The disclosure, however, raises other questions about the credibility of the test operation in the United Kingdom, which included laboratories struggling to source chemicals and equipment, with the government purchasing millions of tests. unusable antibodies and frontline healthcare workers who cannot access tests.
The PHE scientist, speaking anonymously, said that while there appears to be no problem with the accuracy of the positive results, internal tests appear to be less sensitive than commercial kits, such as the one developed by the company Swiss Roche.
PHE disputed this, with a spokesperson saying, “There is no evidence to support that commercial tests are more accurate than the current PHE test. We believe performance is comparable to CE marked tests currently available [tests]. “
The internal PHE document, dated April 11, indicates that, as per common practice, laboratories are expected to switch to commercial kits by April 23, now that these tests are available.
For laboratories unable to immediately migrate to commercial kits, the document describes the immediate actions that need to be taken, noting that “discordant results” have been identified between PHE tests and “new / improved tests”.
“There is a wide variety of molecular platforms, reagents, kits and test performance conditions in PHE and NHS laboratories,” says the document. He then points out “evidence of quality assurance difficulties for key reagents due to global supply chain problems”, that shortages of swabs may have an impact on test performance and that enzyme performance deteriorates. are “degraded compared to the original validation performance”.
The document asks staff to retest the ambiguous results with a different kit to avoid incorrectly calling a negative result.
When approached by the Guardian, PHE said a recent consecutive comparison of its internal and commercial tests revealed 35 differences in results on 1,165 samples. When PHE updated a component in its own test, the number of discordant results was reduced to 15, he said. No information was given as to whether these results were classified as false negative or false positive.
A PHE spokesperson added, “The UK was one of the first countries outside of China to develop testing capacity for a new coronavirus. The test is regularly reviewed and compared to commercial tests that arrive on the market and is reliable and effective. The deployment of the PHE test is the fastest deployment of a new test in recent history and we continue to make improvements. “