Vitamin D 10 x better than Flu Vaccine if you have very low vitamin D
Vitamin D Is More Effective Than Flu Vaccine, Study Says Mercola
Meta-analysis of 25 randomized controlled trials
Number needed to treat = 4 if vitamin D level had been < 10 ng
Meta-analysis of 25 randomized controlled trials
Number needed to treat = 4 if vitamin D level had been < 10 ng