A total of 320 patients from four out of six studies were tested for transferrin saturation, and the statistical difference was not significant (SMD, 0.06; 95% CI [-0.17, 0.28]; <i>P</i> = 0.64).<h4>Conclusion</h4>Severe COVID-19 cases had higher serum levels of hepcidin and ferritin, and lower serum iron, without significant differences in transferrin saturation. Here, TF is linked to COVID-19.