Children and adolescents are particularly affected by the COVID-19 pandemic and the official containment measures. However, the effects on their mental health have been little studied. The aim of this narrative review is to summarize existing evidence on the mental health of children and adolescents in the first weeks of the COVID-19 pandemic and during the measures taken to contain it in Germany. First international and national studies draw a differential picture. Children and adolescents showed symptoms of anxiety and depression as well as a reduced quality of life. The closure of childcare and educational facilities and the associated loss of the familiar daytime structure as well as loss of contact and independent learning at home posed considerable challenges for affected children and their families. Spatial confinement at home and the lack of alternative options of stay during the containment measures could also have lead to increased family stress, heightened family aggression, and domestic violence. However, the findings of several studies also show that many families coped with the time during the containment measures mostly well. In the event of possible future pandemics or further waves of the COVID-19 pandemic, the needs of adolescents and their families during the containment measures should be given greater consideration.