The U.S. Food and Drug Administration (FDA) is alerting clinical laboratory staff and healthcare providers that false reactivity, or "false-positive", Rapid Plasma Reagin (RPR; non-treponemal) test results, when using the Bio-Rad Laboratories BioPlex 2200 Syphilis Total & RPR kit can occur in some people who received a COVID-19 vaccine.
The information was provided by the manufacturer, Bio-Rad Laboratorie. RPR false reactivity was observed in some individuals for at least five months following a COVID-19 vaccination.
More research is underway to determine the extent of the issue. It is not known if other RPR tests may be affected similarly. Treponemal testing for syphilis such as Treponema pallidum particle agglutination (TP-PA) and treponemal immunoassays do not appear to be impacted by this issue.
Healthcare providers should make patients who received a reactive RPR result using the Bio-Rad BioPlex 2200 Syphilis Total & RPR test kit aware that they may need to be retested for syphilis with another test to confirm results.
COVID-19 vaccines do not cause syphilis.
The FDA recommends clinical laboratory staff and healthcare providers who use the Bio-Rad BioPlex 2200 Syphilis Total & RPR kit should perform confirmatory testing for all reactive results. Use of only one type of serologic test (non-treponemal or treponemal) for people without an earlier syphilis diagnosis is insufficient for diagnosis.
The FDA will continue to work with Bio-Rad Laboratories.