The case of Dr Laura Callero, the emergency nurse and Tias health councillor, who was declared free of coronavirus after initially testing positive for the disease, has raised questions about the reliability of the tests. But what do these tests actually involve?
Tests are carried out on two classes of people: those showing symptoms of coronavirus, and those who have been in contact with a confirmed coronavirus sufferer.
The test involves a sample being taken, usually from the back of the throat or the nose. If this initial test is negative, the patient is discharged; if it’s positive or inconclusive, several more samples are taken and sent to Spain’s National Microbiology Centre in Madrid for a conclusive PCR (polymerase chain reaction) test.
If this confirms the initial positive result, the patient will be fully isolated and tested further. Patients are judged to have recovered from the virus if two tests taken more 24 hours apart give negative results.
Dr Callero said “I’m happy. I always thought that what I had was just a cold – other health workers in the Canaries that I know reported fever, muscular pain and general feeling of sickness, but I was carrying on as normal, without shortness of breath or fever.” ,
False positives do occur. Another was reported in Aragon recently, but Dr Callero’s appears to be the only case so far in the Canaries. However, experts have warned that the urgency and speed of the preliminary testing may result in more false positive tests.
At the time of writing , 2,138 PCR tests had been completed for Canarian patients.
Gran Canaria: 72
La Palma: 7
La Gomera: 3
El Hierro: 0
Intensive care: 25