Anti-VCA EBV IgG antibodies have anamnestic character and persist in infected individual for a life. Seroconversion can be detected in early acute phase of the primary infection. Significant rise in IgG anti-VCA antibody indicate reinfection or reactivation. Avidity determination enables differentiation between primary and past infection or reactivation.

Anti-VCA EB IgM and IgA antibody response is typical for active infection. High levels of IgM anti-VCA are usually present in acute and convalescent phase of infectious mononucleosis (IM), while in EBV reactivation IgM response is low and often undetectable and IgA response is more pronounced. After recovery, both IgM and IgA may persist for several weeks or months.