Final answer:
The priority nursing intervention for a child with Reye's syndrome is monitoring vital signs and neurological status.
Step-by-step explanation:
The priority nursing intervention for a child with Reye's syndrome is monitoring vital signs and neurological status. Reye's syndrome is a serious condition that affects the liver and brain, so it is crucial to closely monitor the child's vital signs, such as heart rate, blood pressure, and breathing, as well as their neurological status, including level of consciousness and responsiveness. By doing so, the nurse can detect any changes or complications early on and take appropriate action.