Can novel H1N1 Flu be transmitted by blood transfusion?

A Transfusion Medicine Physician in Denmark comments that in Denmark they are expecting the novel H1N1 influenza to gain momentum during late summer. He is concerned about the possible transmission of this virus through donated blood and wonders if at this point there is any evidence of transfusion-transmitted H1N1? According to the inquiring colleague, in Denmark they may choose to quarantine RBCs and FFP for 10 days in order to have donors call back in case they develop febrile disease after latest donation. Furthermore, they may introduce viral inactivation of platelet concentrates (there is an officially EU approved method available) since platelets cannot enter a 10 day quarantine period. The Denmark colleague asks if others can provide any scientific basis for the aforementioned strategies?

The following reply was submitted in response to the above:

1. The above query was referred to Dr. Louis M. Katz, Executive Vice President of Medical Affairs for the Mississippi Valley Regional Blood Center (attribution used with permission) who comments that he is not aware of any published evidence that transfusion transmission of influenza A has occurred. He adds: "We are now in the midst of the 3rd pandemic since transfusion has been a common medical practice and have lived through decades of seasonal influenza A, absent any such alleged transmission. Against this must be factored the passive nature of any surveillance for such an event (that is if it occurred would we have recognized it and attributed it to transfusion) and the fact that past may not be prologue for a new pandemic strain. There is evidence of brief viremia before the onset of symptoms (see Likos AM, et al: Influenza viremia and the potential for blood-borne transmission), and there is an ongoing attempt to study the current virus by evaluating donors who provide post donation information that suggests incubating H1N1 may have been present at the time of a fully acceptable donation. Those data should be available during the next 6 months. A study by the Retrovirus Epidemiology Donor Study (REDS) that used donor samples in a repository from communities with high prevalences of seasonal influenza will be presented in October at AABB. While I am not at liberty to provide details, the study found no evidence of viremia in their sample, although the power to detect low rates may not have been robust." Dr. Katz recommends to inquiring colleagues the August 2009 supplement to Transfusion (Special Issue: Emerging Infectious Disease Agents and their Potential Threat to Transfusion Safety), wherein the TTD committee has discussed 68 agents that hold some interest or potential as emerging transfusion transmitted diseases. They deal specifically with influenza viruses in two monographs starting on page 110S and the bibliography includes what is known about viremia. The bottom line is that donors with influenza A should be deferred until well, and that a deferral for a theoretical risk of transfusion transmission by asymptomatic viremic donors might have a severe adverse effect on the blood supply when it is compromised by a pandemic. At Dr. Katz's center, they will be recalling products from donors reporting influenza-like-illness in the 72 hours after donation. They will not be quarantining generally for any arbitrary duration, but given the very brief asymptomatic viremia described in the literature, 10 days seems excessive. Pathogen reduction for platelets is an attractive notion for many reasons much more compelling than for influenza A. Dr. Katz is not sure that the risk of this virus would justify a less than orderly implementation, but would be reluctant to discourage its use when validated and implemented in compliance with GMPs.

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