Guidance

COVID-19: summary guidance for service providers on point of care tests for diagnosis and management

Updated 11 January 2022

This guidance was withdrawn on 1 April 2022

This guidance has been superseded by Antibody testing for SARS-CoV-2: extended information.

Applies to England

This guidance is being reviewed in line with the removal of self-isolation regulations on 24 February 2022.

1. General points on testing

The UK Health Security Agency (UKHSA) does not accredit or advise on individual coronavirus (COVID-19) point of care testing devices or platforms, but has contributed to and led Department of Health and Social Care (DHSC) commissioned evaluations of specific devices and published relevant findings.

There are a different types of test for COVID-19. They are not interchangeable, and care should be taken with terminology.

The results of COVID-19 tests that detect different parts of the virus or immune response provide different clinical information that often overlaps:

• nucleic acid tests, such as polymerase chain reaction (PCR) tests, indicate whether there is viral RNA present in the tested specimen. The majority of those with positive PCR results are infectious but the RNA of the virus can persist in some individuals for many weeks and therefore a repeat PCR test is not recommended within 90 days in someone whose symptoms have resolved
• coronavirus virus protein antigen tests such as lateral flow devices for antigens (LFD Ag) indicate whether a person has the virus now and is likely to be infectious to others
• tests for coronavirus antibodies (antibodies produced by the patient in response to the infection) are performed on blood sent to a laboratory or by dropping a fingerprick blood specimen into an LFD test for antibodies (LFD Ab)

A point of care (POC) test provides a result near to the person being tested, instead of sending their specimen to a laboratory. A POC test may be used within a healthcare setting, or in other settings such as a residential care home, a school, or in a person’s home. Generally, results from POC testing are much more rapid than traditional laboratory testing.

Broadly speaking, there are three types of POC testing that mirror the other types of testing:

• POC tests that detect viral genomic material through amplification. These tests are similar in sensitivity to laboratory-based reverse transcription polymerase chain reaction (PCR) tests
• POC tests which detect viral protein, such as LFD Ag tests. These are less sensitive compared to a PCR test for detecting virus at a lower viral load, such as at the start of an infection, but are very good at detecting infectious virus later in the infective episode.
• POC tests that detect antibodies against the coronavirus (LFD Ab)

The UK Medicines and Healthcare products Regulatory Agency (MHRA) has published a guide to COVID-19 tests and testing kits.

2. Types of testing available and recent evaluations

The standard PCR test for current infection is performed on machines by expert laboratory staff in a central laboratory. Other nucleic acid based tests use portable devices to provide rapid testing outside a laboratory. A list of all validated technology and their validation reports is available.

An LFD Ag test uses a colour change on a test strip, to directly detect non-nucleic acid antigens of coronavirus.

LFD Ag test sensitivity varies with viral load. When used for regular testing of asymptomatic people they are effective at identifying people with the virus when they are at their most infectious. Test sensitivity is around 88% for nasal-only swabs and 92% for throat and nose at high viral load, independent of whether administered by experienced or inexperienced users. An initial laboratory evaluation of the LFD Ag tests for COVID-19 in current use in the UK, showed that these devices have similar sensitivity for detecting Omicron, the newest variant of SARS-CoV-2, compared to previous strains of SARS-CoV2.

Validation experiments performed by the UKHSA and academics from the University of Oxford estimated a high specificity of the Innova LFD antigen test of 99.7%. However, analysis of real-world positivity rates for the Innova LFD devices found the specificity of these devices to be greater than 99.97%.

LFD antibody tests have also been developed. These indicate whether a person has had infection with COVID-19 at some point in the past, but cannot diagnose current infection. They can also not yet detect vaccine-derived antibodies.

Many LFD antibody POC tests are now available and there is great variation in their performance. When compared with laboratory ELISA antibody tests, the most promising LFD antibody tests have so far shown to be less sensitive (study 1, study 2).

There are postal self-sampling kits used in various circumstances such as for returning travellers, and in some care settings. These self-sampling kits are used by someone to take their specimen and return it to a central laboratory for testing; the samples can be tested by a variety of testing techniques depending on the purpose and laboratory that processes the swab.

3. Relevant regulations and guidance

A COVID-19 POC test must have a valid CE mark to ensure its design and manufacture achieves the performance specified for its purpose and is safe to use.

Obtaining a CE mark includes preparation of ‘Instructions for Use’ that specify whether a test should be performed by a trained professional or may be done by a lay person.

The MHRA has provided specific guidance on how to self-declare as a private COVID-19 testing provider. Following registration with the MHRA, the manufacturer places a CE mark on the product, thereby declaring that the test meets the required legal criteria.

MHRA guidance on the principles to be followed for the management and use of POC test devices emphasises that the local hospital laboratory should play a key role in developing and supporting a POC testing service.

The Advisory Committee on Dangerous Pathogens (ACDP) has provisionally classified SARS-CoV-2 as a Hazard Group 3 (HG3) pathogen. Interim guidance has been issued for the safe handling and processing of specimens from patients with possible or confirmed COVID-19. It specifies that POC tests should only be used if a proper risk assessment has been performed.

From December 2020, the 2020 Health Protection (Coronavirus, Testing Requirements and Standards) (England) Regulations require all private coronavirus test providers to be engaged with the United Kingdom Accreditation Service (UKAS), and to have achieved UKAS accreditation for coronavirus testing, no later than June 2021. Also, coronavirus testing is now exempted as a regulated activity under the Health and Social Care Act 2008 (Regulated Activities) Regulations 2014.

The Health Protection Regulations have been amended to require the reporting of positive, indeterminate, negative and void COVID-19 and influenza test results by POC service providers. UKHSA has issued reporting guidance for further information. Weekly surveillance reports are published on the UKHSA webpage.

MHRA has issued an exceptional use authorisation to DHSC to allow the use of LFD Ag POC testing of asymptomatic people. LFD Ag tests are available for free to anybody through online ordering or pharmacy collect.

Detailed LFD Ag testing guidance and toolkits, including standard operating procedures and instructional videos, are available separately for the NHS, local authority Directors of Public Health and other organisations such as schools and colleges.

4. Managing LFD (antigen or antibody) POC test results

The following is general guidance for managing the results of COVID-19 LFD Ag and antibody POC tests used as part of a clinical service.

LFD Ag tests can be taken by people at home (self-reported tests) or under the supervision of a trained operator who processes the test, reads and reports the result (assisted tests).

A range of factors may affect what an LFD Ag test result means, including:

• the level of training of the person conducting the test
• the presence or absence of possible COVID-19 symptoms
• whether the person tested has had prior laboratory confirmed SARS-CoV-2 infection
• whether the person is a contact of someone with recent laboratory confirmed SARS-CoV-2 infection
• whether the person is being tested as part of a COVID-19 outbreak investigation
• whether the person has been vaccinated with a COVID-19 vaccine

4.1 LFD antigen test results in those with COVID-19 symptoms

Anyone with the main symptoms of COVID-19 should begin self-isolation immediately and should request a laboratory PCR test through NHS Test and Trace and follow the stay at home guidance. They can take a test by either attending a testing centre or by registering and receiving a home sampling kit.

In the event that someone with any of the main COVID-19 symptoms has a positive LFD Ag test result they should follow the advice in the stay at home guidance.

4.2 LFD antigen test results in those without symptoms

If an asymptomatic person has a positive LFD Ag test result they must begin self-isolation immediately. Advice on self-isolation after a positive LFD Ag test can be found in the stay at home guidance.

Anyone who receives a negative LFD Ag test result should follow the advice on how to stay safe and help prevent the spread of COVID-19. This includes getting tested by PCR if they develop COVID-19 symptoms. Anyone who receives a negative LFD Ag test result as part of daily testing for contacts of confirmed cases should follow the advice in the guidance for household or non-household contacts.

4.3 LFD antibody test results in those who may have had COVID-19 infection previously

The use of LFD antibody POC tests to assist in the diagnosis and management of individual patients is not recommended at present, unless as a formal part of one of the programmes or pilot studies within the National Testing Programme.

Should an LFD antibody POC test result, whether positive or negative, be influencing the clinical management of an individual patient, it is essential that a more reliable laboratory ELISA antibody test is performed.

Though evidence is increasing that the presence of antibodies is protective in the short-term, it does not necessarily mean that someone is immune from catching COVID-19 infection again, particularly over longer time periods. LFD antibody tests to detect vaccine induced antibodies have not been evaluated and the tests should not be used for this purpose.