Efficacy and Safety of Vitamin D Supplementation to Prevent COVID-19 in Frontline Healthcare Workers. A Randomized Clinical Trial.

BACKGROUND: Associations between vitamin D (VD) deficiency and the risk of SARS-CoV-2 infection have been documented in cross-sectional population studies. Intervention studies in patients with moderate to severe COVID-19 have failed to consistently document a beneficial effect. OBJECTIVE: To determine the efficacy and safety of VD-supplementation in the prevention of SARS-CoV-2 infection in highly exposed individuals. METHODS: A double-blind, parallel, randomized trial was conducted. Frontline healthcare workers from four hospitals in Mexico City, who tested negative for SARS-CoV-2 infection, were enrolled between July 15 and December 30, 2020. Participants were randomly assigned to receive 4,000 IU VD (VDG) or placebo (PG) daily for 30 d. RT-PCR tests were taken at baseline and repeated if COVID-19 manifestations appeared during follow-up. Serum 25-hydroxyvitamin D3 and antibody tests were measured at baseline and at day 45. Per-protocol and intention-to-treat analysis were conducted. RESULTS: Of 321 recruited subjects, 94 VDG and 98 PG completed follow-up. SARS-CoV-2 infection rate was lower in VDG than in PG (6.4 vs. 24.5%, p <0.001). The risk of acquiring SARS-CoV-2 infection was lower in the VDG than in the PG (RR: 0.23; 95% CI: 0.09-0.55) and was associated with an increment in serum levels of 25-hydroxyvitamin D3 (RR: 0.87; 95% CI: 0.82-0.93), independently of VD deficiency. No significant adverse events were identified. CONCLUSIONS: Our results suggest that VD-supplementation in highly exposed individuals prevents SARS-CoV-2 infection without serious AEs and regardless of VD status.

Novel missense mutation of the FAM83H gene causes retention of amelogenin and a mild clinical phenotype of hypocalcified enamel.

OBJECTIVE: Amelogenesis imperfecta (AI) is a group of clinically and genetically heterogeneous inherited conditions, causing alterations in the structure of enamel and chemical composition of enamel matrix during development. The objective of this study was to compare the clinical, radiographic, histological and immunohistochemical phenotypes of subjects affected with hypocalcified AI from three Chilean families and identify causal mutations in the FAM83H gene. DESIGN: The diagnosis was made using clinical, radiographic, histological and genealogical data from the patients, who were evaluated according to the classification criteria by Witkop. PCR and Sanger sequencing of the complete coding sequence and surrounding intron regions of the FAM83H gene were conducted. The structural study of the affected teeth was performed with light microscopy, scanning electron microscopy and immunohistochemistry. RESULTS: The probands of the three families were diagnosed with hypocalcified AI, but in only one of them the missense variant p.Gly557Cys was identified. This variant was not present in the SNP database or in 100 healthy controls and segregated with the disease in the affected family. Using light microscopy, a normal prismatic structure was observed in all three cases. However, the ultrastructure was found to be affected in two of the cases, showing persistence of organic matter including amelogenins. CONCLUSIONS: These results suggest that FAM83H missense mutation reported in one of the families analyzed in this study might cause a phenotype of hypocalcified enamel more attenuated with retention of amelogenin.