Research of Lateral flow tests performance data:

Asymptomatic testing for SARS-CoV-2 using antigen-detecting lateral flow tests

Analysis confirms lateral flow tests (LFts) are successful at identifying infectious cases of coronavirus (COVID-19) and real-world data shows LFts are capable of detecting the Delta variant.

asymptomatic-testing-for-SARS-Covid19-using-antigen-detecting-lateral-flow-tests-evidence-Oct-2020-to-May-2021

Key points summary of the report of asymptomatic testing for SARS-CoV-2 using antigen-detecting lateral flow tests:

Around a third people never develop symptoms of Covid 19. Even those who have coronavirus (COVID-19).

Testing including lateral flow tests for those without symptoms supports finding and identifying infectious cases to reduce transmission in the community.

Infectiousness can be related to the viral load. (how much virus can be found in a test sample).

Those with a high load are most likely to be infectious.

Thus this is particularly important to identify those with these high viral loads.

These people who have high viral loads are most likely to be in the infectious and transmissible stage of the virus.

Asymptomatic testing including with lateral flow tests (testing for those without symptoms) allows testers to find more people with transmissible virus.

As they have no symptoms these people will probably not know they are infectious.

By locating these cases these people can be notified, self-isolate and break the chain of transmission.

Lateral flow testing tests (LFTs), sometimes referred to as ‘rapid tests’, are well suited to mass testing for those without symptoms as they require minimal effort and almost no training.

Experiments show these tests have suitable sensitivity (how good the test is at detecting true positive cases) and specificity (how good the test is at not incorrectly giving a positive) for use within the community setting across the range of prevalence

To assess the suitability of these lateral flow tests, laboratory-based studies and in the field studies are run across different settings and environments.

This helps to better understand how to turn these tests into their most effective format of delivery.

Polymerase chain reaction (PCR) tests are used to measure viral loads and, in the real-world evaluations provide a standard for the LFTs effectiveness.

The viral load was measured and used to provide an link between the LFT result and infectiousness. Plus to allow the results of different evaluations to be compared with each other.

The Lateral Flow Tests evaluation:

The original clinical evaluations of these lateral flow tests by Public Health England (PHE) and Oxford University, published in November 2020, showed that the lateral flow tests perform best when levels of virus are at their highest. While they are accurate and sensitive enough to be used in the community and in the field.

In PHE field tests 1 and 2, individuals swabbed themselves and the samples were studied by an experienced professional to determine the Lateral flow test result (whether the test showed as positive, negative or void).

These studies showed that the sensitivity of the test increased as the viral load and by extension the likely infectiousness of the individual increased:

High Viral Loads of Covid 19:

For people with high viral loads (over 1,000,000 RNA copies per millilitre), 96% (66 of 69) were detected

Low Viral Loads of Covid 19:

For individuals with low viral loads (10,000 to 1,000,000 RNA copies per millilitre), 92% (180 of 195) were detected

Minimal Viral loads of Covid 19:

For those with minimal viral loads (less than 10,000 RNA copies per millilitre, 43% (55 of 127) were detected

Where we are with test and trace:

Applying the performance of Lateral Flow Tests to data obtained from thousands of historic users of Test and Trace.

It was calculated that Lateral Flow tests would detect the majority (83% to 89%) of known infected people who themselves had at least one PCR-positive contact.

Suggesting Lateral flow tests would pick up 83% to 89% of infectious individuals.