Cureus. 2021 Nov 25;13(11):e19902. doi: 10.7759/cureus.19902. eCollection 2021 Nov.
Background COVID-19 is a global pandemic. Treatment with hydroxychloroquine (HCQ), zinc, and azithromycin (AZM), also known as the Zelenko protocol, and treatment with intravenous (IV) vitamin C (IVC) have shown encouraging results in a large number of trials worldwide. In addition, vitamin D levels are an important indicator of the severity of symptoms in patients with COVID-19. Objectives Our multicenter, randomized, open-label study aimed to assess the effectiveness of HCQ, AZM, and zinc with or without IVC in hospitalized patients with COVID-19 in reducing symptom severity and duration and preventing death. Methods Hospitalized patients with COVID-19 in seven participating hospitals in Turkey were screened for eligibility and randomly allocated to receive either HCQ, AZM, and zinc (group 1) or HCQ, AZM, zinc plus IV vitamin C treatment (group 2) for 14 days. The patients also received nontherapeutic levels of vitamin D3. The trial is registered on the Australian and New Zealand Clinical Trial Registry ACTRN12620000557932 and has been approved by the Australian Therapeutic Goods Administration (TGA). Results A total of 237 hospitalized patients with COVID-19 aged 22-99 years (mean: 63.3 ± 15.7 years) were enrolled in the study. Almost all patients were vitamin D deficient (97%), 55% were severely vitamin D deficient (<25 nmol/L) and 42% were vitamin D deficient (<50 nmol/L); 3% had insufficient vitamin D levels (<75 nmol/L), and none had optimal vitamin D levels. Of the patients, 73% had comorbidities, including diabetes (35%), heart disease (36%), and lung disease (34%). All but one patient (99.6%; n = 236/237) treated with HCQ, AZM, and zinc with or without high-dose IV vitamin C (IVC) fully recovered. Additional IVC therapy contributed significantly to a quicker recovery (15 days versus 45 days until discharge; p = 0.0069). Side effects such as diarrhea, nausea, and vomiting, reported by 15%-27% of the patients, were mild to moderate and transient. No cardiac side effects were observed. Low vitamin D levels were significantly correlated with a higher probability of admission to the intensive care unit (ICU) and longer hospital stay. Sadly, one 70-year-old female patient with heart and lung disease died after 17 days in ICU and 22 days in the hospital. Her vitamin D level was 6 nmol/L on admission (i.e., severely deficient). Conclusions Our study suggests that the treatment protocol of HCQ, AZM, and zinc with or without vitamin C is safe and effective in the treatment of COVID-19, with high dose IV vitamin C leading to a significantly quicker recovery. Importantly, our study confirms vitamin D deficiency to be a high-risk factor of severe COVID-19 disease and hospitalization, with 97% of our study's patient cohort being vitamin D deficient, 55% of these being severely vitamin D deficient, and none had optimal levels. Future trials are warranted to evaluate the treatment with a combination of high-dose vitamin D3 in addition to HCQ, AZM, and zinc and high-dose intravenous vitamin C.