Three new studies detail "long-haul" COVID-19, one finding 203 symptoms involving 10 organ systems, another showing that more than five coronavirus symptoms in the first week of infection portends a long disease course, and one finding few long-haul–like symptoms in children.Average of 55.9 lingering symptomsIn the first study, published yesterday in the Lancet's EClinicalMedicine, a team led by University College London scientists analyzed survey responses from 3,762 COVID-19 survivors from 56 countries who still had symptoms 28 days after becoming ill.Respondents had begun experiencing symptoms before June 2020 and were surveyed from Sep 6 to Nov 25, 2020.