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Positive or negative? Diagnosing COVID-19

A photo story from the lab

21-10-20

Image 1/1 : Waiting for the result

The spring of 2020 was an extraordinarily busy period for our colleagues of the Department of Clinical Sciences, namely those in our Clinical Reference Laboratory. This included: evenings and weekends for the team, the reorientation of several lab technicians, who work on other diseases, towards diagnosing COVID-19, and brought the enlistment of extra hands and minds from the Unit of Virology of the Department of Biomedical Sciences.

P³ article

Logo of the P³ magazine

This article was published in the 11th edition of the biannual P³ magazine.

This is because the pandemic saw our diagnostics being under high demand for SARS-CoV-2 — the strain of the virus that causes COVID-19 —, with the lab servicing hospitals from the Antwerp region and Médecins Sans Frontières (Doctors Without Borders) in its project with homeless people in Brussels.

So, what happens to a sample and how is COVID-19 diagnosed in a laboratory?

1. For safety, samples marked CORONA arrive directly at the lab. During the April peak, the lab received up to 60 samples a day. Numbers by June were down to around ten.

2. Lab technician Lara Balcaen wears two pairs of gloves and protective sleeves to work in a biosafety cabinet. Here she inactivates the suspected COVID-19 samples, so that no live virus remains. The cabinet is an enclosed, ventilated workspace protecting her from any (potentially) hazardous microorganisms.

3. To deactivate the samples, Lara adds buffers and enzymes. Lab technician Amina Taibi passes reagents and samples to her, which allows Lara to keep her potentially contaminated gloved hands inside the biosafety cabinet during the entire procedure.

4. Once inactive, samples go into an automated instrument for RNA extraction. RNA stands for ribonucleic acid and it is where the genetic information of the virus is encoded. Following extraction, lab technician Fatima Zajmović-Huseinović adds the RNA to a mix prepared in the ‘clean room’, a space where test reagents cannot be contaminated by other DNA/ RNA of previous tests. RNA/DNA contamination is the ‘horror story’ of genetic diagnostics as it can lead to false positive results and misdiagnosis.

5. Fatima puts the mix with the extracted RNA in ‘the PCR machine’. PCR stands for ‘polymerase chain reaction’. The PCR machine amplifies the genetic sequence of SARS-CoV-2, so that there is enough genetic material for an accurate detection of the virus and diagnosis of COVID-19.

6. After 4-5 hours, the results are ready for final validation by the clinical biologist (here Dr Marjan Van Esbroeck). Once validated, results are sent to the requestors.

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