The claim: WHO changed COVID-19 testing guidelines; one PCR test is not enough to diagnose COVID-19 Since its global emergence over a year ago, the PCR test – a molecular test that diagnoses infection by detecting genetic material – has been used to distinguish the COVID-19 positives from the negatives. But according to one Facebook post, the PCR test may not be enough. "Anyone catch the WHO website? Yesterday, on the day of inauguration, the recommendations for PCR testing changed," writes Facebook user Maria Dawn Tyler on Jan. 21. "Now, a positive PCR test is NOT enough to confirm a positive case. You need a second test AND a clinical correlation, which means be symptomatic, and have a doctor tell you that you have covid based on your symptoms, for it to count as a positive case."