Worry is an invisible force that may adversely affect population’s health and well-being. Empirical evidence on how threats are perceived (either by parents or their primary school-aged children) during abnormal events of health crises remains limited. To gain an insight into the impact of COVID-19 on children, an anonymised online survey of parents (n=332) and their primary school-aged children across five Australian states during the early virus outbreak is conducted. Factors contributing to heightened children’s worry about (1) contracting the virus or (2) playing outdoors during lockdowns or social distancing amid health crises are examined. During the COVID-19 outbreak, 30% of children were “very worried” about contracting the virus, and 25% were “very worried” about playing outdoors. Parents' age, history of distress symptoms, and the amount of daily exposure to pandemic news, primarily by parents, were associated with children worrying. Ethnic background modified children’s worry about playing outdoors. However, variables contributing to children’s worry showed geographical variation aligning with the geography of morbidity levels. The home environment is fundamental to children's well-being. During abnormal events, parents are urged to limit children’s exposure to unfiltered news and care for the children’s and parent’s mental health. Listening to children's voices, timely intervention, better access to health care, and identifying areas with vulnerable children are crucial.