Can blood tests distinguish between bacterial or viral infections? The answer is no. There are many questions that people around the world struggle with, both at home and abroad, such as how to accurately distinguish between a viral and bacterial infection in a patient with a cough and fever. Some long-standing, classic medical textbooks, such as the Oxford Handbook of Clinical and Laboratory Investigation, 2nd edition, published in 2005, state that “white blood cells are often elevated in infections, for example neutrophils are elevated in bacterial infections and lymphocytes are elevated in viral infections (but not always). The key is this interesting phrase in parentheses. 10 years ago, when I was younger and more aggressive, I often wondered how to grasp “not always”. That is, sometimes this is not reliable? But there wasn’t much discussion about it, so I decided to ignore the words at that time. But in reality, the pain continues, and it is indeed “not always so”. Peripheral blood white blood cell (WBC) counts and neutrophil percentages were previously thought to be the traditional screening tools for determining whether a child had a bacterial infection, but recent studies have confirmed that WBC counts and neutrophil percentages alone are neither sensitive nor specific as screening tools for bacterial or viral infections, and in layman’s terms are unreliable. Therefore, they cannot be used alone to predict bacterial or viral infections in children and need to be combined with clinical history and other laboratory tests. In addition, C-reactive protein (CRP) tests are not routinely performed in children with even mild cases of common pneumonia; children who require hospitalization or have pneumonia-related complications should have CRP tests, which can be combined with clinical assessment of response to treatment. Erythrocyte sedimentation rate (ESR), CRP, or serum calcitoninogen (PCT) concentrations also cannot be used alone or in combination to differentiate bacterial or viral pneumonia; the sensitivity and specificity of using these nonspecific inflammatory markers to differentiate between bacterial and nonbacterial pathogens is low, and it is difficult to derive a fractional marker. In layman’s terms, this paragraph means that the use of “ESR, CRP or PCT concentrations to accurately differentiate between viral and bacterial infections is also unreliable. The above has been generally accepted by foreign physicians, and therefore foreign physicians rarely request routine blood and CRP tests to distinguish between viral and bacterial infections; however, the vast majority of Chinese physicians deal with this issue in a vastly different way. But why are the differences so great at home and abroad? First of all, medical education and learning in China always makes people feel sorry that the education on the understanding of routine blood is not up to date, and the understanding of ESR, CRP or PCT concentration is too simple and stereotyped. Medical teachers do not teach their students well. The reason for this is that, in terms of the changing spectrum of diseases in various countries, China has been repressed for too long in the shadow of bacterial infections of infectious diseases, and so this energy to fight with bacteria to the death has been inherited. There is a proverb that when you always think you are a hammer, you see nails everywhere. Similarly, when Chinese doctors feel like they are antibiotics, they open their eyes and reflexively see bacteria in their pupils, and the struggle to get rid of them is the main reason why routine blood tests have become mandatory and why antibiotics are misused. However, the problem is that the types of diseases in China have actually changed and non-bacterial infections, immune disorders, metabolic disorders and other diseases have become mainstream. The vast majority of respiratory infections are viral in origin. In terms of probability, even a non-medical student can say that 100 febrile patients with their eyes closed that they have a viral infection with no less than 90% accuracy, not to mention blood tests. On the contrary, foreign medical philosophy is relatively more reasonable with the times, medical education standards are unified, almost all non-bacterial diseases anyway, blood routine is not checked. Secondly, the majority of Chinese doctors pursue the halo of famous doctors, and patients are intoxicated by the miraculous effect of immediate results, coupled with a relatively poor medical system. In such an environment, doctors and patients are generally anxious, the connection between doctors and patients is not loyal, there is not enough follow-up time, and the arrangement of follow-up visits between doctors and patients always depends on luck. So at the first consultation, doctors are eager to pull the net to check all over and make a group of miracle doctors; patients are eager to find out the cause of the disease instantly and recover instantly, creating a legend. With the loss of patient and planned medical observation, routine blood and CRP naturally become the main characters. Finally, the pressure on doctors at home and abroad is also worlds apart. Doctors abroad have a well-established overall medical service system and are relatively unafraid of risk. As long as it is beneficial to most people, they can choose to delay waiting for accurate determination of the pathogen and wait for accurate indicators to appear. Domestic doctors, in the face of the individual difficult to resolve the contradictory pressure, in order to avoid the risk of a few, under the guidance of a limited concept, choose to collectively check, take medication. Finally, a few more points: 1, China’s doctors moral standards are higher than the social average, some of the tricks to earn black money is not reflected in the vast majority of Chinese doctors. 2, as the author of this article, I am also a product of domestic medical education, the knowledge of blood routine, the difference between bacteria and viruses is also a stumbling, but and I have a desire to keep pace with the heart of many people, we are willing to grow together with patients, please give us a harmonious space, time. 3. There are still some ways to accurately identify bacteria and viruses, but they are time-consuming and labor-intensive, and most of the time, they are still difficult to understand. 4, despite the inability to accurately distinguish between viruses and bacteria, the other medical significance of routine blood and CRP is still significant.