Response to SARS-CoV-2 infection using an approach independent of symptom-based serological testing in children cohorts with selected chronic diseases

Since SARS-CoV-2 was first identified in December 2019, it has become a global pandemic at an incredible rate. The aim of this study was to perform SARS-CoV-2 serological testing in children with chronic diseases with no COVID-19 evidence. The quantitative longitudinal study using convenience selection of the patients included children (aged 0-18 years) with type 1 diabetes, bronchial asthma, cystic fibrosis and inflammatory bowel disease in Children's Clinical University hospital (CCUH) from September till December 2020, who has no epidemiological, clinical or laboratory evidence of possible COVID-19. All the patients were tested for seroprevalence of SARS-CoV-2 by Elecsys Anti-SARS-CoV-2 (Roche Diagnostics) and randomized patients - Anti-SARS-CoV-2 ELISA (IgA) and (IgG) (Euroimmune). A total of 238 patients were enrolled in the study and serological testing was performed to 232. Patients have been distributed by disease groups: 103 patients with bronchial asthma, 108 patients with diabetes, 12 patients with inflammatory bowel disease and 15 patients with cystic fibrosis. From all the 232 patients, who were serologically tested, only 3 had positive total SARS-CoV-2 antibodies, that is only 1.3%. Anti-SARS-CoV-2 positive patients were 2 patient in group of bronchial asthma and 1 with inflammatory bowel disease. Additional Anti-SARS-CoV-2 IgA and IgG were tested to randomized 83 patients enrolled in the study. 3 out of 83 (3.6%) were borderline positive for Anti-SARS-CoV-2 IgA, 2.4% had borderline positive Anti-SARS-CoV-2 IgG, 3.6% had positive Anti-SARS-CoV-2 IgA and 4.8% had positive Anti-SARS-CoV-2 IgG. SARS-CoV-2 seroprevalence is only 1.3% among children with chronic diseases enrolled in the study in CCUH, it should be noted that the number of cases with COVID-19 increased rapidly during study period in Latvia.We recommend serological testing with more than one method for patients who may benefit from it.