A rapid antigen test for COVID-19 is a quick lateral‑flow immunoassay that detects viral proteins from a nasal or throat swab. It gives results in about 15–30 minutes and is useful for identifying active, contagious infections. It’s less sensitive than PCR, so a negative result doesn’t fully exclude infection—confirm by PCR if symptoms persist or exposure risk is high. Often used at home.

Wash hands and check kit expiry and instructions. Collect sample per kit: tilt head, insert swab into each nostril and rotate as instructed, then place swab in the provided extraction buffer and mix. Squeeze the required drops into the test well, wait the stated time (usually 15–30 minutes), and read the result within the specified window. If positive, isolate; if symptomatic but negative, retest or seek PCR.

Rapid antigen tests detect viral proteins when viral load is high. They usually become positive around symptom onset and are most sensitive in the first week of symptoms, often 1–3 days after symptoms begin and roughly 3–7 days after exposure. If asymptomatic after exposure, test at about day 5–7 or test immediately and repeat after 48 hours. A negative early test does not reliably rule out infection.

A rapid antigen test result shows whether viral proteins (antigens) were detected, indicating a likely current infection. Results are quick (usually 15–30 minutes). A positive result suggests active infection—self-isolate and seek medical advice or confirmatory PCR if required. A negative result reduces the likelihood but isn’t definitive, especially with symptoms or recent exposure; repeat testing or PCR may be needed per local guidance.

A positive antigen test means the test detected viral proteins, indicating an active infection and a likely period of contagiousness. It’s most reliable in early, symptomatic stages but can miss low viral loads. Follow public-health guidance: isolate, inform close contacts, and get a confirmatory PCR if required by local rules. Seek medical advice for worsening symptoms or if you are high risk.

Rapid antigen tests detect viral proteins and are most accurate when viral load is high, typically early in symptoms. Sensitivity varies (roughly 50–80% versus PCR), while specificity is high (about 97–99%). A negative result doesn't fully exclude infection, especially in asymptomatic or early/late stages; repeat or confirm with PCR if clinical suspicion is strong. Serial testing improves detection.