Sudden infection of hepatitis B is mainly related to the characteristics of the disease and the lack of protective measures. 1. Characteristics of the disease: hepatitis B has the characteristic of insidious onset, and there are no obvious symptoms in the body after the disease, the patient’s body has been infected with hepatitis B for a period of time, but due to the symptoms brought about by hepatitis B are not obvious, the patient does not notice or does not know that he suffers from hepatitis B, and he feels particularly surprised only after the diagnosis of hepatitis B is made. 2. Failure to take protective measures: Hepatitis B is a contagious disease, which is caused by the infection of hepatitis B virus, and is mainly transmitted through broken skin and mucous membranes, sexual contact, blood, mother and child, etc. Patients who do not take proper protective measures in their normal life will not have the chance to get infected. Patients who do not take proper protective measures in their normal life and who have not been vaccinated against hepatitis B are prone to increase the chances of hepatitis B infection. If you find yourself suddenly infected with hepatitis B, you should go to a regular hospital in time.