HSV is the herpes simplex virus, which may be contagious to others if both IgM and IgG are positive. If the IgM antibodies are negative and the IgG is positive it is usually not contagious to others. When the patient is positive for both IgG and IgM antibodies, it suggests that the patient is a contagious infection at this time, and may be contagious to others, usually after others come into contact with them. The source of herpes simplex virus infection is mainly patients infected in the acute phase and chronic carriers of the virus. Herpes simplex virus type 1 infections are mainly transmitted through direct contact and respiratory droplet transmission, while herpes simplex virus type 2 infections are mainly transmitted through sexual contact, or mother-to-child transmission through the birth canal. IgM and IgG are both immunoglobulins. After the virus infects the body, IgM antibodies appear earlier and disappear sooner after the end of the infection, which is a sign of recent infection. On the other hand, IgG antibodies appear later and are present in higher concentrations for a longer period of time after the end of the infection, suggesting that the patient has a previous or chronic infection and is generally not contagious. Patients with herpes simplex virus infection should follow the doctor’s instructions in order to avoid delays.