At no age are children immune to the effects of traumatic experiences. Even infants and toddlers can experience traumatic stress. The way that traumatic stress manifests will vary from child to child and will depend on the child’s age and developmental level.

Without treatment, repeated childhood exposure to traumatic events can affect the brain and nervous system and increase health-risk behaviors (e.g., smoking, eating disorders, substance use, and high-risk activities).

The Substance Abuse and Mental Health Services Administration's (SAMHSA) Trauma-Informed Approach offers similar helpful terms. SAMHSA refers to traumatic experiences and events, and the effects of these experiences and events, as "The Three E's of Trauma: Events, Experiences, and Effects"

Individual trauma results from an event, series of events, or set of circumstances that is experienced by an individual as physically or emotionally harmful or life threatening and that has lasting adverse effects on the individual's functioning and mental, physical, social, emotional, or spiritual well-being (SAMHSA, 2014, p. 7).

To enhance your understanding please read the following articles from the National Child Traumatic Stress Network:
Attached file:  What is Child Traumatic Stress (PDF)
Attached file:  Understanding Child Traumatic Stress, A Guide for Parents (PDF)