A subset of infected individuals who are infected with the pathogen and do not show any symptoms are called asymptomatic infected individuals. This type of infection is difficult to detect because it is not accompanied by any specific symptoms in the early stages of infection. A professional blood and saliva test is required to determine whether the person is infected and the specific type of bacteria or virus. Some of those with asymptomatic infections remain asymptomatic, while others develop various discomforts over time, such as cough, fever, sore throat, difficulty breathing, localized pain, swelling, pus, itching at the infected area, or generalized pain, weakness, and gastrointestinal discomfort. This is when the asymptomatic infected person has transformed into a patient. Asymptomatic infected persons are not easily detected, are more insidious, and may inadvertently transmit the virus or bacteria to people in close contact with them, requiring special vigilance to avoid spreading the epidemic and causing adverse effects on society. Therefore, for bacterial or viral infections that are highly contagious and have clearly defined detection processes, such as novel coronaviruses, patients who are self-conscious of a possible infection should immediately report it to the community and the sentinel hospital, even if they do not have overt symptoms such as cough, fever or malaise, while paying attention to protection. For other diseases, patients who feel unwell or are suspected to have infection should seek medical attention for differential diagnosis and take early treatment.