TOPLINE:

The study demonstrated a substantial clinical burden from multiple viral infections in recipients of allogeneic hematopoietic cell transplants — especially among patients with cytomegalovirus (CMV) seropositivity, haploidentical donors, or acute graft-vs-host disease or those receiving T‑cell depletion therapy.

METHODOLOGY:

• Researchers conducted a retrospective study to evaluate the incidence, risk factors, and clinical outcomes of multiple viral infections in the first year following an allogeneic hematopoietic cell transplant.
• They enrolled 430 patients (median age, 52 years; 62% male) who underwent their first allogeneic hematopoietic cell transplant; patients were followed up for 12 months posttransplant or until death, whichever occurred first.
• Data were collected for 13 viruses, including CMV, Epstein-Barr virus (EBV), BK polyomavirus (BKV), varicella-zoster virus, human herpesvirus 6 (HHV-6), human rhinovirus/enterovirus (HRV/ENT), and other respiratory viruses.
• Viral infection was defined as the detection of any virus by polymerase chain reaction within 12 months of a transplant, and concurrent infection was defined as the simultaneous detection of two or more viruses.

TAKEAWAY:

• Overall, 744 viral infections were observed within the first year of transplant, mostly comprising CMV infection (55%), followed by EBV (51%), BKV (21%), HRV/ENT (18%), and HHV-6 (5%) infections.
• At least one viral infection was detected in 85% of recipients; 57% had two or more viral infections, including 18% with three and 6% with four viral infections.
• Risk factors associated with increased multiple viral infections were receipt of stem cells from a haploidentical donor (hazard ratio [HR], 1.56); CMV seropositivity in the donor (HR, 2.25), the recipient (HR, 2.59), or both (HR, 2.72); use of T-cell depletion therapy (HR, 1.44); and presence of severe acute graft-vs-host disease (HR, 1.44; P < .01 for all).
• Patients with more distinct viral infections developed their first infection sooner (median time to first infection, 18, 25, and 40 days for three or more viral infections, two viral infections, and one viral infection, respectively) and had longer hospital stays within a year posttransplant (53, 40, and 37 days, respectively; P < .001 for both).

IN PRACTICE:

“We found that CMV seropositivity in either the donor or recipient can increase the risk of multiple viral infections, suggesting that past infection with CMV likely increases one’s vulnerability to other viral infections,” the authors of the study wrote.

“Nevertheless, the viral dynamics between these viruses remain unclear, appealing for a stricter monitoring of CMV and intervention in allogeneic transplantation patients not only with EBV and BKV infections but also concurrently with other viruses,” they added.

SOURCE:

The study was led by Kar Yee Yong, Department of Infectious Diseases, Peter MacCallum Cancer Centre, Melbourne, Australia. It was published online on September 29, 2025, in Open Forum Infectious Diseases.

LIMITATIONS:

As this was a retrospective study, inherent issues with missing or incomplete data existed. CMV and EBV infections were routinely monitored; however, other viral infections were tested only when clinically indicated, potentially underestimating their true incidence. Additionally, information on specific antiviral treatments, which would have been important for understanding hospital admissions, was not collected.

DISCLOSURES:

One author reported receiving a fellowship grant through the National Health and Medical Research Council and consulting fees from MSD, Gilead Sciences, and Takeda, paid to her institute.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.