In a word, no. Although the government is widening the roll out of lateral flow testing across schools and care homes, there isn’t yet the supporting evidence needed to determine that this type of testing is accurate.
Pilot studies showed that the lateral flow test misses a significant proportion of symptomless cases. Considering that the lateral flow method is being rolled out for mass testing, in which many more people who may have the virus will be asymptomatic, this is concerning.
According to the BMJ article, although the government claims that the lateral flow test detects 77% of cases, the data on which this is based comes from a arguably flawed study which involved symptomatic cases. Figures from the Liverpool pilot study show 60% of infected people without symptoms went undetected. In studies of testing on students in Birmingham, only 3% of those who would have tested positive using a PCR test were detected by the lateral flow test.
PCR testing is still considered the gold standard for sensitivity and specificity, the two measures scientists base the accuracy of testing on. Rapid access tests, such as lateral flow, compared against results of PCR testing are not considered to be as accurate.
Why is lateral flow testing being rolled out?
With such high numbers of covid cases circulating in the population, testing is needed on a huge scale in order to begin to reopen schools and businesses and return to a more normal way of living. But it’s not only the scale of testing, it’s the speed that makes this option attractive.
Because lateral flow testing produces a result in 30 minutes, it’s a much more preferable option when it comes to keeping the country moving. But unfortunately, it isn’t a silver bullet. While the results might be fast, they are a false economy if they’re not also accurate.
It has also been claimed that the government acquired mass stock of lateral flow tests near the beginning of the Covid-19 outbreak, when less was known about the accuracy of the test, and is looking to use up those supplies.
What are the risks of using lateral flow testing?
Lateral flow tests are an attractive option for mass testing because of the speed at which the results are available. Without the need to send samples off to a laboratory to be processed, the hope is that businesses and schools can begin to open up sooner and be able to keep a handle on new cases in the community.
While being able to test large volumes of people quickly and regularly, is desirable, the use of lateral flow testing for this purpose runs a higher margin of error.
False negative results happen for various reasons. The person taking the test may have a lower viral load or they might have had difficulties collecting the swab sample, reducing the chances of a true positive result. Additionally, the application of the sample to the testing strip adds further opportunity for the testing to produce a less accurate result, compared to a sample which is processed by a trained professional in a laboratory.
False results = false confidence.
The government has championed the use of negative tests to enable visits to relatives in care homes, returning to work or staying in school and other social and sporting activities. But the risks remain high if the results don’t give the full picture and may lead to a false sense of security.
A reported case of a Covid-19 outbreak, caused when a symptomatic healthcare worker continued to work due to false reassurance from a negative lateral flow test, indicates the type of situation which could occur from inaccurate tests.
Additionally, with so much still unknown and unproven about the efficacy of lateral flow testing, there are concerns that false information is being circulated. It has been reported that letters have been sent to schools and parents stating that lateral flow tests are “as accurate in identifying a case as a PCR test.”
Lateral flow test results are not recognised by Test and Trace.
NHS Test and Trace is designed to automatically send out an alert to self-isolate and start contact tracing. But the system is only told to do this when infections are confirmed by PCR tests.
If more lateral flow tests are used in the population, over PCR testing, the efficacy of Test and Trace will be much lower.
What are the safest options for testing right now?
Currently, if you have symptoms of Covid-19 or have been exposed to someone who has the virus, you can get a free PCR test from the NHS. You can either order a home-to-laboratory kit or arrange to visit an approved testing centre.
If you do not have symptoms but are concerned that you have been exposed to the virus, the NHS recommends that you order a private covid-19 PCR test from the government list of approved providers.