One concern is that those who receive a negative result from LFTs may still have the virus – experts have previously said this means the tests should be seen as offering a “red light” rather than a “green light”.īut as the prevalence of Covid falls, the problem of false positives also becomes pressing. However, according to the Department of Health and Social Care (DHSC), and comparing results against those obtained by PCR testing, the false positive rate for LFTs is fewer than one in 1,000, while the false negative rate could be as high as 50%. When it comes to LFTs, the accuracy appears to depend on the make of the test used, whether people have symptoms, and who is conducting the test.įor example, one study by researchers at the University of Oxford and Public Health England’s Porton Down lab found the LFTs were more accurate in the hands of skilled scientists, picking up 79% of Covid cases, than self-trained members of the public, who detected 58% of Covid cases.Įstimates for these rates vary. There are two important measures to think about when it comes to accuracy: false positives, where a test erroneously suggests someone has Covid, and false negatives, where the test fails to pick up that someone has the virus. The idea is that the tests will help pick up cases of Covid that may otherwise go undetected, for example because of few or no symptoms, and help prevent the spread of the virus. However, earlier this month the government announced that LFTs would be made available for all adults to take a test twice a week. Until recently the tests were used for mass testing in particular settings, such as schools. However, LFTs have the advantages of being cheap and offering results in about 30 minutes, and they can be carried out at home.

These tests differ from polymerase chain reaction (PCR) tests, which look for genetic material from the virus, called RNA (ribonucleic acid) and are more accurate. It works a little like a pregnancy test, but instead of looking for certain hormones, the test contains antibodies that bind to coronavirus proteins. Should coronavirus proteins be detected, a red line will appear, in addition to a second line that indicates the test is working. The fluid is then drawn into the device and along a strip of test paper. A swab is taken from the back of the nose or throat, mixed with an extraction fluid, and a drop of this mixture is placed in a well on a small device.

LFTs are a rapid way of testing for Covid-19.

Covid rapid test accuracy rate