A combined HIV antigen and antibody screen reported against a signal cutoff.
This is the p24 antigen part of a combined HIV test, reported as a Signal-to-Cutoff (S/Co) index. p24 is a protein from the core of the HIV virus that appears in the blood very early after infection, often before antibodies can be measured.
The S/Co value compares the signal from your sample against the test's cutoff line. A value below 1.0 is non-reactive, and a value at or above 1.0 is reactive.
The p24 antigen helps catch HIV earlier than antibody testing alone, narrowing the window between exposure and a detectable result. This matters because early infection is when the virus level is high and treatment is most valuable.
A non-reactive S/Co is reassuring for the period the test covers. A reactive S/Co points to possible early infection and must be confirmed with further testing before any diagnosis.
Aniva reads your result against research-backed ranges, not just the lab's wide normal. The reference shown below is specific to this biomarker.
This component is reported as a Signal-to-Cutoff (S/Co) index.
| S/Co value | Interpretation |
|---|---|
| Less than 1.0 | Non-reactive (negative) |
| 1.0 or above | Reactive, needs confirmation |
The cutoff is defined by the assay and may vary by laboratory. A reactive result is not a diagnosis on its own.
You see where your p24 signal sits relative to the cutoff. An S/Co below 1.0 is non-reactive. An S/Co at or above 1.0 is reactive and needs confirmatory testing. The number itself is not a viral load and is not a diagnosis.
p24 antigen can fall as antibodies rise later in infection, so a single value reflects one moment in time. Very recent exposure can still be missed. Rare false-reactive results are possible, which is why confirmation is required. Fasting and time of day do not affect the result.
Read with the HIV antibody result from the same combo test and with confirmatory testing if the screen is reactive.
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