A Community-Based Randomized Controlled Trial on Weekly Vitamin D₃ Supplementation for Prevention of Seasonal Respiratory Illness in Transit Workers
DOI:
https://doi.org/10.61919/7jcnf569Keywords:
Cholecalciferol; Occupational Health; Respiratory Tract Infections; Supplementation; Transit Workers; Vitamin D Deficiency; Workplace Exposure.Abstract
Background: Seasonal respiratory illnesses contribute substantially to morbidity, absenteeism, and reduced productivity among transit workers because of their repeated exposure to commuters in crowded occupational environments. Vitamin D has immunomodulatory effects that may reduce respiratory infection susceptibility, but evidence from pragmatic high-exposure occupational settings remains limited. Objective: To evaluate the effect of weekly high-dose vitamin D₃ supplementation on the incidence, frequency, duration, and severity of seasonal respiratory illness among transit workers. Methods: A community-based randomized placebo-controlled trial was conducted over four months in Industrial and Urban Core Punjab. Seventy-two transit workers were randomized to weekly oral vitamin D₃ 50,000 IU or matching placebo, and 68 completed follow-up. Baseline serum 25-hydroxyvitamin D was measured, and participants were followed weekly using symptom diaries and structured interviews. Respiratory illness incidence, number of episodes, illness duration, and WURSS-21 severity scores were compared between groups. Results: Respiratory illness occurred in 14/34 participants receiving vitamin D₃ and 25/34 receiving placebo (41.2% vs 73.5%; RR=0.56; 95% CI: 0.36–0.88; p=0.01). Vitamin D₃ also reduced mean episode frequency (0.62 ± 0.70 vs 1.18 ± 0.90; p=0.02), duration (3.4 ± 1.2 vs 5.1 ± 1.6 days; p<0.001), and WURSS-21 severity score (28.6 ± 8.9 vs 41.3 ± 10.5; p<0.001). Conclusion: Weekly vitamin D₃ supplementation significantly reduced respiratory illness burden among transit workers and may serve as a practical adjunctive preventive strategy in high-exposure occupational settings
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Copyright (c) 2025 Fatima Khan, Munkishey Ali, Farkhunda Naz, Sohail Afsar Awan, Tanzeel u Rehman, Shazia Ilyas (Author)
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