Final answer:
The nurse should obtain information about allergic reactions to eggs before administering the MMR vaccine.
Step-by-step explanation:
Before administering the measles, mumps, and rubella (MMR) vaccine to a 15-month-old child, it is important for the nurse to obtain essential information regarding allergic reactions to eggs. The MMR vaccine is produced using cultured chicken cells, so individuals with a history of allergic reactions to eggs may have an increased risk of an adverse reaction to the vaccine. By obtaining this information, the nurse can ensure the safety and well-being of the child before administering the vaccine.