Question
Window period in HIV
Answer
The window period in HIV infection is the interval between actual infection and the time a given diagnostic test becomes capable of reliably detecting it — during this period, the individual is infected and potentially infectious, but standard testing may give a false-negative result.
Basis: viral markers appear in sequence — HIV RNA (earliest, ~7–10 days), then p24 antigen (~2–3 weeks), then HIV antibody (~3–12 weeks).
Significance: critically important for blood/organ donor screening; individuals tested soon after a suspected exposure should repeat testing after an appropriate interval.
Narrowing the window: 4th-generation combination antigen/antibody assays have shortened the window period to approximately 2–3 weeks, compared to ~3 months for older antibody-only assays.