Dynamics of fecal zonulin levels in COVID-19 and in the post-covid period in children

Fecal zonulin is currently used as a biomarker of intestinal permeability. Objective. To assess the state of intestinal permeability in a novel coronavirus infection (COVID-19) in children based on the determination of fecal zonulin levels. Patients and methods. Fecal zonulin levels were assessed in 35 children with COVID-19, which was mild in most of them. Fecal sampling was performed at the time of diagnosis and 14 days after the start of observation. Patients were then randomized into two groups. Group 1 (study, n = 19) received Maxilac® Baby synbiotic (2 sachets once a day) for 1 month, group 2 (control, n = 16) did not receive any probiotics, prebiotics, and adsorbents for a month; the third stool sampling was performed 1 month after the second. The study was carried out by enzyme immunoassay using the IDK Zonulin ELISA test system (Immundiagnostik AG, Germany). Results. Fecal zonulin levels were 77.38 ± 12.59 ng/mL at the beginning of the disease, 76.26 ± 13.10 ng/mL on day 14, and 82.64 ± 11.99 ng/mL after one month (p1–2 = 0.75; p1–3 = 0.04; p2–3 = 0.04). Children who received Maxilac® Baby for a month did not have significant increases in zonulin levels (76.26 ± 13.10 ng/mL and 79.02 ± 11.87 ng/mL; p = 0.40), while the control group demonstrated significantly elevated zonulin levels (76.26 ± 13.10 ng/mL and 87.95 ± 10.96 ng/mL; p = 0.048). Conclusion. A month after the coronavirus infection, the intestinal permeability in children increases significantly, whereas it does not change during the course of the disease. Administration of Maxilac® Baby synbiotic in children who had a mild-tomoderate coronavirus infection and did not receive antibiotics effectively prevents intestinal permeability disorders in them. Key words: children, SARS-CoV-2, zonulin, coronavirus infection, intestinal permeability, COVID-19