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The Death of the Western Blot: Modified Two-Tier Testing
In 2026, the labor-intensive "Western Blot" confirmatory test is being rapidly phased out in favor of the Modified Two-Tier Testing (MTTT) algorithm.
The New Standard: MTTT replaces the second-tier Western Blot with a second, more sensitive ELISA (Enzyme-Linked Immunosorbent Assay). This shift has increased the sensitivity in early-stage Lyme from roughly 50% to over 75% without sacrificing specificity.
Reimbursement Shift: Major payers, including Premera (effective February 2026), have updated their medical policies to prioritize MTTT, acknowledging that second-tier ELISAs capture early antibody responses that the Western Blot often misses.
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