Novel coronavirus pneumonia has antibodies that may also be infectious and may be transmitted to others. New coronavirus pneumonia infection stimulates the body’s immune system to produce specific antibodies, the first to appear are IgM antibodies, suggesting an acute phase of infection. At this time, the virus is mostly positive for nucleic acid, so it is infectious, and IgG antibodies gradually appear later. If the IgG antibodies are quadruple elevated in two tests, it also indicates recent infection, and whether it is infectious depends mainly on whether the virus is positive for nucleic acid. If the virus is positive for nucleic acid, it is infectious. Whether or not a novel coronavirus pneumonia infection is infectious depends primarily on whether or not the nucleic acid test for the novel coronavirus is positive. Antibodies can be produced either by infection or by vaccination, and antibody testing is an auxiliary diagnostic method for the diagnosis of novel coronavirus pneumonia.