No further positive cases of Covid-19 in the Western Isles

NHS Western Isles can confirm that two individuals in the Western Isles received ‘false positive’ test results this week.

Essentially, two individuals received positive results from the a mainland laboratory, which were re-tested through the NHS Western Isles laboratory and were confirmed negative.

The mainland laboratory system was designed to provide rapid results for a large number of screening tests.  Where a result is a ‘weak positive’ in someone without risk factors for exposure to Covid-19, a confirmatory test is recommended.  

The confirmatory test that is used by NHS Western Isles in the local laboratory is called a Cepheid test which is considered to be the ‘gold standard’ in testing for Covid-19 and is used as the system to ‘retest’ as necessary.  Where this test is negative, the mainland laboratory test is regarded as a ‘false positive’.

In the two cases this week, confirmatory tests have shown that Covid-19 was not detected. We wish to reassure our local communities that public health risk assess each result and all such tests are thoroughly investigated.