Guidance

For patients, the public and professional users: a guide to COVID-19 tests and testing kits

Updated 8 August 2023

Types of test

Virus test

These tests, sometimes called swab or antigen tests, check to see if you are currently infected with the virus.

The swab sample is taken from your nose and throat.

Alternatively, a saliva sample might be used.

This sample is then tested to see if you have the virus.

Lateral flow antigen test or rapid antigen test

Lateral flow antigen tests are rapid turnaround virus tests that can process COVID-19 samples on site, without the need for laboratory equipment. Most produces easy-to-understand results in under half an hour. Because of this, they can be performed in a laboratory or a point of care setting.

Public Health England (PHE) and the University of Oxford have recently carried out extensive clinical evaluation studies on lateral flow tests.

In the UK, the MHRA has granted NHS Test & Trace an exceptional use authorisation to use certain lateral flow devices as self-tests to show infection in people who don’t have symptoms. For more information, please see the section about self-testing.

Antibody tests

These tests check for antibodies to see if you have had an infection with the virus in the past. This test requires a blood sample.

This sample is then tested to see if you have had the virus in the past.

Antibody tests are currently only offered to NHS and care staff, as well as some hospital patients and care home residents. They can also be bought privately, but it’s important to be aware of their limitations.

These tests are not used for diagnosis but rather to give us a better understanding of the prevalence of the virus in different places.

Sample collection kits

A sample collection kit is the name given to the different parts of a COVID-19 test that help obtain a sample. This kit must have a valid CE, CE UKNI or UKCA mark to show that the manufacturer has met the minimum safety and performance requirements for the product.

The sample you have to provide, and whether or not you can collect that sample yourself, will depend on what type of test you have.

Please note that not all sample types have been proven to be effective in COVID-19 testing.

Virus test samples

This type of test usually involves collecting a swab sample from the nose, the mouth, and/or throat. A swab is a small piece of soft, absorbent material on a plastic stick.

Some virus tests use saliva samples, collected into a small container, to check for the virus, but this type of sampling is not done routinely in the UK.

You may collect swab and saliva samples at home yourself (this can also be referred to as ‘self-sampling’), or you can get a healthcare professional to do it. The sample is then sent to a laboratory to check for genetic material from the virus.

Swab self-sampling kits are rolled out by the government. For more information, please read the NHS Coronavirus testing page.

If you are using a virus self-test, for example a lateral flow antigen self-test, you would not send the sample to a laboratory because the test can generate the results for you. For more information, please see the section about self-testing.

Antibody test samples

This type of test uses a blood sample, which can be collected in several ways.

Some antibody test kits require a venous, from the vein, blood sample, which can only be collected by a healthcare professional or a qualified person.

Other antibody test kits use a small amount of blood. This type of sample is taken from a capillary via a finger prick blood sample. In certain cases, you may be required to then put this sample on special paper to dry – this is known as a dried blood spot (DBS). When only a small amount of blood is needed, you may collect the blood sample at home yourself, or you can get a healthcare professional to do it.

Both capillary and venous blood samples are sent to a laboratory to check for antibodies.

Concerns about the use of sample collection kits

Anyone using a sample collection kit to test for COVID-19 must read the instruction leaflet carefully. It is very important that you have a clear understanding of the process because if the sample is not collected properly, the result may not be accurate.

If you have any concerns with the sample collection kit or any of its parts, please contact the kit provider for advice. If there are any components missing, the provider should be able to send you a replacement to ensure you are able to use the kit safely.

If something in the kit is difficult to use or breaks when you use it, please report the problem immediately on our Coronavirus Yellow Card website.

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 healthcare professional.

Self-testing

A self-test kit is one in which you take a sample, test it yourself, and then read and interpret the results yourself as well. This is different from self-sampling. In that case, you take a sample at home and then you send it to a laboratory for testing.

Lateral flow antigen self-tests

In the UK, the MHRA has granted NHS Test & Trace an exceptional use authorisation to use certain lateral flow devices as self-tests to detect infection in people who do not have any COVID-19 symptoms and who may not otherwise have been tested.

This means that the tests can be used by anyone without previous experience of testing, in their own home or another community setting such as a place of work.

If you get a positive result from these self-tests, it is extremely likely that you are currently infected with COVID-19 and you risk infecting others. It is very important that you follow the information in the instructions leaflet that came with the kit. You must report your result to the NHS using one of the methods detailed in the instructions for use. When you report your result, you will be told what to do next.

If you get a negative result from these self-tests, it may mean that you are infectious, but the test has not been able to detect it. If you test negative, you must continue to follow national and local rules and guidelines including regular handwashing, social distancing and wearing face coverings, where required.

These tests can only be distributed by the NHS Test and Trace programme, from a government authorised process. To make sure that you perform the test correctly and get an accurate result, you must read and follow the manufacturer’s instructions for use that came with the testing kit. You should only take the self-test if you are sure that you understand the instructions. If you don’t follow the manufacturer’s instructions, the test might not work properly, and the results will not be valid.

Concerns about the use of ethylene oxide in sterilising test swabs

The MHRA is aware of concerns about the safety of using ethylene oxide (EO) to sterilise the swabs used in coronavirus testing kits (including lateral flow tests).

Ethylene oxide is a gas that is commonly used to sterilise many different types of medical devices, including swabs used in test kits.

The sterilisation process consists of a number of highly controlled and monitored stages, including removing ethylene oxide after treating the swabs. The amount of residual EO that is allowed has been set (by the international standard ISO 10993-7:2008) according to contact time of the medical device with the person. Contact time is divided into 3 categories: limited, prolonged, and permanent duration.

The swabs used in lateral flow test kits fall under the category of limited contact time. These limits are not further divided by body weight and therefore the limits set are also applicable for children.

These allowable limits were selected to ensure that any residual levels present on the medical device after sterilisation pose minimal risk.

The average time of contact for a single test (around 20 seconds) and the current testing regime (twice a week), means that each person is exposed to any residue on the swab for around 40 seconds per week. Calculating from the allowed residues, a person would need to be tested twice a week for over 40 years for the total contact time to be in a higher contact category. Therefore, the manufacturer’s original calculations that these swabs are in the ‘limited’ contact category are still valid for the current testing regime.

In the highly unlikely event that a swab does contain a residual amount above the allowable limit, the risk to the user is still considered to be very low.

As part of the sterilisation process the manufacturer must confirm, and document, that the residual EO level on a medical device is below the specified allowable limit before the device is packaged ready for use. The whole process is overseen by an independent third-party organisations before a CE/CE UKNI/UKCA mark can be placed on the medical device. The identifying number of the third party can be found next to the CE/UKCA mark symbol on the packaging of the swab.

Limitations of COVID-19 tests

There isn’t a test that is 100% reliable, even those who meet regulatory standards for performance and safety. The results are also only valid for that specific sample at that point in time.

If you are unsure what a test result means, or what you should or should not do when you received your test result, you should first contact the test provider and if you remain unsure then speak to your GP or a healthcare professional.

It’s important to understand the limitations of COVID-19 tests, because an incorrect or misinterpreted result can lead to a false sense of reassurance. For example, if you are infected with the virus but the test you use shows a false negative result (it says you do not have the virus even though you do), you may unknowingly spread the virus to other people or not seek the treatment you may need.

Antibody testing has limitations because there is still a lot that we don’t know about immunity to COVID-19. For example, we don’t yet know if:

• antibodies protect you from getting COVID-19 in the future
• antibodies stop you from passing the virus on to others
• having a negative antibody test means you have never been infected

You can find the reliability, sometimes referred to as sensitivity, of the test on the label or in the instructions of the testing kit.

COVID-19 testing services

Virus tests are available from the NHS Test and Trace programme. Some UK employers, occupational health and other private healthcare providers also may offer tests.

More information on private testing and private providers is also available if you click on the links. For private testing, click here. For private providers, click here.

Antibody tests are currently only offered to NHS and care staff, as well as some hospital patients and care home residents. These can also be bought privately. It’s important to know that the General Pharmaceutical Council have advised pharmacies not to offer rapid antibody testing.

Testing for international travel

Those who want to travel abroad or return to the UK from abroad are no longer required to take a coronavirus test.

Click here for information about ‘fit-to-fly’ tests and Test to Release.

PCR tests and/or lateral flow antigen self-tests may be offered by testing providers for this purpose.

The MHRA is aware that non-compliant lateral flow antigen tests might be offered by some of the providers. If a lateral flow antigen test is marketed for self-testing, but does not have a 4-digit identifier number next to the CE, CE UKNI or UKCA mark symbol on the packaging, it is not compliant with the regulations required for self-testing. It may be a test manufactured for professional use only.

The MHRA has issued guidance explaining that professional use tests should not be used by members of the public even if they are supervised via a video link.

Before buying a self-test, everyone should consider the information about the test offered by the testing service provider:

• Is there a CE, CE UKNI or UKCA mark and a 4-digit identifier number for the Approved Body on the packaging?
• Are the instructions provided on how to take the test clear?

Ask for further information about the test from the provider if you are unsure.

If you suspect a professional use test is being sold or has been sold to you for self-testing, you can report this via the Coronavirus Yellow card reporting site – click here to read the section about reporting it below.

How COVID-19 testing is regulated

Sample collection kits and the COVID-19 tests are medical devices. For a medical device to be safe to use, it must have a valid CE, CE UKNI or UKCA mark. These marks are a declaration by the manufacturer that the test meets the required standards of safety and performance.

These regulatory requirements aim to ensure that the products do not compromise the safety of patients and users and are designed and manufactured to achieve the performance specified by the manufacturer for the stated purpose.

CE, CE UKNI and UKCA marks are not issued by the MHRA. They are placed on the product by the manufacturer. Before the product can sold in the UK the manufacturer or their UK Responsible Person (UKRP) must register it with the MHRA. Click here to read about registering a medical product on the market.

An Approved or Notified Body have to approve self-tests so they can receive the CE/CE UKNI/UKCA marking, or the MHRA must grant an Exceptional Use Authorisation. This is indicated by a CE, CE UKNI or UKCA mark and a 4-digit identifier number next to the CE mark symbol on the packaging. Click here for a list of tests which have been granted an Exceptional Use Authorisation.

There are a number of lateral flow antigen self-tests which have now received CE certification from an EU notified body.

The MHRA administers and enforces the law on medical devices in the UK and has a range of investigatory and enforcement powers to ensure the safety and performance of medical devices in the UK.

For more information, please click here to read our guidance on how In Vitro medical devices such as these are regulated.

Reporting problems with COVID-19 tests using the Yellow Card scheme

If you have any problems with COVID-19 testing products, you should report them as soon as you can. This can help us to identify any potential issues with the kits. Details on what and how to report are outlined below.

Patients - what to report

Examples of problems to report include, but are not limited to:

• taking more than one test and getting different results
• the test being invalid (for example, the control line did not appear)
• finding the instructions for use or the labelling difficult to understand
• the kit (or part of it) breaking
• the buffer liquid leaking
• not being able to take a sample for any reason
• having difficulty using the software app (for example, you cannot report the result)
• getting injured during the self-testing process (example of injuries include allergic reactions, cuts and bruises)
• if you have concerns that a professional use test has been sold as a self-test

Professional users - what to report

Examples of problems to report include, but are not limited to:

• false positive or negative results
• the test being invalid (for example, the control line did not appear)
• inadequate quality control or calibration
• being unable to get a reading
• failing to obtain a sample (for example, problems during swabbing or collecting a fingerprick blood sample)
• any component not performing as intended
• inadequate, confusing or misleading labelling
• incorrect packaging
• contamination issues
• the kit (or part of it) breaking
• the buffer liquid leaking
• having difficulty using the software app or any concerns over its safety

How to report

If you have any problems while using a COVID-19 testing product (test or sample collection kit) please report via it the Coronavirus Yellow Card website.

You can also contact the kit provider for advice or to replace any missing components.

When reporting via Yellow Card, please include the following information, if applicable, on each individual adverse incident report.

Information related to your device (usually can usually be found in the product packaging)

• Type of device (PCR test, antibody test, antigen test or sampling collection device)
• name of manufacturer
• name of device
• product code (this can be a serial number, lot number and/or barcode)
• brand

Information regarding the incident

• Description of failure/problem
• Symptoms of patient, including any resultant injury
• Patient and/or carer’s immediate actions (for example, any immediate treatment)
• Healthcare worker’s immediate actions (for example, any immediate treatment)
• Date of incident
• Name of place of purchase (for example healthcare facility, manufacturer or government)
• Any other relevant information

There’s a different way to report a problem with a medical device if you’re in Wales, Scotland or Northern Ireland.

For more information on COVID-19 software and apps, see our advice for members of the public and professional users: software and apps used in COVID-19 pandemic.