Health protection is a measure taken for diseases that have a clear cause, or for diseases that have specific means of prevention. Health protection plays a major role in preventing and eliminating the causes of diseases. (1) Specific prevention against the cause of disease Specific protection measures against the cause of disease play a decisive role in the prevention of disease. According to the epidemic monitoring of infectious diseases or the analysis of the immunity level of the population, planned vaccination can make the body develop specific immunity and interrupt the spread of infectious diseases. In China, the five vaccines (BCG, hepatitis B, polio, diphtheria and hepatitis B) are administered to children to provide mandatory immunization against seven infectious diseases, including measles, tuberculosis, polio, pertussis, diphtheria, tetanus and hepatitis B. It should be said that the rapid decline in the incidence of infectious diseases worldwide over the past half century has been largely due to the first level of disease prevention, especially the utility of immunization. For certain chemical element endemic diseases whose etiology has been clarified, such diseases can be prevented and treated by artificially supplementing or reducing the supply of certain elements. For example, endemic goiter can be prevented by taking iodized salt, and dental caries can be prevented by increasing the fluoride content in drinking water. For occupational diseases such as silica deposition, the occurrence of the diseases can be reduced by improving the process and removing harmful substances. (2) Focused prevention of special populations On the basis of comprehensive preventive health care for the whole population, attention should be paid to the importance of high-risk populations, high-risk environments and high-risk reactions in disease prevention. High-risk groups are special groups of people who are vulnerable to certain diseases caused by disease-causing factors. For example, people with disabilities are vulnerable to injury during important life events; people who smoke and have high blood cholesterol are vulnerable to coronary heart disease; people with family history of cancer or precancerous lesions are vulnerable to cancer, etc. Noise, environmental pollution, and major disasters are known as high-risk environments, which often induce certain occupational diseases, endemic diseases, and physical and mental diseases, etc. Overreaction of the body to various stimuli can cause high-risk reactions, such as tachycardia and hypertension in people who are mentally stressed. Preventive health care for the elderly, women and children is an important part of the prevention of high-risk groups. Preventive health care for the elderly focuses on the impact of physical, psychological and social factors on the health of the elderly, delaying the onset of aging, loneliness and death, avoiding or reducing impairments in consciousness, memory, language and behavior, and improving the quality of life of the elderly. Maternal and child health care is to strengthen the protection of adolescence, pre-marriage, pregnancy and delivery, lactation and menopause, to regulate reproduction and fertility, and to ensure the safety of mother and child. Preventive health care for children and adolescents is to explore the influence of genetic and educational life environment on children and adolescents according to the developmental rules of children and adolescents, and to lay the foundation for improving the quality of their lives in adulthood and old age. Primary prevention is often carried out using a two-way strategy, which combines universal prevention for the entire population and focused prevention for high-risk groups, both of which complement each other and improve efficiency. The former, called population-wide strategy, aims to reduce the exposure level of the whole population to disease risk factors and is achieved through health promotion; the latter, called high-risk strategy, aims to eliminate the specific exposure of the population to certain disease risk factors and is achieved through health protection.