Machine error has been blamed for the 40 recent false positive test results for COVID-19 in Thailandās southern province of Yala.
Dr. Opas Karnkavinpong, director-general of the Medical Science Department, told a news conference this afternoon (Wednesday) that health officials conducting COVID-19 lab tests found something unusual about the standard control protocol of the RT-PCR tests, done under the Active Case Finding (ACF) campaign.
He explained that, in the RT-PCR lab test protocol, there are two standard controls, one positive and one negative, adding that the results of the positive and negative controls must always be positive and negative respectively and, if the results deviate from this, the officials must immediately suspend the tests.
For the 40 problematic cases, the negative controls showed positive results and the tests were suspended, said Dr. Opas, adding that the specimens were then sent to the medical science centre in Songkhla province for secondary analysis, test which showed negative results.
The conflicting results meant the Medical Science Department in Bangkok conducted a third test, which confirmed the negative results.
Dr. Opas said that the lab tests are just one of the tools used in the diagnosis of COVID-19 infection, which must be complemented by a physical examination, as well as background and epidemiological investigations.
To ensure accuracy and to restore public confidence, he said that the lab at the medical centre in Songkhla province will conduct parallel tests, along with the test facility in Yala.
He added that, in order to relieve the Yala facility of the heavy workload of having to test up to 800 specimens per day, some will be sent to other facilities for testing.
