Background and objective Vitamin D is important as the interaction between vitamin D and its receptors at the immune cells stimulates innate and adaptive immunity. Deficiency in vitamin D is associated with increased susceptibility to infection and it is commonly found in Indonesia. Several studies indicate the potential of vitamin D supplementation against Coronavirus Disease 2019 (COVID-19), particularly in combating the proinflammatory situation as well as coagulopathy. This study aims to evaluate the supplementation of vitamin D in COVID 19 patients, particularly the changes in hematology parameters and other clinical parameters.

Method A double-blind randomized clinical trial is conducted among moderate COVID 19 patients. High-dose of vitamin D is given orally in the intervention group, compared with a low dose of vitamin D. Hematology parameters, D Dimer, conversion time on Polymerase Chain Reaction (PCR) test, and clinical symptoms are assessed

Hypothesis High Dose vitamin D shows a better hematology parameter, short PCR conversion time, and faster clinical recovery

Population:

The COVID 19 patients admitted to hospital with moderate severity, defined as Individuals who show evidence of lower respiratory disease during clinical assessment or imaging and who have an oxygen saturation (SpO2) ≥94% on room air at sea level.

Methodology:

A double-blind randomized clinical trial allocated with simple random sampling

Intervention:

5000 International unit/ IU of vitamin D3 (Cholecalciferol) given orally twice daily (total 10000 IU per day)

Comparison group:

1000 International unit/ IU of vitamin D3 (Cholecalciferol) given once daily

Variables to be collected :

• The level of 25-hydroxyvitamin D in the blood
• D-Dimer
• Platelet-to-Lymphocyte Ratio (PLR)
• Total Lymphocyte Count (TLC)
• Neutrophil to Lymphocyte Ratio (NLR)
• Age
• Sex
• Comorbidities including chronic diseases
• Body Mass Index
• Handgrips Strength
• Anticoagulant administration
• Clinical Symptoms and days to recover
• Length of Stay
• Time to PCR conversion where the PCR is conducted every two days

Sample size and recruitment

Following the study in Saudi Arabia, the sample size was derived from the days to achieve recovery, where the group who received the 5000 D had an average recovery day of 6.2 ± 0.8. The intervention is expected to shorten the average recovery days up to 10%. Using the difference between the two means, the effect size derived from this result is 0.775. With 5% type 1 error and 90% power and equal allocation (1:1), the number needed for each group is 30 participants

Participants are allocated consecutively according to the permutation of the simple random sampling.

Proposed statistical analysis

1. Descriptive statistics
2. Repeated measures ANOVA
3. a Linear mixed model or generalized estimated equation will be applied to adjust the variables in the baseline

1. Inclusion Criteria:

   1. Belongs to moderate case
   2. Diagnosed using PCR test
   3. Showing a vitamin D deficiency (<30 ng/dL).

2. Exclusion Criteria

   1. Pregnant or doing breastfeeding
   2. Patient under specific medication (Tuberculosis, or HIV, or malignancy) or undergo hemodialysis
   3. Receive vitamin D supplementation prior to allocation.
   4. Tested negative less than 5 days after receiving vitamin D
   5. Creatinine >2,0 mg/dL
   6. Blood Calcium >10,5 mg/dL.
   7. Ventilated
   8. Hypersensitive to vitamin D
   9. Consistent desaturation <85% with oxygen supplementation and require High-Flow Nasal Cannula (HFNC)/Extracorporeal membrane Oxygenation (ECMO) via a ventilator.
   10. Refuse to attend blood examination for follow up

No data sharing will be done

Masking for participants is conducted by preparing a similar chewing tablet (appearance including the color and taste). The care provider will not aware as the tablet has been unpacked. Outcome assessors are unaware of the allocation and only statistician knows the allocation