Unfortunately the researchers did not test patients for B12 deficiency (using B12, MMA and/or Hcy) prior to the study to see what percent of patients had undiagnosed metabolic B12 deficiency.  Next, they gave B12 with another vitamin (vitamin D) and a mineral (magnesium).  I disagree with giving all three as a cocktail without study arms investigating each one individually.  It would have been a better study to have 4 groups, one group for each treatment, and a 4th group containing all three.  However, this study supports the use of B12 in COVID-19.