“…14,40,41 Four studies had a retrospective design, 13,[36][37][38] four studies a prospective design, 12,[39][40][41] one study reported a prospective COVID-19 group and a retrospective control group 14 and one study reported on prospectively assessed data on a retrospective cohort. 42 Two studies reported that FD and/or IBS criteria were applied after a follow-up of <6 months, 13,40 five after a follow-up of 6 months 14,38,39,41,42 and three after a follow-up of more than 6 months. 12,37,38 Six studies reported of hospitalised COVID-19 patients, 12,14,38,[40][41][42] three of hospitalised and/or outpatients COVID-19 subjects 13,36,37 and one study did not report this data.…”