Pertussis, or whooping cough, is definitely classified as a contagious disease. According to the current infectious disease management laws in our country, pertussis is categorized under Class B infectious diseases. After understanding that it is a Class B infectious disease, we should also be aware of how infectious diseases are classified in our country. They are divided into Class A, Class B, and Class C based on the level of harm caused by the disease. Simply put, the more harmful, the less effective the treatment, and the higher the mortality rate, the more likely the disease will be classified as Class A, such as plague and cholera. On the other hand, diseases that are less harmful, such as influenza, rubella, and leprosy, are classified under Class C.