Alinity i Rubella IgG

The Alinity i Rubella IgG is a chemiluminescent microparticle immunoassay (CMIA) that quantitatively measures IgG antibodies to rubella virus in human serum and plasma samples on the Alinity i automated system. It is used to determine immune status to rubella in individuals, including women of child-bearing age, and has not been cleared for blood donor screening or use in cord blood, neonatal, immunocompromised, or immunosuppressed populations.

The subject device uses CMIA methodology with acridinium-labeled conjugate and paramagnetic microparticles, whereas the predicate (bioMérieux VIDAS RUB IgG) uses enzyme-linked fluorescent assay (ELFA) technology. The Alinity i assay includes 6 calibrators and 3 controls compared to the predicate's 1 calibrator and 2 controls, accepts both serum and plasma matrices (predicate serum only), and has a 30-day calibration storage window versus the predicate's 14 days.

Testing followed CLSI EP05-A3 (precision), CLSI EP17-A2 (detection limits), CLSI EP06 (linearity), CLSI EP07 and EP37 (interference testing), and CLSI EP12-A2 (clinical method comparison). Calibrators and controls are referenced to the WHO International Standard RUBI-1-94 for Anti-Rubella Immunoglobulin.

Although methodology differs (CMIA vs. ELFA), both assays share identical intended use, measure the same analyte using rubella virus antigen and anti-human IgG antibodies, produce equivalent result interpretations (nonreactive <5, equivocal 5–<10, reactive ≥10 IU/mL), and demonstrate substantial clinical concordance. CDC panel testing showed 93.9% positive percent agreement and 100% negative percent agreement; clinical agreement across multiple specimen categories (routine orders, pregnant females) ranged from 93–97.7% positive agreement and 77.8–100% negative agreement, establishing that the assay performs equivalently to FDA-cleared comparator methods despite different technological platforms.