Some evidence suggests that vitamin C and D supplementation might prevent or treat respiratory infections, but their effectiveness is still being tested with COVID-19
Although no public health agencies have recommended vitamins C or D as standard COVID-19 treatments, both have demonstrated some ability to shorten the length of respiratory infections by boosting the strength of the immune system. Vitamin D has also demonstrated the ability to reduce the risk of respiratory infection, especially in individuals who are vitamin D deficient. Many in the scientific and medical communities are recommending vitamin D supplementation or getting at least 15 minutes of sun exposure a day to prevent deficiencies.