New research has discovered that coronavirus tests may be finding dead traces from weeks-old infections, resulting in false positives that inflate the scale of the pandemic.
The study was carried out by experts from the University of Oxford’s Centre for Evidence-Based Medicine and the University of the West of England. It found there was a risk of “false positives” because of how Covid-19 testing is being conducted.
The scientists discovered that, despite people with Covid-19 being infectious for only around a week, one test used to detect the disease can still give a positive reading weeks after the patient has recovered.
The team examined 25 studies on the widely used polymerase chain reaction test, which is used to determine if someone has the virus in their system. The test takes a sample from a suspected Covid-19 case and uses a process that increases the amount of DNA, or genetic material, in the sample, to enable it to be examined.