BLOOD TRANSFUSION: VIRAL COMPLICATIONS
BLOOD TRANSFUSION: VIRAL COMPLICATIONS — what can still be transmitted?
Modern blood screening has made transfusion-transmitted viral infection extremely uncommon, but the risk is not zero.
The major viruses historically associated with transfusion include:
HBV → HCV → HIVOther transfusion-associated viruses include HTLV-I/II, depending on geographic region and screening policy.
Why can transmission still occur?Donated blood undergoes extensive donor screening and laboratory testing, including nucleic-acid testing (NAT) in many systems.
The major residual problem is the:
WINDOW PERIOD
A donor may have recently acquired an infection while viral markers remain below the detection threshold.
Modern NAT has dramatically shortened this window.
Important distinction: CMVCytomegalovirus (CMV) behaves differently because it is predominantly leukocyte-associated.
Risk can be markedly reduced by:
Leukoreduced blood components ± CMV-seronegative components when specifically indicated by local transfusion policy.
This is particularly relevant in selected high-risk recipients.
What about hepatitis A or E?HAV is only rarely transmitted through transfusion because viremia is usually brief.
HEV is increasingly recognized as a potential transfusion-transmitted infection in some regions and is particularly important in immunocompromised recipients.
Postgraduate PearlFor exams, remember:
Transfusion viral risk = HBV + HCV + HIV
But modern blood safety relies on:
DONOR SELECTION → SEROLOGY → NAT → LEUKOREDUCTION where appropriate
And remember:
Leukoreduction ≠ elimination of HBV/HCV/HIV risk.
It is particularly useful for reducing leukocyte-associated complications, including CMV transmission risk.
Take-home messageBlood transfusion is now extremely safe from a viral-transmission perspective—but “screened” does not mean absolutely zero risk.
Residual risk is primarily related to very early infection/window-period donations and other uncommon or emerging pathogens.
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