Read condition-specific symptoms and clinical context for Respiratory syncytial virus. A common respiratory virus that is mild for most but serious for infants and older adults.
WHO describes RSV as an RNA virus that infects cells along the human respiratory tract from the nose to the lungs, causing anything from a mild cold to life-threatening lower respiratory infection. Infants, especially those under six months, are at highest risk of severe disease and death, and RSV also causes severe illness in older adults and people with underlying conditions.
CDC states people usually show symptoms within 4 to 6 days of infection and that symptoms appear in stages rather than all at once. Most RSV infections go away on their own in a week or two.
Possible symptoms: Runny nose; Congestion; Coughing; Sneezing; Fever; Wheezing; Decrease in appetite.
CDC states that in very young infants the only symptoms may be irritability, decreased activity and breathing difficulties, and advises calling a healthcare professional for difficulty breathing, not drinking enough fluids or worsening symptoms. Antiviral medication is not routinely recommended.
Source check: 2026-09-19. Educational content; independent scientific review remains pending.