The Centers for Disease Control and Prevention is warning parents to monitor their children's symptoms if they become sick with what they think is a cold.
The CDC says it could actually be Respiratory Syncytial Virus, or RSV, a common respiratory virus.
Doctors in some parts of the country have noticed an increase in cases of RSV, which looks like the flu or cold, but can lead to bronchiolitis and pneumonia in children under age 1.
RSV produces symptoms like fever, reduced appetite, runny nose, cough and wheezing.
It is spread through coughing and sneezing or touching infected surfaces and then touching your eyes, nose or mouth.
The CDC recommends calling the doctor if your child is having difficulty breathing, not drinking enough fluids or experiencing worsening symptoms.
Health officials say it's best to wash your hands often, avoid touching your face with unwashed hands, cover your sneeze and cough, and stay home when sick.
CDC warns your child's cold symptoms could be sign of something more serious