Rabies Antibody

Rabies passive protection is provided by rabies immune globulin (RIG), either human RIG (HRIG) or equine RIG (ERIG), which supplies immediate rabies‑neutralizing antibodies. Active immunization with rabies vaccine induces virus‑neutralizing antibodies that target the rabies virus glycoprotein (G). Post‑exposure treatment typically pairs RIG for immediate protection with vaccine doses to stimulate long‑term antibody production.

A rabies antibody test measures the level of antibodies against the rabies virus in a blood sample, typically using neutralization or immunoassay methods. It verifies whether vaccination or post‑exposure prophylaxis produced protective antibody levels and is used for occupational screening, travel requirements, or follow‑up. Results show antibody titers; clinicians interpret timing and adequacy to guide further vaccination or care. Testing is usually done 2–4 weeks after vaccination.

Anti-rabies vaccination (pre- or post-exposure) with rabies immunoglobulin when indicated is highly effective if given promptly and the full regimen is completed. It is not 100% guaranteed: delays, incomplete courses, lack of immunoglobulin for severe exposures, or weakened immunity can cause failures. Once clinical rabies appears, vaccines are ineffective and the disease is almost always fatal.

The IgG antibody for rabies is a virus‑specific immunoglobulin G that neutralizes rabies virus and indicates long‑term systemic immunity after vaccination or past infection. It targets viral glycoproteins, is measurable by virus‑neutralization assays (reported in IU/mL), and appears days to weeks after vaccination. A level ≥0.5 IU/mL is generally considered protective. Passive IgG (rabies immunoglobulin) gives immediate post‑exposure protection.

Rabies neutralizing antibodies typically become protective within 7 to 14 days after vaccination and often persist for years. Protective titres (≥0.5 IU/mL) are usually maintained for at least 1 to 3 years; many people keep adequate levels longer. People with continual or high-risk exposure should have antibody levels monitored and receive booster doses if titres fall below protective levels.

Check rabies immunity by a blood test (RFFIT or FAVN) that measures rabies virus neutralizing antibodies (RVNA) in IU/mL. Test 2–4 weeks after completing pre‑ or post‑exposure vaccination (or 1–2 weeks after a booster). A level ≥0.5 IU/mL is considered protective; if below, get a booster and retest. Arrange testing through occupational health or an accredited laboratory.