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This publication is available at https://www.gov.uk/government/publications/how-tests-and-testing-kits-for-coronavirus-covid-19-work/for-patients-the-public-and-professional-users-a-guide-to-covid-19-tests-and-testing-kits
How the tests work
Tests are only reliable if used in the way intended by the manufacturer. It is always important to follow the manufacturer’s instructions for use.
In order for a test to be safe to use, the company that develops this test must comply with the In Vitro Diagnostic Medical Devices Directive as implemented in the UK by Part IV of the Medical Devices Regulations 2002. Once they do, they are allowed to print a ‘CE’ mark on their test. This CE mark represents a declaration by the company that the test meets all of the legal criteria.
Tests will only be as reliable as the manufacturer claims if used in the way intended by the manufacturer. It is always important to follow the manufacturer’s instructions for use.
There are different stages to the testing process. A ‘CE’ mark is only valid if the following events happen in the way intended by the manufacturer:
- Collection of a sample (sometimes using a sampling kit)
- Testing of that sample
- Reading and interpretation of results; and
- The provision of the result is accompanied by information to help you understand what they mean
These stages are different for COVID-19 virus testing and COVID-19 antibody testing.
For a test used to detect the coronavirus that causes COVID-19, a sample is collected by the person having the test (self-administered) or by someone else (assisted) in a home or mobile environment such as police stations, care homes or drive-through centres. A sample is taken which usually involves taking a swab of the inside of your nose and the back of your throat, using a long cotton bud, or by providing saliva. The sample should be placed into special packaging provided and sent to the designated lab for analysis.
This type of sampling kit is currently being rolled out at scale by the government to key workers and those prioritised for testing. Those eligible can access sampling kits through the government’s official channels.
Read more about the testing process.
For tests to detect antibodies, and where this is intended by the manufacturer, a home blood sampling kit that has a valid CE mark can be sold to members of the public and used by them privately. Alternatively, a blood sample can be taken from a vein by a trained healthcare professional.
A self-test kit involves taking a lay person taking a sample, testing that sample and reading and interpreting the results by themselves. No COVID-19 self-test kits have received a CE mark and therefore there are no test kits in the UK suitable for home use.
It is currently illegal to supply test kits for use by members of the public in the UK though this may change if CE-marked self-test kits become available.
Members of the public should not purchase or use test kits.
Using the wrong type of test kit in the wrong setting can lead to inaccurate results, a false sense of protection or recovery and increased pressure on our NHS and social care systems. It is important to note that self-testing should not be confused with the use of a sampling kit at home, as mentioned above.
Laboratory and point-of-care testing
Once a sample has been collected, for all COVID-19 tests, testing of that sample is done by a healthcare professional. The testing process is not designed to be used by members of the public as the results need to be interpreted by trained and qualified healthcare professionals.
Some tests are undertaken in a laboratory by specialist staff using specialist equipment. Other tests require less equipment, are easier to use and can be performed by a fully trained and qualified healthcare professional – often in the presence of the person being tested. A healthcare professional will decide which test is best for an individual.
Types of COVID-19 tests
Tests for the virus
One type of test looks for the presence of genetic material from the COVID-19 virus within a swab or saliva sample. These tests are commonly referred to as polymerase chain reaction (PCR) tests. Antigen tests look for parts of the virus. The virus testing process is as follows:
- A sample is taken which usually involves taking a swab of the inside of your nose and the back of your throat, using a long cotton bud. In some cases, you may be asked to provide a provide a saliva sample
- That sample is either sent to a laboratory or processed nearby to check if coronavirus is present
- You will be informed of the outcome of the test
How it works
The testing process is performed by a fully trained, healthcare professional in a laboratory, ward or clinic. It involves analysing a sample collected from deep inside the nose or the back of the throat by a swab or the sample might be saliva or other fluid. The test can take from less than an hour to several days to get a result.
Tests for antibodies to the virus
This type of test looks for the presence of antibodies and can be used to see if you have been infected in the past.
These antibody tests are also referred to as serology tests and can be conducted in a laboratory or through point-of-care testing.
How it works
The test is intended to determine if someone has previously been infected with COVID-19 and now may have antibodies against the virus. The tests involve taking a blood sample, often a finger prick, which will be analysed for the presence of antibodies associated with COVID-19. Collecting the sample and performing these tests should only be performed and interpreted by fully trained, healthcare professionals and not by members of the public.
Some manufacturers are selling products intended to detect COVID-19 antibodies. These typically use a few blood drops applied to a small cassette. These tests should be available to healthcare professionals only.
The limits of testing kits
Even if a test has a CE mark, it will have limitations.
A test only provides results relevant to when the sample was taken. No test is 100% reliable.
The manufacturer will make a claim for reliability when used as intended, but many other factors can also affect reliability. A trained healthcare professional will understand all the limitations of the test.
It is not clear if being infected in the past means a person is immune and they cannot get infected with coronavirus again in the future.
It is also not clear whether it means a person can pass the virus onto others.
If you are unsure what a test result means, or what you should or should not do once you have received your test result, speak to your doctor or a medical professional.
COVID-19 antibody testing services made available to members of the public
Some UK providers such as high street pharmacies and private healthcare providers offer COVID-19 antibody testing for members of the public.
The test involves collecting a fingerprick blood sample into a small container following a set of instructions. The container is then sent to a laboratory for analysis and the results are returned direct to the person who took the test, with an indication of the reliability of the result.
The laboratory tests are CE marked and safe for use on blood drawn from the vein by a healthcare professional, but have not yet been validated by the manufacturer of the test to be used with a fingerprick blood sample. The sample collection kits have not yet been validated for home use and we can’t be sure that people collecting samples at home currently have sufficient support to collect samples in a way that the laboratory can process to give reliable results and therefore should only be used by a fully trained healthcare professional.
It’s very important for people at home to be able to understand the reliability of the result and what it means for them.
The science regarding immunity from COVID-19 is still emerging and the implications of a positive antibody result are as yet unknown.. A positive result may not mean a person is immune or if they have antibodies now, or how long this will last.
We strongly advise members of the public or organisations who have purchased these tests and received antibody results to continue to follow the Government’s advice whatever the result of the test.
What we’re doing
We are contacting providers of the antibody testing services and the laboratories running these tests.
We are asking them to temporarily stop offering these tests for sale until the regulatory and safety concerns have been resolved.
This involves further validation of the sample collection kits and the sample type and ensuring that result and supporting information is helpful and accurate.
How testing kits are regulated
The MHRA is the designated competent authority that administers and enforces the law on medical devices in the UK. It has a range of investigatory and enforcement powers to ensure their safety and quality.
An in vitro diagnostic medical device (IVD) includes tests performed on human samples (for example, blood, tissues, saliva, urine) for a medical purpose. As with all medical devices, manufacturers must place the CE mark on an IVD before it can be placed on the UK market.
CE marks are not issued by the MHRA. They are placed on the product by the manufacturer following registration with a competent authority such as the MHRA.
For some devices an independent certification body, called a Notified Body will also need to issue a certificate to the manufacturer before they can place a CE mark on their product. UK notified bodies are overseen by the MHRA.
The #FakeMeds campaign is a public health campaign which aims to reduce the harm caused by purchasing fake or unlicensed medical products online.
Learn how to spot a fake and purchase medical products safely online.
Any incidents involving medical devices, including testing kits, or suspected fake or unlicensed testing kits, can be reported via the Yellow Card scheme.