CHICAGO — People with long COVID-19 who visited a Northwestern Medicine clinic were still experiencing symptoms such as headaches, dizziness, fatigue and brain fog for a median of 15 months after first falling ill, despite never needing hospitalization, according to a new Northwestern study. The study looked at 52 patients who were seen at Northwestern’s Neuro COVID-19 clinic between May 2020 and November 2020, who initially had mild COVID-19 symptoms. Study senior author Dr. Igor Koralnik said the study is the first to look, over such a long time period, at neurological symptoms in people who…