TT-CMV Observational Birth Cohort Study (TT-CMV)

The spread of viruses through transfusions is the cause of serious illness and death in recipients whose immune systems are unable to fight infection. Another group of patients whose immune systems are underdeveloped and can be affected by a particular virus known as cytomegalovirus (CMV) is low birthweight infants (LBWIs). CMV can be spread through the placenta, during the birth process, through breast milk, while in the hospital or while caring for someone carrying the virus as well as through a transfusion, known as transfusion-transmitted (TT-CMV).

The spread of TT-CMV in LBWIs can be curtailed by transfusing blood products that are CMV negative as well as to filter the white cells in blood that carry the virus (leukoreduction). The purpose of this study is to see if the use of these two strategies can lower the spread of CMV through a transfusion. How "safe" the blood actually is through leukoreduction is not known and CMV still occurs in LBWIs. It is not clear whether this approach is optimal or whether additional safety steps are needed to completely prevent TT-CMV. Specific actions that could tell us when virus has reached the blood product or breast milk is to test each of these to determine if virus slipped "unnoticed" and/or when the product was not thoroughly filtered.

In this study, the investigators believe that the use of both prevention strategies will result in a lower rate of TT-CMV, and that the "cause" of TT-CMV may be found in the presence of CMV at the DNA level or by unfiltered white cells that remain in the blood product. Thus, the most significant clinical question that remains to be addressed is whether this double strategy for transfusion safety actually provides a "zero CMV-risk" blood supply or whether further safety measures (DNA testing + 100% leukoreduction) must be used to protect this extremely vulnerable patient group from CMV infection. This birth cohort study will be done with 6 participating NICUs, and will study both CMV positive and negative mothers in order to estimate the rate and pathway of CMV transmission to the LBWI who receives a transfusion. Another study goal is to compare or link any CMV infection by either transfused units where the virus was undetected, or filter failure. If CMV disease occurs, the investigators will be able to describe the course and outcome in LBWIs who develop TT-CMV.