How Coronavirus Disease 2019 Vaccination Affects the Level of Vitamin D in Serum and Hair

This study examined the effects of COVID-19 vaccination on vitamin D levels in serum and hair among 80 participants in Egypt, divided by vaccine type (Pfizer, Sinopharm, AstraZeneca, and Sinovac). It found a significant decrease in serum vitamin D levels after the first dose, with an increase after the second dose, except for the Pfizer group. Hair vitamin D levels decreased significantly after the first dose and showed a minor, nonsignificant increase after the second. Hair loss was reported by 65% of participants after the first dose, worsening in 73% after the second, particularly with AstraZeneca. The study suggests a link between vaccination, vitamin D levels, and hair loss, recommending monitoring vitamin D to prevent complications, though it notes the small sample size as a limitation.