Effect of a test-and-treat approach to vitamin D supplementation on risk of all cause acute respiratory tract infection and covid-19: phase 3 randomised controlled trial (CORONAVIT).

OBJECTIVE: To determine the effect of population level implementation of a test-and-treat approach to correction of suboptimal vitamin D status (25-hydroxyvitamin D (25(OH)D) <75 nmol/L) on risk of all cause acute respiratory tract infection and covid 19. DESIGN: Phase 3 open label randomised controlled trial. SETTING: United Kingdom. PARTICIPANTS: 6200 people aged ≥16 years who were not taking vitamin D supplements at baseline. INTERVENTIONS: Offer of a postal finger prick test of blood 25(OH)D concentration with provision of a six month supply of lower dose vitamin D (800 IU/day, n=1550) or higher dose vitamin D (3200 IU/day, n=1550) to those with blood 25(OH)D concentration <75 nmol/L, compared with no offer of testing or supplementation (n=3100). Follow-up was for six months. MAIN OUTCOME MEASURES: The primary outcome was the proportion of participants with at least one swab test or doctor confirmed acute respiratory tract infection of any cause. A secondary outcome was the proportion of participants with swab test confirmed covid-19. Logistic regression was used to calculate odds ratios and associated 95% confidence intervals. The primary analysis was conducted by intention to treat. RESULTS: Of 3100 participants offered a vitamin D test, 2958 (95.4%) accepted and 2674 (86.3%) had 25(OH)D concentrations <75 nmol/L and received vitamin D supplements (n=1328 lower dose, n=1346 higher dose). Compared with 136/2949 (4.6%) participants in the no offer group, at least one acute respiratory tract infection of any cause occurred in 87/1515 (5.7%) in the lower dose group (odds ratio 1.26, 95% confidence interval 0.96 to 1.66) and 76/1515 (5.0%) in the higher dose group (1.09, 0.82 to 1.46). Compared with 78/2949 (2.6%) participants in the no offer group, 55/1515 (3.6%) developed covid-19 in the lower dose group (1.39, 0.98 to 1.97) and 45/1515 (3.0%) in the higher dose group (1.13, 0.78 to 1.63). CONCLUSIONS: Among people aged 16 years and older with a high baseline prevalence of suboptimal vitamin D status, implementation of a population level test-and-treat approach to vitamin D supplementation was not associated with a reduction in risk of all cause acute respiratory tract infection or covid-19. TRIAL REGISTRATION: ClinicalTrials.gov NCT04579640.

Fourier transform infrared studies of heterogeneity, photodegradation, and lignin/hemicellulose ratios within hardwoods and softwoods.

There is little information available on the variation in lignin content of growth rings in hardwoods. This study examines whether infrared microscopy can detect intra-incremental differences in the chemical composition of three hardwoods (R. pseudoacacia, P. Americana, and G. triacanthos) and the effect of such differences on the delignification of the hardwoods during weathering. Earlywood has higher lignin content than latewood in R. pseudoacacia and P. americana, but the opposite was found for G. triacanthos. The delignification of the earlywood and latewood during weathering varied for the three species. It was greater in the earlywood of R. pseuoacacia, whereas in P. americana and G. triacanthus it was more pronounced in latewood. Differences in density and lignin content of earlywood and latewood help explain these differences. In addition, a deconvoluting software package was used to determine whether it is possible to estimate the lignin/hemicellulose ratio in softwoods and hardwoods. Results from the 1760-1580 cm(-1) region provided data that can be used to estimate the lignin/hemicellulose ratio of softwoods and hardwoods. This information can be obtained far more easily using infrared microscopy than with conventional wet chemical techniques, potentially allowing characterization of greater numbers of species than has hitherto been possible.