Retrospective 242 hospitalized patients in the USA showing adjusted hazard ratio for zinc treatment, aHR 0.66 [0.41-1.07].  notes that the study would be more informative if baseline serum zinc levels were known.
Yao et al., 7/22/2020, retrospective, USA, North America, peer-reviewed, 9 authors.
risk of death, 34.0% lower, RR 0.66, p = 0.09, treatment 73 of 196 (37.2%), control 21 of 46 (45.7%), adjusted per study, multivariate Cox regression.
Effect extraction follows pre-specified rules
prioritizing more serious outcomes. For an individual study the most serious
outcome may have a smaller number of events and lower statistical signficance,
however this provides the strongest evidence for the most serious outcomes
when combining the results of many trials.