Stem cells derived from a baby's umbilical cord can help save the lives of the sickest COVID-19 patients, results from a small new clinical trial suggest. Severely ill COVID patients who received two intravenous doses of stem cells three days apart were much more likely to survive and recover quickly, researchers found. … After one month, 91% of patients in the stem-cell-treated group had survived compared to 42% in the control group. Among patients younger than 85 years old, everyone treated with stem cells survived.