CMO: TT testing meets WHO guidelines

File photo: Chief Medical Officer Dr Roshan Parasram.
File photo: Chief Medical Officer Dr Roshan Parasram.

The testing rate for covid19 in TT is well within WHO guidelines, even as concerns mount given the increase of covid19 cases in the country.

The percentage of positive tests to number of unique samples completed saw a decrease from three per cent to 1.8 per cent since July 20 when the recent spike in cases began. The WHO said, in countries where extensive testing has taken place, between three and 12 per cent of tests have been positive.

Up to July 20, before the current spike in covid19 cases began, 4,557 unique samples had been tested in the public health system, from which 137 people had tested positive. This totaled three per cent of tests done. By August 3, two weeks later, the total number of positive cases had jumped to 182, out of a total of 6,984 samples. This accounted for 2.61 per cent of samples taken. In that two-week period, there were 2,427 samples, of which 45 tested positive – a ratio of 1.85 per cent.

In the March 30 WHO media briefing, epidemiologist Dr Maria Van Kerkhove said,

“If you get to a point where a tiny percentage of tests are positive, then the danger is you're either looking in the wrong place, it's reassuring, or you have to be very careful to ensure you can keep up that level of testing so it's an issue of balancing the use of your tests against their value. We would certainly like to see countries testing at the level of ten negative tests to one positive as a general benchmark of a system that's doing enough testing to pick up all cases.”

Chief Medical Officer Dr Roshan Parasam, at Monday’s covid19 briefing, said TT had been following the WHO/PAHO guidelines for testing using clinical criteria, as well as the criteria developed by the Caribbean Public Health Agency in the early days of the pandemic. He said as the spread of the virus progressed, the clinical criteria were amended. He said people who presented with severe, acute respiratory illnesses were also being tested. Parasram said once cases began to appear in TT, tracing and testing of primary, secondary and tertiary contacts was done, with follow-up for 14 days leading to increased testing.

“If our number of cases is low, and the number of people presenting with respiratory illnesses is low, we test based on who presents to us, and those linked to any contact bearing in mind that testing has always been, and will continue to be, a voluntary process where people can say no.

“You would have noticed over the last two weeks the number of community tests has increased significantly – the reason being, we have cases and we have a lot of primary, secondary and tertiary contacts to test.”

He said there have been no covid19 deaths recorded outside the public health system, as bodies at the Forensic Science Centre are swabbed to ensure covid19 was not the cause of death.

Parasram said while serological or antibody testing was being discussed as a method of future testing, it would be used for surveillance, research and cross-reactivity. He said while the polymerase chain reaction (PCR) test detected the presence of the covid19 virus from days one to ten of symptoms being experienced, the serology test detected the presence of the virus from days ten to 30, and could therefore be used to determine whether people previously had the virus without showing symptoms and how long the virus lingered in the body of recovering patients.

Health Minister Terrence Deyalsingh said serological testing was previously not used in TT because the kits available in March were not specific to the virus and gave false positives.

“The testing was inaccurate in the earlies – 50 to 75 per cent inaccurate. Can you imagine the panic that would have engendered? Now, three months later, the kits are more accurate and we can talk about introducing serological testing.”

Comments

"CMO: TT testing meets WHO guidelines"

More in this section