Determinants of serum 25-hydroxyvitamin d levels in healthy young adults living in the Western Cape, South Africa

Background: Vitamin D deficiency is fast emerging as a global pandemic. In South Africa few studies have been conducted to determine the vitamin D status of the healthy population.Methods: This prospective study with an analytical component investigated vitamin D status of healthy undergraduate students at two time points (winter and summer) at Stellenbosch University. Serum 25(OH)D was determined, anthropometric measurements taken and dietary vitamin D intake estimated (food-frequency questionnaire). Skin tone was determined (Fitzpatrick skin type classification), and a skin reflectometry device used to measure dermal melanin content.Results: Results of 242 students indicated a mean serum 25(OH)D of 63.80 ± 41.35 ng/ml and a high prevalence of vitamin D sufficiency (88%). Significantly more females experienced suboptimal vitamin D levels than males (18 vs. 5%; p < 0.01). Participants with lighter skin tones had higher levels of 25(OH)D than those with darker skin tones (chi-square = 24.02; p = 0.02). The majority (60.74%) had a normal BMI, although there was no significant relationship between BMI and serum 25 (OH)D (Spearman's r=­0.11; p = 0.09). Total mean dietary vitamin D intake was 7.99 ± 13.81 mcg, with 87.2% having inadequate intake (< 15 mcg). The relationship between total vitamin D intake and serum 25(OH)D was found to be significant in winter (p < 0.001) and summer (p = 0.01). Serum vitamin D levels were significantly higher in the winter phase (p < 0.001).Conclusions: A low prevalence of vitamin D deficiency was found amongst healthy young adults, despite low dietary vitamin D intakes. Significant relationships were found between serum 25(OH)D and gender, skin tone and vitamin D intake. Further studies need to be conducted, especially in high-risk groups, before results are applied to the greater South African public

Feasibility and acceptability of conducting HIV vaccine trials in adolescents in South Africa: Going beyond willingness to participate towards implementation

Background. HIV/AIDS remains a leading cause of death in adolescents (aged 15 - 25 years), and in sub-Saharan Africa HIV-related deaths continue to rise in this age group despite a decline in both adult and paediatric populations. This is attributable in part to high adolescent infection rates and supports the urgent need for more efficacious prevention strategies. In particular, an even partially effective HIV vaccine, given prior to sexual debut, is predicted to significantly curb adolescent infection rates. While adolescents have indicated willingness to participate in HIV vaccine trials, there are concerns around safety, uptake, adherence, and ethical and logistic issues.Objectives. To initiate a national, multisite project with the aim of identifying obstacles to conducting adolescent HIV vaccine trials in South Africa (SA).Method. A simulated HIV vaccine trial was conducted in adolescents aged 12 - 17 years across five SA research sites, using the already licensed Merck human papillomavirus vaccine Gardasil as a proxy for an HIV vaccine. Adolescents were recruited at community venues and, following a vaccine discussion group, invited to participate in the trial. Consent for trial enrolment was obtained from a parent or legal guardian, and participants aged 16 - 17 years were eligible only if sexually active. Typical vaccine trial procedures were applied during the five study visits, including the administration of vaccination injections at study visits 2, 3 and 4.Results. The median age of participants was 14 years (interquartile range 13 - 15), with 81% between the ages of 12 and 15 years at enrolment. Overall, 98% of screened participants opted to receive the vaccine, 588 participants enrolled, and 524 (89%) attended the final visit.Conclusions. This trial showed that adolescents can be recruited, enrolled and retained in clinical prevention trials with parental support. While promising, these results were tempered by the coupling of sexual-risk eligibility criteria and the requirement for parental/guardian consent, which was probably a barrier to the enrolment of high-risk older adolescents. Further debate around appropriate consent approaches for such adolescents in HIV prevention studies is required