The SARS-CoV-2 virus responsible for the COVID-19 pandemic has generated an explosion of interest both in the mechanisms of infection leading to dissemination and expression of this disease, and in potential risk factors that may have a mechanistic basis for disease propagation or control. Vitamin D has emerged as a factor that may be involved in these two areas. The focus of this article is to apply our current understanding of vitamin D as a facilitator of immunocompetence both with regard to innate and adaptive immunity and to consider how this may relate to COVID-19 disease. There are also intriguing potential links to vitamin D as a factor in the cytokine storm that portends some of the most serious consequences of SARS-CoV-2 infection such as the acute respiratory distress syndrome. Moreover, cardiac and coagulopathic features of COVID-19 disease deserve attention as they may also be related to vitamin D. Finally, we review the current clinical data associating vitamin D with SARS-CoV-2 infection, a putative clinical link that at this time must still be considered hypothetical.

SummaryFracture probabilities derived from the surrogate FRAX model for Armenia were compared to those from the model based on regional estimates of the incidence of hip fracture. Disparities between the surrogate and authentic FRAX models indicate the importance of developing country-specific FRAX models. Despite large differences between models, differences in the rank order of fracture probabilities were minimal.ObjectiveArmenia has relied on a surrogate FRAX model based on the fracture epidemiology of Romania. This paper describes the epidemiology of fragility fractures in Armenia used to create an Armenia-specific FRAX model with an aim of comparing this new model with the surrogate model.MethodsWe carried out a population-based study in two regions of Armenia (Ararat and Vayots Dzor representing approximately 11% of the country’s population). We aimed to identify all low-energy fractures: retrospectively from hospital registers in 2011–2012 and prospectively in 2013 with the inclusion of primary care sources.ResultsThe differences in incidence between the surveys with and without data from primary care suggested that 44% of patients sustaining a hip fracture did not receive specialized medical care. A similar proportion of forearm and humeral fractures did not come to hospital attention (48 and 49%, respectively). Only 57.7% of patients sustaining a hip fracture were hospitalized. In 2013, hip fracture incidence at the age of 50 years or more was 201/100,000 for women and 136/100,000 for men, and age- and sex-specific rates were incorporated into the new “authentic” FRAX model for Armenia. Compared to the surrogate model, the authentic model gave lower 10-year fracture probabilities in men and women aged less than 70 years but substantially higher above this age. Notwithstanding, there were very close correlations in fracture probabilities between the surrogate and authentic models (> 0.99) so that the revisions had little impact on the rank order of risk.ConclusionA substantial proportion of major osteoporotic fractures in Armenia do not come to hospital attention. The disparities between surrogate and authentic FRAX models indicate the importance of developing country-specific FRAX models. Despite large differences between models, differences in the rank order of fracture probabilities were minimal.

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Background Vitamin D plays a critical role in skeletal development and maintenance, thus sufficiency is an important goal for public health programs. Given the absence of foods fortified in vitamin D in Armenia, we hypothesized that vitamin D insufficiency would be widespread. Methods We conducted a random modified cluster model survey of vitamin D status of women in the country. We measured 25-hydroxyvitamin D [25(OH)D] by liquid chromatography mass spectrometry in dried blood spot samples and utilized a questionnaire to assess lifestyle factors. Results In summer, we sampled 1206 participants from 40 communities in Armenia. Mean 25-OH D level among women aged 18–24 was 20 ± 8 ng/mL; aged 25–64 was 21 ± 7 ng/mL; and >65 was 18 ± 8 ng/mL. The country-wide mean of the entire female population was 20 ± 8 ng/mL. A majority (>54%) had 25-OH D levels <20 ng/mL with nearly 13% having 25-OH D levels <12 ng/mL. Participants who reported calcium, vitamin D, or multivitamin supplementation had higher levels of 25-OH D (p values 0.004, 0.0002, and 0.03 respectively) as did pre- vs. postmenopausal women (p = 0.01), pregnant vs. nonpregnant women (p = <0.0001), and women who had experienced a sunburn in the past year (p = 0.004). Conclusion In Armenia, there is a high prevalence of vitamin D insufficiency. This information provides data that can be used to inform public health directives to address this pervasive threat to optimal health.

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