Vitamin D Supplements for Prevention of Covid-19 or other Acute Respiratory Infections: a Phase 3 Randomized Controlled Trial (CORONAVIT)

ABSTRACT

OBJECTIVESTo determine whether population-level implementation of a test-and- treat approach to correction of sub-optimal vitamin D status (25-hydroxyvitamin D [25(OH)D] <75 nmol/L) influences risk of all-cause acute respiratory infection (ARI) or coronavirus disease 2019 (COVID-19). DESIGNPhase 3 open-label randomised controlled trial (CORONAVIT) utilising trials-within-cohorts (TwiCs) methodology. SETTINGUnited Kingdom. PARTICIPANTS6200 adults aged 16 years or older, who were not already taking vitamin D supplements at baseline. INTERVENTIONSOffer of a postal finger-prick test of blood 25(OH)D concentration with provision of a 6-month supply of higher-dose vitamin D (3200 IU/day, n=1550) or lower-dose vitamin D (800 IU/day, n=1550) to those with blood 25(OH)D concentration <75 nmol/L, vs. no offer of testing or supplementation (n=3100). Follow-up was from 17th December 2020 to 16th June 2021. MAIN OUTCOME MEASURESThe primary outcome was the proportion of participants experiencing at least one doctor- or swab test-confirmed ARI of any cause. Secondary outcomes included the proportion of participants developing swab test-confirmed COVID-19. Logistic regression was used to calculate odds ratios and associated 95% confidence intervals. RESULTSOf 3100 participants offered 25(OH)D testing, 2958 (95.4%) accepted, and 2690 (86.8%) had 25(OH)D <75 nmol/L and were sent vitamin D supplements (1356 higher-dose, 1334 lower-dose). 76 (5.0%) vs. 87 (5.7%) vs. 136 (4.6%) participants in higher-dose vs. lower-dose vs. no offer groups experienced at least one ARI of any cause (odds ratio [OR] for higher-dose vs. no offer 1.09, 95% CI 0.82-1.46; lower-dose vs. no offer 1.26, 0.96-1.66). 45 (3.0%) vs. 55 (3.6%) vs. 78 (2.6%) participants in higher-dose vs. lower-dose vs. no offer groups developed COVID-19 (OR for higher-dose vs. no offer 1.13, 0.78-1.63; lower-dose vs. no offer 1.39, 0.98-1.97). CONCLUSIONSAmong adults with a high baseline prevalence of sub-optimal vitamin D status, implementation of a population-level test-and-treat approach to vitamin D replacement did not reduce risk of all-cause ARI or COVID-19. TRIAL REGISTRATIONClinicalTrials.gov no. NCT04579640 SUMMARY BOXO_ST_ABSWhat is already known on this topic?C_ST_ABSVitamin D metabolites support innate immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory pathogens. Sub-optimal vitamin D status (25-hydroxyvitamin D <75 nmol/L) associates with increased susceptibility to all-cause acute respiratory infections (ARI) and coronavirus disease 2019 (COVID-19). Phase 3 randomised controlled trials of vitamin D to prevent COVID-19 have not yet reported. What this study addsThis phase 3 randomised controlled trial, including 6200 participants, shows that implementation of a population-level test-and-treat approach to oral vitamin D replacement at a dose of 800 IU or 3200 IU per day did not reduce risk of all-cause ARI or COVID-19 among adults with a high baseline prevalence of sub-optimal vitamin D status.