– Dr. Anthony emphasises that PCR tests from approved facilities should be used

THE antibody rapid tests which are used to detect the body’s antibody response to COVID-19, should not be used for diagnostic purposes, according to Minister of Health Dr. Frank Anthony.

In a recent interview with the Guyana Chronicle, Dr. Anthony said that there are different types of rapid tests — the antibody rapid test and the more recently developed antigen rapid tests — which are able to detect the presence of COVID-19 instead. Antibodies are produced by the body’s immune system when it detects harmful substances called antigens.

These antibodies may take up to several days before they are produced, because the body first has to be infected and then the human body reacts afterwards. So, if an antibody rapid test is used to test an individual for COVID-19, Dr. Anthony highlighted, “at that stage, it is not so much about active infection, it will probably tell you that you were infected.”

It is for this reason he emphasised that the antibody rapid test should not be used for diagnostic purposes (that is, to determine whether someone has COVID-19), but perhaps, it may be used for screening purposes. The Polymerase Chain Reaction (PCR) test, on the other hand, is the global “gold standard” for detecting the coronavirus, and not just the antibodies.

“The ministry has not been using the old rapid tests (the antibody rapid tests), only PCR, but there are other institutions in Guyana that have been using antibody testing and we have repeatedly said that these should be used for screening purposes, not diagnostic purposes, but I guess people don’t listen to us,” Dr. Anthony lamented.

Recently, however, Dr. Anthony highlighted that 20,000 rapid antigen tests ordered for selective hinterland regions will increase the testing capacity in those areas. These antigen rapid tests (not to be confused with the antibody rapid tests) would be able to detect the presence of the virus and not merely the presence of the antibodies produced by the body.

“The PCR is still the gold standard, but these rapid tests can at least give you a clear indication whether this person is positive or not,” the minister said, but he noted that there is a slim margin of error.

He also explained that the use of these antigen rapid tests is important, particularly in the hinterland regions, because the current testing system is tedious. In these outlying areas, nasal samples are taken, stored and eventually sent to Georgetown for testing at the National Public Health Reference Laboratory (NPHRL). The samples are processed and then the results are sent back to the regions.

“That takes too much time,” Dr. Anthony said, adding, “(The antigen rapid tests) are going to change the dynamic of the testing out there and so we can respond faster to patients.”

Unfortunately, months ago, the antibody rapid tests were increasingly used for diagnostic purposes. Dr. Seepersaud Chatterdeo, one of Guyana’s prominent paediatricians, passed away after contracting COVID-19. He had taken an antibody rapid test, as this provided him with results much faster than a PCR test, and that would have allowed him to take care of his patients sooner — once he was not positive. That test showed that he was negative, however.

Dr. Chatterdeo’s unfortunate experience illustrates why the antibody test should not be used for diagnostic purposes. “If you’re just five days or six days and you just got exposed, that’s the time the virus is now multiplying in your body and PCR tests are the only ones that are going to give you a positive test,” Dr. Anthony said.

APPROVED LABS ONLY

In a recent interview with the Department of Public Information (DPI), Minister Anthony also warned that individuals should be wary of private institutions offering the PCR tests, since the Eureka Medical Laboratory is the only private laboratory permitted to do this test. This lab was inspected and deemed capable of offering the service.

Dr. Anthony disclosed that there are now some institutions that are purportedly offering PCR testing while not being appropriately licensed. The Guyana Chronicle understands that there are at least two other private medical centres, aside from the Eureka Lab and the NPHRL, which are offering PCR testing.

The issue with other institutions conducting the gold standard test is that they may not have the adequate capacity to offer the test.