What symptom might indicate a child is experiencing an acute illness?

Loss of appetite and lethargy are key symptoms that can indicate a child is experiencing an acute illness. These symptoms suggest that the body is responding to an illness, which often involves immune system activation. When a child is ill, they may lose interest in eating due to discomfort or a decreased sense of taste and smell, and lethargy can result from the body's energy being directed towards fighting off the illness rather than supporting regular activities.

In contrast, stable vital signs typically point towards a child being stable and possibly well, rather than acutely ill. Increased social engagement and improved mood and energy would generally indicate health and well-being, as a child who is feeling well is more likely to interact and play actively.