Govt release new lateral flow test data
Lateral flow tests have been freely available for some time. The aim is to test people who don't have symptoms to find cases and break transmission chains.
Although the tests have weaknesses, they do have a role in virus control. This is because they offer quick results and are much cheaper to use than PCR testing.
To date, only limited data has shown the accuracy of the tests. The "Liverpool" study found a sensitivity of 40%, but it was based on only 78 participants.
A Cochrane analysis of 64 different studies found that test sensitivity in symptomatic people ranged from 34% to 88%, with an average of 72%.
Jon Deeks, Professor of Biostatistics at the University of Birmingham and the Cochrane review's lead author predicted more false positives and fewer true positive results as infection levels fall.
The latest data
Now data published by the Department of Health & Social Care has shown the results from the first two weeks of testing in secondary schools using Innova tests.
The results indicate that the tests are indeed finding more false positives than true positives (62% were false positives in the first week). There was 1 positive per roughly 6,900 tests done.
All tests have limits
It is important to balance to the positive effects of the tests with their potential harms. This can be a subjective opinion but as more data is released it is becoming easier to have a better informed debate.
Benefits to lateral flow tests
1. Rapid results
2. Portable kits
3. Easy to use
4. Less expensive than PCR
Potential risks from lateral flow tests
1. Missed cases
2. False positives
3. False reassurance
The MHRA has expressed concern about the tests being used as 'green light' tests i.e. if your result is negative you cannot be certain you are not infectious. This is of importance if people are being tested before coming to work.
Testing does not replace risk management
Because lateral flow tests have known weaknesses they cannot be a substitute for infection control measures.
If the aim is to break chains of transmission, the simple steps are currently likely to be the most effective for businesses; good hygiene, social distancing, PPE and rapid testing of any symptomatic cases via the NHS.
If infection rates in the community rise again then justification for using lateral flow tests will increase (and the risks will lower), as the likelihood of false-positive results will reduce.
About Occupational Health Assessment Ltd
Occupational Health Assessment Ltd provides rapid access to occupational health support for businesses across the United Kingdom.
With a unique occupational health assessment service (https://occupationalhealthassessment.com/