Background COVID-19, rheumatoid arthritis (RA) and osteoarthrosis (OA) are diseases characterized by the secretion of cytokines related to the stimulation of the inflammatory response. Objectives To identify the differences in the cytokine and matrix metalloproteinases (MMP) profile within one acute infectious disease and two chronic inflammatory rheumatic diseases. Methods Analytical cross-sectional study. RA patients under a strict follow-up program (T2T evaluated every two months), OA patients without strict clinical follow-up, evaluated once or twice a year, and Severe (mortality) COVID-19 patients were included. Eleven proteins (cytokines, MMPs and its tissue inhibitors) were quantified through Luminex multiplex assay in serum samples. Univariate and bivariate analyzes were performed. Approval of Ethics Committee and informed consent were obtained. Results A total of 108 patients with RA and OA were compared with 20 severe COVID-19 patients. There were no significant differences through the method of Kruskall–Wallis, between RA and OA patients. IL1-B and MMP-2 were significantly lower in COVID-19 patients. Levels of IL-10, IL-1RA, IL-6, MMP-1, MMP-9, and TIMP-1 were significantly higher in COVID-19 patients. There were no differences in TNF-A, TIMP-2 and INF-G. (Table 1) Table 1. Significant correlations between cytokines related to Covid-19, RA and OR. Cytokine (pg/ml) Median values RA (%) OA COVID-19 P-value IL-10 54.92 54.49 116.38 <0.0001 a Il1-RA 62.19 51.82 110.08 <0.0001 a IL1-B 67.09 55.30 46.17 0.045 IL-6 56.09 51.34 84.98 <0.0001 b 0.003 c TNF-A 17.5 14.6 16.3 NS MMP-1 d 57.84 54.84 90.81 <0.0001 b 0.045 c MMP-2 d 70.38 70.59 48.56 0.040 MMP-9 d 66.25 58.16 86.4 0.007 b TIMP-1 d 51.59 60.99 111.67 <0.0001 a TIMP-2 d 45.2 47.7 49.6 NS INF-G 5.75 5.32 3.07 NS a Between RA and Covid-19 and OA and Covid-19, without differences between RA and OA. b Between OA and Covid-19. C Between RA and Covid-19. d ng/ml. Conclusion Compared with RA and OA patients, severe COVID-19 patients have a great impact on the cytokines and MMPs addressed in this study, proving that COVID-19 patients suffer from a cytokine storm [1] when severely infected. References [1]R. Mulchandani, T. Lyngdoh, and A. K. Kakkar, “Deciphering the COVID-19 cytokine storm: Systematic review and meta-analysis,” Eur. J. Clin. Invest. , vol. 51, no. 1, pp. 1–21, 2021, doi: 10.1111/eci.13429. Disclosure of Interests None declared