One line by C on a COVID-19 rapid antigen test indicates a negative result. This means that SARS-CoV-2 antigens, the proteins that indicate the presence of the virus, are not detected in your sample, or are present at very low levels. The C line (Control line) always appearing confirms the test worked correctly. The absence of a T line (Test line) signifies a negative result.
Understanding COVID-19 Test Results
- Positive Result: Two lines appear – one by C (Control) and one by T (Test). The intensity of the T line may vary; a faint line is still a positive result.
- Negative Result: One line appears – only by the C (Control). This shows the test functioned properly and no virus was detected.
- Invalid Result: No lines appear, or only the T line appears without the C line. This usually indicates a problem with the test itself and requires repeating the test with a new kit.
The control line (C) is a crucial part of the test. Its presence confirms the test has performed as expected. The test line (T) is where a positive result is indicated. Always refer to the specific instructions provided with your COVID-19 test kit.
Important Considerations:
- Test validity is time-sensitive; refer to your test's instructions for accurate result interpretation.
- Faint lines, either on C or T, do not invalidate the result as long as the line is visible.
- A negative result does not guarantee the absence of COVID-19, especially if symptoms persist. Further testing may be necessary.
