We found that plasma levels of syndecan-1 at T1 (>260 ng/mL) (p = 0.003) (Figure 2A), at T2 (>1018 ng/mL) (p = 0.03) (Figure 2B), and at T3 (>461 ng/mL) (p = 0.007) (Figure 2C) were associated with an increased 60-day mortality rate in patients with COVID-19. Here, SDC1 is linked to COVID-19.