Anti-SARS-CoV-2 Nucleocapsid Protein Antibody, Serum/Plasma (Qualitative Immunoassay)

What This Test Measures

The nucleocapsid protein is a structural component of the SARS-CoV-2 virus. After infection, your immune system may produce antibodies against it. This test detects these antibodies in your blood, indicating whether your body has recognized and responded to the virus. Antibodies against the nucleocapsid protein are typically detected around 1–3 weeks after infection and can persist for months or years.

Why It’s Done

Doctors may order this test to confirm a past COVID-19 infection if you’ve had symptoms or exposure but test negative for the virus itself. It can also help assess immune response in vaccinated individuals or those recovering from infection. Unlike antigen tests, which detect the virus itself, this test looks for evidence of your immune system’s reaction.

When to Expect Results

Results may take several days to a week to process, depending on lab workflows. Follow-up with your healthcare provider for interpretation, especially if you have ongoing concerns about infection status or immune response.

What to Expect Before the Test

No special preparation is needed. You’ll typically provide a blood sample via venipuncture, similar to other blood tests. If you’re on blood-thinning medication, inform your healthcare provider beforehand.