Chronic False Positive Rapid Plasma Reagin (RPR) Tests Induced by COVID-19 Vaccination

Abstract

False positive reactive plasmin reagin (RPR) reactivity following a COVID-19 vaccine has been reported, and it is therefore conceivable that individuals who receive frequent coronavirus disease 2019 (COVID-19) vaccinations may exhibit durable RPR responses. Here, we sought to investigate the extent to which repeated mRNA COVID-19 vaccines can elicit chronic false RPR reactivity in a longitudinal cohort. Participants (n = 119) in an IRB-approved (#20201026), longitudinal SARS-CoV-2 cohort study were screened for RPR reactivity via manual RPR card assays. Samples with reactive results underwent additional testing, including follow-on RPR screening at additional timepoints, confirmatory fluorescent treponemal antibody (FTA-ABS) testing and anti-nuclear antibody (ANA) testing. Medical histories were collected. We observed (n = 2) screen-positive RPR results (1.7% [2/119]) following booster vaccination, for which two individuals exhibited chronic, vaccine-induced RPR reactivity for up to 9 months following booster vaccination. Both participants were ANA-negative. It is imperative for clinicians to be mindful of the potential immunologic interference of COVID-19 vaccines with standard infectious disease assays, including RPR testing. Detailed medical histories and clinical contexts, including recent vaccination, should be reviewed prior to proceeding with distressing and invasive workups.

Keywords

• COVID-19
• RPR
• ID assay