Serum levels of hsa-miR-29a-3p, hsa-miR-31-3p and hsa-miR-126-3p are reduced with increased severity of COVID-19, and the relative expression levels of COL5A3, ZMYM5 and CAMSAP1 are also increased with increased severity of COVID-19. The gene discussed is COL5A3; the disease is COVID-19.