Currently, no consensus has been reached on the optimal blood compartment to be used for surveillance of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) DNAemia. Although several comparative studies have been performed correlating CMV and EBV DNA loads in whole blood (WB) vs plasma, to our knowledge, no studies have ever analyzed the kinetics of both viruses in the two blood
compartments. In this retrospective non-interventional multicenter cohort study the kinetics of CMV and EBV DNA in 121 hematopoietic stem cell transplant recipients (HSCTR) have been investigated by analyzing in parallel 569 and 351 paired samples from 80 and 58 sequential episodes of CMV and EBV DNAemia, respectively. Unlike previous studies, a single automated molecular method, CE marked and FDA approved for use in quantifying CMV and EBV DNA in both plasma and WB was used. Furthermore, the complete viral replication kinetics of all episodes (including both the ascending and the descending phase of the active infection) was examined in each patient. The previously observed overall correlation between CMV DNA levels in WB and plasma was confirmed (Spearman's r = .85; P < .001). However, though WB and plasma CMV DNAemia reached peak simultaneously, in the ascending phase the median CMV DNA levels in plasma were about 1 log10 lower than WB. Furthermore, in patients who received pre-emptive therapy, CMV DNA showed a delayed decrease in plasma as compared to WB. A lower correlation between EBV DNA levels in plasma versus WB was shown (Spearman's r = .61; P < .001). EBV DNA kinetics was not consistent in the two blood compartments, mostly due to the lower positivity in plasma. Indeed, in 19% of episodes EBV DNA was negative at the time of EBV DNA peak in WB. Our results suggest a preferential use of WB for surveillance of CMV and EBV infection in HSCTR.