et al., JAMA Netw Open., doi:10.1001/jamanetworkopen.2021.4117 (Peer Reviewed)
Retrospective 4,638 individuals with vitamin D levels within 1 year before COVID-19 testing, showing higher risk of COVID-19 PCR+ for vitamin D deficient individuals, and lower (but not statistically significant) cases for individuals using vitamin D supplementation.
Meltzer et al., 3/19/2021, retrospective, database analysis, USA, North America, peer-reviewed, 6 authors.
risk of COVID-19 case, 34.6% lower, RR 0.65, p = 0.11, high D levels 61 of 1097 (5.6%), low D levels 118 of 1251 (9.4%), adjusted per study, >40ng/mL vs. <20ng/mL, Table 2, Model 2.
risk of COVID-19 case, 36.0% lower, RR 0.64, p = 0.38, high D levels 6 of 131 (4.6%), low D levels 239 of 3338 (7.2%), supplementation, >=2,000IU/d.
risk of COVID-19 case, 31.1% lower, RR 0.69, p = 0.16, high D levels 15 of 304 (4.9%), low D levels 239 of 3338 (7.2%), supplementation, >=1,001IU/d.
risk of COVID-19 case, 8.9% lower, RR 0.91, p = 0.56, high D levels 60 of 920 (6.5%), low D levels 239 of 3338 (7.2%), supplementation, >=1IU/d.
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.