasal congestion, runny nose, and persistent cough
• Poor feeding or difficulty nursing
• Wheezing, rapid or labored breathing, chest retractions
• Apnea (pauses in breathing), especially in very young infants
• Dehydration (fewer wet diapers, dry mouth, or lethargy)

In Older Children and Teens

• Cold-like symptoms (runny nose, cough, mild fever)
• May trigger asthma attacks in susceptible individuals

In Adults

• Mild upper respiratory symptoms in healthy adults
• In older adults or those with chronic conditions, RSV can cause severe bronchitis, pneumonia, or worsening of underlying diseases

Potential Complications

RSV can lead to several complications, especially in high-risk individuals:

• Dehydration or poor feeding in infants
• Respiratory failure requiring oxygen therapy or mechanical ventilation
• Secondary bacterial infections, such as ear infections or pneumonia
• Exacerbation of chronic lung or heart disease
• Long-term effects: Children with severe RSV infections may have a higher risk of recurrent wheezing or asthma later in life

Diagnosis of RSV

Most mild RSV infections are diagnosed clinically based on symptoms and physical examination. Testing is generally recommended for:

• Severe or hospitalized patients
• Immunocompromised individuals
• Cases where a confirmed diagnosis could influence treatment or infection control measures

Diagnostic Tests

• Rapid Antigen Detection Test (RADT): Provides quick results but is less sensitive in adults.
• Polymerase Chain Reaction (PCR/NAAT): The gold standard for RSV diagnosis, offering high accuracy.
• Chest X-ray: Performed only if pneumonia or severe respiratory distress is suspected.