Background: Belgium suffered considerably from the COVID19 pandemic with high hospitalisation rates during 2 periods: a first wave in March and April 2020, and a second starting from October until the end of 2020. Measures of lowering social interaction were taken throughout 2020 and intensified during the first and second wave when needed. This pandemic could have influenced the access to care and advanced therapies for patients with Rheumatoid Arthritis (RA). In the electronic platform “Tool for Administrative Reimbursement Drug Information Sharing” (TARDIS), data from all Belgian RA patients on biologic and targeted therapy are collected during the submission of a request for initiation and prolongation of reimbursement for these drugs. Objectives: to investigate the effect of the COVID19 pandemic on the monthly prescription behaviour of a new advanced therapy in 2020 by comparing it to 2019. Methods: Patients were selected for this analysis if they started a new TNFi, B/T cell therapy, IL6 inhibitors or tsDMARD therapy in the TARDIS registry in 2019 or in 2020. Rheumatologists request reimbursement via the online TARDIS tool, which is considered here as a new drug prescription. Prescription behaviour was compared between 2019 and 2020, between bionaive and bioexperienced patients, and between the different drug classes Results: In 2019, 2949 patients were prescribed any new advanced therapy, including 1153 TNFi, 469 B/T cell therapy, 436 IL6 inhibitors and 891 tsDMARDs. In 2020, 2998 patients were prescribed any new advanced therapy including 1233 TNFi, 382 B/T cell therapy, 496 IL6 inhibitors and 887 tsDMARDs. On a monthly basis, on average 246 and 250 new advanced therapies were prescribed in 2019 and 2020 respectively. Monthly deviations from this average in 2019 ranged from -19% to +16%. Monthly deviations from this average in 2020 ranged from -50% to +30%. Figure 1A shows the monthly prescription of new advanced therapies in 2019 and 2020. For bionaive and bioexperienced patients, the same trend can be ...