COVID-19 has come back with a vengeance. With the increase in the number of "two positive" cases, some people are beginning to worry that multiple infections will cause the virus to accumulate in the body, causing symptoms to accumulate. There are even rumors that people can be infected up to eight times, and any more will be fatal. The latest scientific gossip list has been released, refuting the above claims. In addition, there are more health rumors that have been "targeted" this time. The monthly "Science" rumor list is guided by the Beijing Association for Science and Technology, the Beijing Municipal Committee's Cyberspace Office, and the Capital Internet Association, and jointly released by the Beijing Association of Science and Technology Journalists and Editors, as well as the Beijing regional website's anti rumor platform. Rumor has it that blood testing can lower the body's immune system. It is rumored that blood testing can remove immune functioning white blood cells, as well as important substances such as electrolytes and vitamins that are important to the body. Even mistakenly believing that the more seriously ill a person is, the more blood tests they take, which leads to many people being bedridden and even dying prematurely. Actually, drawing blood does not harm the body. The general blood volume for a blood test does not exceed 20 milliliters, while the human body has an average of 4000 milliliters of blood and has the function of automatic regeneration. Drawing a small amount of blood does not have any impact on human health. Although the main cells that make up the human immune system are white blood cells, the proportion of red blood cells in the blood is relatively large, while white blood cells are relatively small. Generally, donating 200-400 milliliters of blood will result in a loss of 1-2% of the total number of white blood cells in the human body, and within 1-2 hours after blood sampling, the lost white blood cells will return to their original number. Therefore, after drawing blood, it will not lose many white blood cells and will not cause a decrease in human immunity. Rumor has it that asthma patients will "wheezing". Is it true that without wheezing symptoms, asthma is not necessarily asthma? For asthma, many people still focus on the symptoms of "shortness of breath and difficulty breathing" in movies and TV dramas. In fact, these are only typical manifestations of acute asthma attacks. When patients encounter stimuli such as cold and dry air, they are prone to asthma attacks. The typical symptoms of asthma are recurrent wheezing, which can be accompanied by shortness of breath, chest tightness, or coughing. However, there are still many atypical asthma cases in clinical practice. Cough variant asthma, with cough being its only or main clinical manifestation; Chest tightness variant asthma, with chest tightness as the sole or main symptom; Concealed asthma, without typical symptoms of recurrent wheezing, shortness of breath, chest tightness, or coughing, but with prolonged elevated airway responsiveness. Rumor has it that drinking lemon water can lead to stones. There are many causes of stones, including genetics, metabolism, anatomical structure, and diet, among which diet is the most concerned. From the perspective of composition, the stones in the body are mainly calcium oxalate, and the large amount of oxalic acid in the diet to some extent intensifies the formation of stones. Vegetables such as spinach, celery, and leeks have high levels of oxalic acid, but this does not include lemons. Unlike oxalic acid, which forms insoluble substances when it encounters calcium, the rich citric acid in lemon combines with calcium to form calcium citrate tetrahydrate, which can be slightly soluble in water. At the same time, the slightly acidic nature of citric acid in the intestine can also promote the absorption of various mineral elements such as calcium, iron, and zinc, which is beneficial for health. Rumor has it that the "upside down water control method" can save drowning victims. The truth is that a "classic" image of rescuing a drowning person is circulating online - the rescuer lifts the drowning person and their feet fall down