Is it possible that a person is classified as long-term on the assay but was infected recently in the last 6-12 months (i.e. after a recent negative test result)?

Yes. As pointed out earlier, individuals can transition from recent to LT status at varying time periods (3 to >9 months) after infection. This means some individuals who transition early but are still within 12 months of infection will classify as LT. The assay is designed to identify individuals who are still in “recency” status with weak antibodies but cannot identify those who may have transitioned to LT status. However, this individual-level misclassification is less consequential for recent infection surveillance, which uses RTRI to help detect trends in recent infections at the population-level.