Vitamin D may be a central biological determinant of COVID-19 outcomes. The objective of this quasi-experimental study was to determine whether bolus vitamin D3 supplementation taken during or just before COVID-19 was effective in improving survival among frail elderly nursing-home residents with COVID-19. Sixty-six residents with COVID-19 from a French nursing-home were included in this quasi-experimental study. The “Intervention group” was defined as those having received bolus vitamin D3 supplementation during COVID-19 or in the preceding month, and the “Comparator group” corresponded to all other participants. The primary and secondary outcomes were COVID-19 mortality and Ordinal Scale for Clinical Improvement (OSCI) score in acute phase, respectively. Age, gender, number of drugs daily taken, functional abilities, albuminemia, use of corticosteroids and/or hydroxychloroquine and/or antibiotics (i.e., azithromycin or rovamycin), and hospitalization for COVID-19 were used as potential confounders. The Intervention (n = 57; mean ± SD, 87.7 ± 9.3years; 79%women) and Comparator (n = 9; mean,87.4 ± 7.2years; 67%women) groups were comparable at baseline, as were the COVID-19 severity and the use of dedicated COVID-19 drugs. The mean follow-up time was 36 ± 17days. 82.5% of participants in the Intervention group survived COVID-19, compared to only 44.4% in the Comparator group (P = 0.023). The full-adjusted hazard ratio for mortality according to vitamin D3 supplementation was HR = 0.11[95%CI:0.03;0.48],P = 0.003. Kaplan-Meier distributions showed that Intervention group had longer survival time than Comparator group (log-rank P = 0.002). Finally, vitamin D3 supplementation was inversely associated with OSCI score for COVID-19 (β=-3.84[95%CI:-6.07;-1.62], P = 0.001). In conclusion, bolus vitamin D3 supplementation during or just before COVID-19 was associated in frail elderly with less severe COVID-19 and better survival rate.

维生素 D 可能是 COVID-19 结果的主要生物学决定因素。这项准实验性研究的目的是确定在 COVID-19 期间或之前服用推注维生素 D3 补充剂是否能有效提高 COVID-19 的虚弱老年疗养院居民的生存率。这项准实验研究包括来自法国疗养院的 66 名 COVID-19 居民。“干预组”被定义为在 COVID-19 期间或前一个月接受过推注维生素 D3 补充剂的那些人，“比较组”对应于所有其他参与者。主要和次要结果分别是 COVID-19 死亡率和急性期临床改善有序量表 (OSCI) 评分。年龄、性别、每天服用的药物数量、功能能力、白蛋白血症、使用皮质类固醇和/或羟氯喹和/或抗生素（即阿奇霉素或罗瓦霉素）以及因 COVID-19 住院被用作潜在的混杂因素。干预组（n = 57；平均 ± SD，87.7 ± 9.3 年；79% 女性）和比较组（n = 9；平均，87.4 ± 7.2 年；67% 女性）在基线时具有可比性，COVID-19 也是如此严重程度和专用 COVID-19 药物的使用。平均随访时间为 36 ± 17 天。干预组 82.5% 的参与者在 COVID-19 中幸存下来，而比较组中只有 44.4% (P = 0.023)。根据补充维生素 D3 的死亡率的完全调整风险比为 HR = 0.11 [95% CI:0.03;0.48]，P = 0.003。Kaplan-Meier 分布显示干预组比比较组有更长的生存时间（对数秩 P = 0.002）。最后，补充维生素 D3 与 COVID-19 的 OSCI 评分呈负相关（β=-3.84[95%CI：-6.07；-1.62]，P = 0.001）。总之，在 COVID-19 期间或之前补充维生素 D3 与 COVID-19 严重程度较低且存活率较高的虚弱老年人相关。