After the vaccination, blood tests are accurate. Most people do not have adverse reactions after the vaccine, as long as they do not have obvious signs of generalized fever, malaise, or other discomfort. The blood test is a good indicator of the state of the body after and before the vaccination, because the corresponding blood test will not change after the vaccination. However, if there are uncomfortable reactions after the vaccination, such as slight fever, fatigue, headache, and muscle aches, this is actually equivalent to a mild infection, and the blood count may be slightly elevated or otherwise changed. Therefore, this blood test will reflect not only the situation before the vaccination, but also the changes in the body after the vaccination. This blood test is still accurate, but because the vaccine affects some of the items in the blood test, it does not reflect the baseline status before the vaccine.