A lateral flow device (LFD) is a clinically validated swab antigen test that does not require a laboratory for processing and can turnaround rapid results within an hour at the location of the test.
Lateral flow tests (LFT) are validated technology, they are safe and the results are trusted. These tests have undergone rigorous testing and evaluation including at Public Health England’s research laboratories to ensure they are verified for use.
Lateral flow tests are highly specific, which means that only a very small proportion of people who do not have coronavirus will receive a positive result (false positive). Although they give a result much more quickly, LFT tests are not as sensitive as tests offered through other channels (e.g. PCR tests available in other channels like Local Testing Sites). Sensitivity measures how likely a test will return a positive result when that person is infected. This also means that if you test positive on a LFT test, it is likely that you are infectious at that moment, whereas people testing positive on more sensitive tests could be in the less infectious early or late stages of disease.
However, in mass testing, because so many people without symptoms are being tested there is still the possibility of getting a false positive result. Therefore, everyone who tests positive will need to have a confirmatory test to make sure the result is correct.