Go for Vit C+Zinc Supplements.
Vitamin C 500mg daily + Zinc 5mg supplements like Our Daily or Cimune. For
Vitamin D, go for 400 IU tablets per day, however Vitamin D must be taken under supervision of a Doctor or a Dietitian. People with Blood pressure issues must not consume 60000 IU weekly tablets. Other adults may consume 60K IU one tablet per week e.g. Torflash.
Next Steps
You can consult me directly on Practo or via Google search via my website for a diet for enhanced immunity and proper supplementation guidance.
Health Tips
Do not consume any vitamins in excess than prescribed without supervision.