In chronic hepatitis B infection, what does the presence of IgM anti-HBc suggest?

The presence of IgM anti-HBc (immunoglobulin M antibodies against hepatitis B core antigen) suggests an active, acute or recent hepatitis B infection. In the context of chronic hepatitis B infection, this finding indicates that the virus is currently replicating, and the individual may have an active inflammatory process in the liver. The IgM anti-HBc typically appears shortly after infection and may remain detectable for several months, serving as a marker for the early immune response to the hepatitis B virus.

While the presence of other markers might indicate different stages or statuses of hepatitis B infection, the specific detection of IgM anti-HBc strongly correlates with acute or active hepatitis B rather than resolved infection, vaccination, or immunization status. Resolved infection is more likely associated with the presence of IgG anti-HBc and absence of IgM, while previous vaccination or immunization status would not result in the presence of IgM anti-HBc, since these responses relate to the core antigen rather than the surface antigen.