Introduction Hypovitaminosis D affects one-third to two-thirds of children and pregnant women from the Middle East and North Africa (MENA) region. Objective To evaluate in infants, children, adolescents and pregnant women, from the MENA region, the effect of supplementation with different vitamin D doses on the change in 25-hydroxyvitamin D [25(OH)D] level reached, and other skeletal and non-skeletal outcomes. Methods This is a systematic review of randomized controlled trials of vitamin D supplementation conducted in the MENA region. We conducted a comprehensive literature search in 7 databases, without language or time restriction, until November 2016. Two reviewers abstracted data from the included studies, independently and in duplicate. We calculated the mean difference (MD) and 95% CI of 25(OH)D level reached when at least 2 studies were eligible in each comparison (low (< 800 IU), intermediate (800–2,000 IU) or high (> 2,000 IU) daily dose of vitamin D, or placebo). We pooled data using RevMan version 5.3. Results We identified a total of 15 eligible trials: one in infants, 4 in children and adolescents and 10 in pregnant women. In children and adolescents, an intermediate vitamin D dose (1,901 IU/d), resulted in a mean difference in 25(OH)D level of 13.5 (95% Confidence Interval (CI) 8.1;18.8) ng/ml, compared to placebo, favoring the intermediate dose (p < 0.001). The proportion of children and adolescents reaching a 25(OH)D level ≥ 20 ng/ml was 74% in the intermediate dose group. In pregnant women, four trials started supplementation at 12–16 weeks of gestation and continued until delivery, and six trials started supplementation at 20–28 weeks gestation and stopped it at delivery. The MD in 25(OH)D level reached was 8.6 (95% CI 5.3–11.9) ng/ml (p <0.001) comparing the high dose (3,662 IU/d) to the intermediate dose (1,836 IU/d), and 12.3 (95% CI 6.4–18.2) ng/ml (p <0.001), comparing the high dose (3,399 IU/d) to the low dose (375 IU/d). Comparing the intermediate (1,832 IU/d) to the low dose (301 IU/d), the MD in 25(OH)D level achieved was 7.8 (95% CI 4.5–10.8) ng/ml (p < 0.001). The proportion of pregnant women reaching a 25(OH)D level ≥ 20 ng/ml was 80–90%, 73% and 27–43% in the high, intermediate, and low dose groups, respectively. The risk of bias in the included studies, for children, adolescents and pregnant women, ranged from low to high. Conclusion In children, adolescents and pregnant women from the MENA, an intermediate vitamin D dose of 1,000–2,000 IU seems necessary to allow for the majority of the population to reach a desirable 25(OH)D level of 20 ng/ml. Further high quality RCTs are required to confirm/refute the beneficial impact of vitamin D supplementation on various clinically important outcomes.

In the MENA region, vitamin D doses ≥2000 IU/day may be needed to reach the target 25(OH)D level ≥20 ng/ml. The long-term safety and the efficacy of such doses on various outcomes are unknown.

An increase in the incidence of subacute thyroiditis (SAT) following the COVID-19 vaccine. The aim of this report is to shed the light on different presentations of SAT postCOVID-19 vaccine while reviewing the link between the vaccine and subsequent thyroid inflammation. We present the case of a middle-aged man who presented symptoms of SAT 1-week postvaccine. He achieved euthyroidism 6 weeks later. We also present the case of a middle-aged woman with less severe symptoms of SAT 4 weeks after the vaccine. She is in the hypothyroid phase 11 weeks later. A 37-year-old male developed severe symptoms 2 weeks after the first dose and is still hyperthyroid 5 weeks later. A 36-year-old woman presented with silent SAT 3 weeks after the first dose. Cases of SAT following SARS-Cov-2 are now reported increasingly. COVID-19 can cause thyroiditis via direct cell, or alternatively though immune destruction of the thyroid in genetically susceptible individuals. Similarly, the vaccine can promote inflammation through the same mechanisms. Indeed, there is a postulated cross-reactivity between the spike protein and thyroid antigens. More-so, there is the studied vaccine adjuvant effect on the endocrine system, namely the thyroid in this case. Cases of SAT postCOVID-19 vaccines are increasingly reported. Theories are similar to COVID19-induced thyroiditis but also other mechanisms are uniquely mediated by vaccines. A low threshold should be set to diagnose SAT in patients with one or more hyperthyroid symptoms presenting 1–8 weeks postCOVID-19 vaccine.

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