Fever, usually at the beginning of the illness. A high fever does not mean the illness is more severe.
Babies may have additional symptoms, including:
A decreased interest in their surroundings.
Listlessness and sleepiness.
Fretfulness (irritability) and not sleeping well.
Apnea, where breathing stops for about 15 to 20 seconds. This usually occurs only in babies who were born prematurely and who also have a history of apnea.
It is hard to distinguish between a common cold and RSV infection. But unless you or your child has an increased risk of complications from RSV, it usually is not important to know which virus causes symptoms.