After receiving the first dose of vaccine, kittens will experience symptoms such as vomiting, diarrhea, lack of energy, and elevated body temperature. These are normal phenomena, and owners do not need to worry too much. They will usually get better in 2-3 days. Some cats may also have allergies, so it is best to observe the cat in the hospital for 15-30 minutes after giving the injection. If the cat appears abnormal, targeted treatment can be carried out in time.