There are 2 main types of test currently being used to detect if someone has COVID-19:
- Polymerase Chain Reaction (PCR) tests
- Lateral Flow Device antigen (LFD) tests
PCR tests detect the RNA (ribonucleic acid), the genetic material of a virus. PCR tests are the most reliable COVID-19 tests. It takes some time to get the results because they are usually processed in a laboratory. If you have symptoms of COVID-19, you should arrange to have a PCR test.
LFD tests detect proteins in the coronavirus and work in a similar way to a pregnancy test. They are simple and quick to use. LFD tests are not as accurate as PCR tests in all circumstances but can detect a similar number of people with high levels of coronavirus as PCR tests. They are mainly used for people who do not have symptoms of COVID-19. LFD tests are being used to regularly test staff working in care homes, the NHS and schools, as well as in community programmes offering rapid tests to people without symptoms, known as ‘asymptomatic testing programmes’.
If you have COVID-19 symptoms or have received a positive COVID-19 test result
Stay at home and self-isolate.
If you develop symptoms of COVID-19, stay at home and self-isolate immediately. If you have a positive test result but do not have symptoms, stay at home and self-isolate as soon as you receive the results. Your household needs to isolate too.
If you have symptoms of COVID-19, arrange to have a PCR test if you have not already had one. Stay at home while you are waiting for a home self-sampling kit, a test site appointment or a test result. You can leave your home in a few specific circumstances, but do not go to work, school, or public areas and do not use public transport or taxis.
If you are notified by NHS Test and Trace of a positive test result you must complete your full isolation period. Your isolation period starts immediately from when your symptoms started, or, if you do not have any symptoms, from when your test was taken. Your isolation period includes the day your symptoms started (or the day your test was taken if you do not have symptoms), and the next 10 full days. This means that if, for example, your symptoms started at any time on the 15th of the month (or if you did not have symptoms but your first positive COVID-19 test was taken on the 15th), your isolation period ends at 23:59 hrs on the 25th.
You can return to your normal routine and stop self-isolating after 10 full days if your symptoms have gone, or if the only symptoms you have are a cough or anosmia, which can last for several weeks. If you still have a high temperature after 10 days or are otherwise unwell, stay at home and seek medical advice.
If you have a negative COVID-19 PCR test result after being tested because you had symptoms
If your PCR test result is negative but you still have symptoms, you may have another virus such as a cold or flu. You should stay at home until you feel well. Seek medical attention if you are concerned about your symptoms.
You can stop isolating as long as:
- you are well
- no-one else in your household has symptoms or has tested positive for COVID-19
- you have not been advised to self-isolate by NHS Test and Trace
Anyone in your household who is isolating because of your symptoms can also stop isolating.
Testing after your isolation period has ended
If you have tested positive by PCR for COVID-19, you will probably have developed some immunity to the disease. However, it cannot be guaranteed that everyone will develop immunity, or how long it will last. It is possible for PCR tests to remain positive for sometime after COVID-19 infection.
Anyone who has previously received a positive COVID-19 PCR test result should not be re-tested within 90 days of that test, unless they develop any new symptoms of COVID-19.
If, however, you do have an LFD antigen test within 90 days of a previous positive COVID-19 PCR test, for example as part of a workplace or community testing programme, and the result of this test is positive, you and your household should self-isolate and follow the steps in this guidance again.
If it is more than 90 days since you tested positive by PCR for COVID-19, and you have new symptoms of COVID-19, or a positive LFD antigen or PCR test, follow the steps in this guidance again.