SAA is the abbreviation of serum amyloid A. SAA is an acute temporal protein produced by the liver, and when the body has acute inflammatory injury, the concentration of SAA will increase significantly, and within 4-6 hours the concentration will rise to more than 1000 times the normal value, whether it is viral infection, bacterial infection or protozoal infection, SAA will rise significantly within a short period of time, and when When the inflammation is controlled, the concentration of SAA will decrease rapidly, so SAA is one of the more sensitive indicators of human inflammation. SAA has a significant advantage over ultrasensitive C-reactive protein in the diagnosis of viruses, because the concentration of ultrasensitive C-reactive protein does not increase significantly during viral infection, but SAA can increase significantly. Therefore, compared with ultrasensitive C-reactive protein, SAA is more sensitive and accurate for diagnosing viral infections.