Coloured transmission electron micrograph (TEM) of a SARS-CoV-2 coronavirus particle isolated from a UK case of the disease Covid-19.
Every day, rapid testing is helping us find cases of COVID-19 that we wouldn’t otherwise know about, breaking chains of transmission and potentially saving lives.
We know that rapid tests are effective in detecting people that are highly infectious and therefore pose the greatest risk to others, both with and without symptoms.
They are an absolutely crucial way to help bring down infection rates and keep them low.
The main rapid test we are using widely are Lateral Flow Devices – simple devices we can use in our own homes, in workplaces and community testing sites and which deliver a result in 30 minutes.
As with any test, there are a number of factors that can impact results, such as how the sample is taken and also the accuracy of the test. The LFDs that we are using have a high specificity, that means the number of false positives are extremely low – less than 1 in 1000 tests conducted from our studies.
However, as the prevalence of COVID-19 reduces to low levels in the population, the chance of a false positive result increases – though still remains unlikely.
During periods of low virus prevalence, we can mitigate against the risk of false positives by confirming a positive lateral flow test with another test – such as a PCR test performed in the laboratory.
This makes it highly unlikely that anyone would need to self-isolate unnecessarily, while ensuring that we can retain the benefits of rapid testing to detect true positive cases and for confirming when people are not infected.
Sourch: https://publichealthmatters.blog.gov.uk/2021/03/30/covid-19-reintroducing-confirmatory-pcr-testing/
