PRL and COVID-19: In a validation cohort of 153 patients with COVID-19 treated in the intensive care unit, we focused on prolactin (PRL) and toll-like receptor 3 (TLR3), among RNAs that have a strong association with prognosis, and evaluated the accuracy for predicting survival of PRL-to-TL3 ratios (PRL/TLR3) with the areas under the receiver operator characteristic (ROC) curves (AUC).