Possible False Positive with Syphilis Test

FDA is alerting clinical laboratory staff and health care providers that false reactivity or false positive Rapid Plasma Reagin (RPR) test results are possible when using Bio-Rad Laboratories’ BioPlex 2200 Syphilis Total & RPR kit. A false positive can occur in some people who received a Covid-19 vaccine, an FDA alert says. “Based on information provided by the manufacturer, Bio-Rad Laboratories, RPR false reactivity was observed in some individuals for at least five months following a Covid-19 vaccination,” it says.

The agency says that more research is underway to determine the extent of the issue, and 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,” it adds.