Question
The child received both the flu vaccine and the B-type flu vaccine at once, and one arm is red and swollen with a hard lump.
Answer
If the child has developed redness and hardness in the area following vaccination, it could be due to local soft tissue reaction caused by the vaccine or due to fluid accumulation. Cold compresses and massage can be appropriately applied to help alleviate these symptoms. If you are still not reassured, it is recommended to consult with a doctor if necessary.