People with confirmed COVID-19 should be retested four weeks after symptoms first appear.br This is to minimize their risk of spreading the virus, according to the authors of a new study.br In more than 1,100 infected adults in Italy, retesting four weeks later showed a stark difference.br UPI reports that the research showed 61 no longer had the virus in their systems.br However, a second retest to confirm the initial findings showed some false negatives.br A false negative refers to when the virus still was present but it is not detected by the test.