SARS-CoV-2 Antibodies, Nucleocapsid is a specialized test that detects high-affinity antibodies specifically against the SARS-CoV-2 nucleocapsid protein, providing evidence of natural COVID-19 infection. This test is particularly valuable because it distinguishes between natural infection and vaccination, as currently available COVID-19 vaccines do not induce antibodies against the nucleocapsid protein. The test preferentially detects IgG antibodies, which typically develop 8-11 days after symptom onset and represent a more mature immune response. This distinction is crucial for evaluating patients with a history of COVID-19 vaccination who may have also experienced natural infection, and for diagnosing conditions like Multisystem Inflammatory Syndrome where determining the source of antibodies guides treatment decisions.