Respiratory syncytial virus (RSV) is usually mild like a cold for healthy older children and adults, but it can be dangerous and even life‑threatening for infants, older adults, and people with heart or lung disease or weak immune systems.

What RSV Is

RSV is a common respiratory virus that infects the nose, throat, and lungs and circulates seasonally, often in fall and winter.

Almost all children are infected at least once by age 2, and many adults are reinfected throughout life.

How Dangerous It Can Be

For most healthy people, RSV causes mild symptoms such as runny nose, cough, and low‑grade fever and clears on its own.
In high‑risk groups, RSV can cause severe lower respiratory tract infection (LRTI) like bronchiolitis and pneumonia, leading to low oxygen levels, respiratory failure, and sometimes death.

Who Is at Highest Risk

  • Infants, especially under 6 months
  • Premature babies or those with chronic lung or congenital heart disease
  • Adults 60–65+ years
  • Anyone with chronic heart or lung disease (asthma, COPD, heart failure)
  • People with weakened immune systems

In infants, RSV is the most common cause of bronchiolitis and pneumonia and a major cause of hospital admission for breathing problems worldwide.

In older adults, RSV can worsen asthma or COPD and is linked to higher risks of heart attack, stroke, and worsening heart failure around the time of infection.

Complications to Watch For

Severe RSV can lead to:

  • Bronchiolitis (swelling of small airways) and pneumonia
  • Low blood oxygen, breathing pauses (apnea) in young infants, and need for hospital or ICU care
  • Flares of asthma or COPD, and heart complications such as arrhythmias, heart attacks, and strokes in older adults and those with heart disease

Early RSV in infancy is also associated with recurrent wheeze and asthma later in childhood.

Prevention and When to Get Help

Vaccines for older adults and maternal vaccination, plus long‑acting antibody injections for infants, are now available in many places to reduce severe RSV disease.

Seek urgent care if someone with RSV has fast or difficult breathing, ribs pulling in with breaths, blue lips or face, trouble feeding, unusual sleepiness, chest pain, or confusion.

Information gathered from public forums or data available on the internet and portrayed here.