Respiratory Synctial Virus

Respiratory Syncytial Virus (RSV) is a common virus that typically causes mild, cold-like symptoms during fall through spring. However, RSV can lead to more severe illnesses, such as bronchiolitis (inflammation of the small airways) and pneumonia, especially in infants under 6 months of age and older adults. Infants under 1 year old are particularly at risk for severe disease and hospitalization.

To protect infants from severe RSV, the CDC recommends two immunization options:

1. Maternal RSV Vaccine (Pfizer’s Abrysvo): Administered between 32 and 36 weeks of pregnancy. The antibodies passed from the mother help protect the baby for approximately 6 months after birth.
2. RSV Antibody (Nirsevimab): Given directly to infants, providing immediate protection for at least 5 months. It is highly effective in preventing RSV-related hospitalizations.

Who Should Receive Nirsevimab?

• Infants younger than 8 months who are entering their first RSV season (fall through spring) should receive Nirsevimab if:
  • The mother did not receive the RSV vaccine during pregnancy.
  • The mother’s RSV vaccination status is unknown.
  • The infant was born within 14 days of the mother’s RSV vaccination.
• Children aged 8 through 19 months who are at high risk for severe RSV and entering their second RSV season are also recommended to receive Nirsevimab. High-risk children include those with:
  • Chronic lung disease of prematurity who required medical support (e.g., corticosteroids, diuretics, or oxygen) within the past 6 months.
  • Severe immunocompromise.
  • Cystic fibrosis with severe lung disease or poor growth.
  • American Indian or Alaska Native children.

Timing and Administration:

• Nirsevimab is most effective when administered just before RSV season begins (October–November) or, ideally, during the baby’s birth hospitalization.
• A single dose provides protection throughout the first RSV season (typically from October through March).

Side Effects:

• The side effects of Nirsevimab are generally mild, such as pain, redness, or swelling at the injection site. Severe reactions are rare.