DNase analysed by a novel competitive assay in patients with complications after ChAdOx1 nCoV-19 vaccination and in normal unvaccinated blood donors.

Increased levels of neutrophil extracellular traps (NETs) have been detected in individuals with vaccine complications after the ChAdOx1 nCov vaccine with a correlation between the severity of vaccine side effects and the level of NETosis. DNases may disrupt NETs by degrading their content of DNA, and a balance has been reported between NETs and DNases. Because of this and since the inflammatory marker NETs may be used as a confirmatory test in diagnosing VITT, it is of interest to monitor levels of DNase in patients with increased NETs levels. The current novel rapid DNase ELISA was tested in blood samples of patients with known increased levels of NETs with or without VITT after ChAdOx1 nCoV-19 vaccination. DNase levels in VITT patients were significantly increased compared with normal unvaccinated blood donors and compared with patients with post-vaccination symptoms but not VITT. However, since EDTA was found to inhibit DNase, serum and not EDTA-plasma samples should be applied for DNase testing. The novel DNase assay may serve as a supplementary test to the NETs test when analysing samples from patients with suspected increased NETs levels.