When is the best time to use the test for a reliable result? — TEST for COVID-19 SARS-CoV-2 - INTRANASAL

The test is designed for the early phase of a respiratory infection. Viral antigens of SARS-CoV-2 are most likely to be present in the nasal sample when symptoms have recently started and the viral load in the nose is higher. So the ideal window is within the first few days of noticing a sore throat, fever, runny nose, or fatigue. It is also commonly chosen after contact with someone who may be ill, or before visiting older relatives or returning to shared spaces.

If you test too early — for example, immediately after exposure, before the virus has had time to replicate — the result may be below the detection threshold. If you test too late, the viral load may have already dropped. In both cases, a negative result may not reflect your actual status. The test is qualitative, so it shows whether the target antigen is present above a threshold, not how much is there.

If your first result is negative but you still have symptoms or a high-risk exposure, the sensible approach is to repeat the test a day or two later, or to seek professional advice. The test helps with decision-making, but it does not replace a medical assessment when needed.