Clinical Application of Variation in Replication Kinetics During Episodes of Post-transplant Cytomegalovirus Infections

•CMV doubling time was longer than previously reported, and not influenced by type of transplantation or prior CMV immunity.•In cohorts with comparable CMV doubling time, intervals between screening with CMV PCR may be extended from 7 to 10 days.

BackgroundCytomegalovirus (CMV) infection in transplant recipients is reported to replicate with a doubling time of 1.2–2 days, and weekly screening is recommended for early diagnosis. We re-evaluated these features in our cohort of transplant recipients.MethodsThe CMV doubling time of the first CMV infection in the first year post-transplant could be calculated for 193 recipients of haematopoietic stem cell or solid organ transplantation. Factors determining the proportion of recipients with a high diagnostic CMV viral load (≥ 18,200 IU/mL) were explored using mathematical simulation.FindingsThe overall median doubling time was 4.3 days (IQR 2.5–7.8) and was not influenced by prior CMV immunity, or type of transplantation (p > 0.4). Assuming a fixed doubling time of 1.3 days and screening intervals of 7 or 10 days, 11.1% and 33.3% were projected to have a high CMV viral load at diagnosis, compared to 1.4% and 4.3% if the doubling time varies as observed in our cohort. Consistently, 1.9% of recipients screened weekly had a high diagnostic virus load.InterpretationScreening intervals can be extended to 10 days in cohorts with comparable CMV doubling time, whereas shorter than 7 days is required in cohorts with shorter doubling times to maintain pre-emptive screening quality.