Usually, respiratory syncytial virus (RSV) causes mild, cold-like symptoms. However, in some babies, the symptoms can quickly get worse and can even become life-threatening. Severe RSV disease is more likely to develop in babies with the following risk factors:

• Premature birth. In infants born prematurely (ie, more than 4 weeks early), RSV can become a serious respiratory tract infection that requires hospitalization, especially early in life.
• Being born with lung disease. Babies younger than 2 years old born with chronic lung disease who have needed medical care for it within 6 months before RSV season are at high risk.¹
• Being born with heart disease. Babies younger than 2 years old born with serious heart disease may be at high risk.
• Low birth weight. Low birth weight (less than 5½ pounds) greatly increases the risk of death from RSV.¹
• Older brothers and sisters. Babies in contact with school-aged siblings can get RSV, particularly during the cold and flu season.^2-3
• Going to daycare. Babies who go to daycare are at higher risk for getting RSV.³ (Daycare is defined by the Centers for Disease Control and Prevention [CDC] as any setting outside the home where a child regularly spends ≥4 hours/week with ≥2 unreleated children.)⁴
• Family history of asthma. There is a higher risk for severe RSV in children with a family history of asthma.²
• Tobacco smoke and other air pollutants. You should never allow anyone to smoke around your baby. Tobacco smoke and other air pollutants can irritate your baby’s lungs and make it harder to fight RSV.²
• Multiple births. Multiple births (for example, twins) increase the risk for RSV because of low birth weight and an increased number of young siblings in the household.⁵

If your baby is at high risk for RSV disease, there may be additional protective steps you and your doctor can take. Learn more.