How does NAT affect window period risk in donor screening?

• A. NAT has no effect on window period
• B. NAT replaces serology entirely
• C. NAT reduces window period risk by detecting viral nucleic acids
• D. NAT increases window period risk

Answer: (C)

Nucleic acid testing detects viral genomes directly, so infections can be identified earlier than with antibody-based tests. After infection, there’s a window period before antibodies develop and serology may be negative even though the donor is infectious. NAT detects the virus’s genetic material (RNA or DNA) during this window, reducing window period risk by catching infections before serology turns positive. It’s used in addition to serology to further lower residual risk, not as a complete replacement. NAT does not increase the window period, and while it improves safety, a small residual risk can remain due to test sensitivity and the range of viruses included in the panel.