Abu Dhabi: Until last year, it was not a widely-known test outside medical circles. But ever since the coronavirus outbreak struck, the RT-PCR (real-time reverse transcription-polymerase chain reaction) test for COVID-19 has become common knowledge.
The screening itself is conducted via a nasal swab and the laboratory test is a real-time assessment to detect SARS-CoV-2 genetic material or RNA from a person’s upper and lower respiratory specimens.
In the laboratory, the technique combines reverse transcription of the RNA genetic material from the nasopharyngeal sample into DNA and amplifies these DNA targets using PCR. This amplification helps measure the amount of a specific virus RNA in the sample. In the case of COVID-19, the RNA being detected pertains to the novel coronavirus — SARS-CoV-2.
While there are other ways to test for COVID-19, the RT-PCR test remains the gold standard and the UAE has been one of the top-most countries in deploying them to screen for COVID-19. Like South Korea, it quickly set up multiple drive-through screening centres across the country, all of which offered RT-PCR tests. The tests were also made available at health-care facilities and teams of health-care professionals went door-to-door in Abu Dhabi and in certain parts of Dubai, screening residents for COVID-19.
Gulf News spoke to Dr Gurdeep Dhatt, chief medical officer at Purehealth, a leading medical laboratory operator in the UAE, to learn more about the test and its associated precautions.
When did Purehealth start testing for COVID-19?
Purehealth started offering laboratory services for the UAE Ministry of Health and Prevention in October 2017. As the largest laboratory network in the country, Purehealth has been offering RT-PCR testing for COVID-19 since February 2020. Supporting the nation during the COVID-19 crisis was possible due to the foresight and anticipatory planning by the senior leadership of Purehealth. We started deploying our screening teams as early as February 2020, where we were on the frontline screening incoming passengers at airports across the country using RT- PCR tests.
How effective are the RT-PCR tests when screening for COVID-19?
Most importantly, the only recognised Covid19 testing method by the World Health Organization and the US Centers for Disease Control and Prevention is testing through Real Time PCR (RT-PCR test). This test is the most effective test to detect the SARS-CoV-2 virus. The ability of PCR to produce millions of copies of a target sequence from trace amount of DNA allows for a very small sample of DNA to be amplified to a large enough amount to study in detail. Hence, PCR is an extremely powerful diagnostic tool.
How many testing stages are carried out on samples? What happens during each one?
There are six testing stages for RT-PCR testing.
Sample collection and transportation
Samples are collected by experienced trained professionals and transported to the testing laboratories under safe and controlled conditions. Individual samples are labelled by a barcode which enable the sample to be traced to the individual from whom the sample was collected.
Samples are checked for individual demographics, date and time of collection, location referring the sample, and number of samples received.
Samples are then carefully logged into the laboratory information system.
Samples are prepared, following the [equipment] manufacturer instructions prior to testing.
Samples are transferred to a fully-automated Viral Nucleic Acid instrument to extract the RNA from the nasopharyngeal swab collection media. A fully automated platform then mixes the extracted RNA with reagents required to perform the PCR test.
Samples are loaded onto special RT-PCR instruments for detection of the SARS-CoV-2.
Results are reported through an integrated laboratory information system.
What are the precautions taken at each stage, such as temperature controls and handling protocol, to keep the samples and safe?
[First of all], temperature is monitored during the transportation and all the testing/analytical phases — pre-analytical, analytical and post-analytical phases. Specimens are transported to the laboratory in low temperature — between 2 to 8 degrees Celsius — using ice bags with a triple packing system. The samples are always handled, transported and treated as infectious. In addition, the transportation process of a double packing system and a third outer layer of packaging ensure that the packaging is protected from physical damage during transportation and this also reduces the chances of contamination.
What personal protection measures do lab personnel follow?
Personal protective equipment is available to laboratory personnel at all times, including laboratory coats, aprons, gloves, scrubs and N95 masks.
When they are about to leave, laboratory coats are removed and placed in the designated areas in the laboratory. Laboratory coats are also not worn outside the laboratory, and beyond the designated areas within the laboratory. Any contaminated coat is removed and kept separately.
In addition, the gloves that are provided are of the appropriate size: They cover the hands completely while allowing for flexibility and proper grip. These are always discarded in waste disposal bags for biohazard material, and gloves are removed when leaving the work area.
For eye protection, goggles are used while performing activities with potential of a splash, such as while transferring large volumes of liquids, carrying out maintenance on various instruments, de-capping of specimen lids, etc.
[Finally], N95 fit-tests are conducted for all laboratory staff to test the seal between the respirator’s facepiece and the face.
What structural protective measures are taken at the lab?
A unidirectional workflow is applied in the laboratory as a protective measure. So workflow between rooms and areas is from clean to contaminated areas.
Dedicated laboratory coats are supplied for each area, and gloves are changed between areas.
Laboratory rooms are facilitated with negative pressure, preventing the infectious particles from escaping, which ensures an infection-free environment.
In addition, specimen testing is performed in Biosafety Cabinet Class II A2 with HEPA filters, to reduce the chances of contamination.
Meanwhile, laboratory ventilation is kept on 24/7. Cooling systems are operated normally as there are no direct implications on COVID-19 spread. But attention is given, as in normal circumstances, to monitoring the condition of filters and maintaining proper replacement rate of indoor air.
Hygiene services have also been enhanced. So special attention is paid to the application of cleaning and disinfection measures in common areas like rest rooms, halls, corridors, and elevators, and on frequently-touched surfaces like handles, elevator buttons, handrails, switches, and doorknobs.
What are the specifics about the Purehealth lab network, specifically in terms of COVID-19 testing capacity?
Purehealth operates 118 laboratories located at hospitals, primary health-care centres, visa screening centres, the National Newborn Screening centre, and four dedicated COVID-19 labs across the UAE. The dedicated COVID-19 labs incorporate 200 new equipment installations to provide a daily testing capacity of upto 80,000 tests, which is [known to be] the largest testing capacity outside China. [We] have recently completed more than 2.7 million COVID-19 PCR tests, with the help of more than 1,000 professionals across our network.