While it strongly stands by the integrity of the results issued by its molecular laboratories, the Philippine Red Cross (PRC) on Tuesday, Sept. 21, acknowledged the possibility of false positive results “since no test is 100 percent accurate.”
PRC said this following the allegation of “false positive” Reverse transcription polymerase chain reaction (RT-PCR) test results from the PRC Subic Molecular Laboratory.
In cases of false positive, PRC said that it adheres to the advice of the Department of Health (DOH) “to err on the side of caution and treat all positive results as true positive.”
This, PRC said, is designed to protect everyone - including the clients and their families and co-workers. “This is especially true for healthcare workers who are constantly at risk of exposure to the virus,” it added.
Standardized procedures
To date, PRC has 13 molecular laboratories nationwide. “The test methodology and procedures are standardized in all its laboratories,” the organization added.
PRC explained that the Research Institute for Tropical Medicine (RIRM) sends proficiency test (PT) samples to the laboratory using a random-blind method.
“In this control method, RITM sends PRC samples for which RITM already knows the results and compares these with the results that the PRC will issue,” the Red Cross said.
PRC added that it is subjected to RITM’s PT “every time a laboratory opens.
Likewise, issuance of the License to Operate by the DOH is dependent on passing the proficiency test with a 100 percent score.
PRC said that all its molecular laboratories obtained 100 percent for proficiency tests they underwent from the time the first molecular laboratory opened in April 2020 and in May 2021.
This, it added, is part of the 2021 External Quality Assurance Program (Post Accreditation) for RT-CR Detection of SARS COV-2.
“This test and the strict implementation of quality standards in all PRC laboratories base on protocols set upon by manufacturers, in line with the standards set forth by DOH and the RITM, assure the public of the accuracy of test results released by PRC,” the Red Cross maintained.
During his pre-recorded public address on Sept. 20, President Duterte turned to PRC by questioning its testing facilities - especially the results issued by PRC Subic.
Clients may have ‘truly been negative’
PRC explained that the testing samples alluded to in the hearing at the Lower House pertain to samples taken at the Unihealth-Baypointe Hospital and Medical Center in Subic Bay Freeport Zone by their personnel and tested at the PRC Molecular Laboratory also in Subic Bay Freeport Zone.
“Of the 48 samples, 45 turned out positive, triggering a complete re-run and a manual process to eliminate the possibility of erroneous results, which may be caused by cross-contamination,” PRC said.
PRC noted that is an example of a situation where the organizations --- on its own initiative and at its own expense --- “requires an automatic re-run by its molecular labs in order to ensure the accuracy of results.”
On the second run, PRC said the results “came out exactly the same.”
The PRC said that Subic laboratory followed “standard operating procedures and quality assurance guidelines” as it has done for all 122,000 samples processed by the Subic lab from July 1, 2020 to September 3, 2021.
“The timing of tests done relative to exposure to the virus are factors that may produce different results,” PRC said. “The negative result of the tests in question came from specimens collected after three days, which may be one such factor for the negative result,” it added.
In this case, PRC said the sampling was performed by Baypointe Hospital personnel. The test kits, extraction method, and the thermocycler (PCR machine) used by the testing laboratory, it added, are also “factors that may influence” the results.
PRC maintained that in this specific case, “clients may have truly been negative already by the time their second sample was taken.”