THURSDAY, April 23, 2026 (HealthDay News) -- For patients with early infection with Lyme disease (LD), standard and modified two-tiered testing (STTT and MTTT) diagnostic algorithms have low sensitivity, according to a study published online April 21 in the Journal of Clinical Microbiology.Elizabeth J. Horn, Ph.D., from the Lyme Disease Biobank in Portland, Oregon, and colleagues examined performance of STTT and MTTT algorithms using samples obtained from well-characterized patients with early LD. Performance of four U.S. Food and Drug Administration-cleared STTT or MTTT algorithms was compared using serum samples from 107 cases, 69 participants with a convalescent draw, and 144 endemic controls.The researchers found that algorithm sensitivity ranged from 22 to 36 percent at the initial blood draw, with specificity ranging from 98 to 100 percent. Higher sensitivity was seen for MTTT versus STTT algorithms. One STTT algorithm was less sensitive than the other, while sensitivity did not differ between the MTTT algorithms. Discordance was seen between the algorithms; of the 45 samples classified as laboratory-confirmed, only 22 were positive using all algorithms evaluated. Among cases with a suspected erythema migrans skin lesion, the likelihood of positive two-tiered serology increased with longer lesion duration and/or when presenting with one or more constitutional symptom."This study demonstrates that common two-tiered Lyme tests, utilized for decades, often fail to detect early Lyme disease and are leaving patients behind, highlighting a critical need for improved medical education on the limitations of current diagnostics," Horn said in a statement.Abstract/Full Text.Sign up for our weekly HealthDay newsletter