Background: Although the risk for severe COVID-19 progression in children is low, this may be aggravated by the underlying disease and/or immunosuppressive drugs.

Objectives: We analyzed clinical data of COVID-19 cases among paediatric patients with rheumatic diseases reported to the BIKER registry.

Methods: The main task of the German BIKER (Biologics in Pediatric Rheumatology) registry is to monitor the safety of biologics therapies in JIA. After the onset of the COVID-19 pandemic, the survey was expanded with a standardized form to proactively interview all participating centers about the occurrence, presentation, and outcome of SARS-CoV-2- infections in children with rheumatic diseases. Interviews were conducted with 68 centers initially weekly and later biweekly.

Results: A total of 68 centres participated in the survey. Clinical data from 194 COVID-19 cases reported to the BIKER registry from 41 German and 1 Austrian pediatric rheumatology institutions between February 2020 and December 2021 were analyzed. Juvenile idiopathic arthritis (JIA, n=144) was the most common diagnosis followed by genetic autoinflammation (n=18; i.e. FMF, TRAPS, CAPS, HIDS, DADA2), systemic autoimmune diseases (n=11; i.e. SLE, dermatomyositis, vasculitis) and 16 with other rheumatic diseases (i.e. CRMO, Uveitis). 5 patients with no rheumatic disease were excluded. 104 (54%) patients were receiving conventional DMARDs, 81 (43%) received biologics, mainly TNF inhibitors (n=66 (35%)).

Of the 189 rheumatic patients with SARS-CoV2 infection, 123 (63%) were female. The mean age was 12.4+/-4.4 years in females and 13.2+/-4.1 in males. The duration of SARS-Co2 infection associated symptoms was 13.8+/-15.3 days (max. 113 days), in 35 (43%) patients they lasted for > 12 days. 46 (24%) were asymptomatic. Patients with autoinflammation and systemic autoimmunopathies reported more symptoms such as fever, head and throat ache. 4 patients only complained about dyspnea.

Only 3 patients were hospitalized and received Oxygen-supplementation. The only patients admitted to ICU, received ventilation but succumbed. This 3½-year-old patient, initially diagnosed with systemic JIA, developed fatal disease with intracranial edema and respiratory failure, as well as typical pulmonary texture changes. Prior to her SARS-CoV-2 infection, the patient was treated with MTX and low-dose steroids. Genetic testing revealed a so far unrecognized congenital immunodeficiency.

In the total JIA cohort, treatment with corticosteroids, conventional DMARDs, biologics or combinations did not influence the number of reported symptoms or the favorable outcome of the cohort. However, the duration of symptoms was lower in the TNF-treated cohort (10.4+/-6.4 days vs. 15.7 +/- 19.7 days). In the cohort with autoinflammation, fever was observed in 11 (61%). Those 6 who received IL-1-inhibitors did not show a different outcome than those 12 who did not. No case of PIMS/MISC in children with rheumatic diseases was reported.

Conclusion: Except for one patient with congenital immunodeficiency who died from her COVID-19 infection, no case of severe COVID-19 was reported in our cohort. At the time of infection, over 80% of patients in our cohort had been treated with conventional DMARDs and/or biologics. This did not appear to have a negative impact on the severity or outcome of SARS-CoV2 infection. Interestingly, no case of PIMS/MISC was observed.

Disclosure of Interests: Gerd Horneff Speakers bureau: Novartis, Pfizer, Janssen, Grant/research support from: Pfizer, Novartis, Roche, MSD, Frank Dressler Speakers bureau: Pfizer, Novartis, Abbvie, Paid instructor for: Advisory boards Novartis, Mylan, Daniel Windschall Speakers bureau: Pfizer, Novartis, Abbvie, MEDAC, Canon, Grant/research support from: Novartis, Pfizer, Sonja Mrusek: None declared, Toni Hospach: None declared, Alexander Kühn: None declared, Maria Haller: None declared, Philipp von Bismarck: None declared, Wolfgang Emminger: None declared, Peggy Ruehmer: None declared, Markus Hufnagel: None declared, Ariane Klein Speakers bureau: Novartis