This article originally appeared on Focal Points and was republished with permission.
Guest post by Nicolas Hulscher, MPH
The study titled, Efficacy of vitamin D replacement therapy on 28 cases of myalgic encephalomyelitis/chronic fatigue syndrome after COVID-19 vaccination, was recently published in Nutrition:
Background
Prolonged symptoms have been reported following both COVID-19 infection and vaccination, with some cases leading to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Of 80 patients presenting to our hospital with postvaccination syndrome, 28 met the diagnostic criteria for ME/CFS. We conducted a retrospective study on these 28 patients.
Methods
We measured serum 25-hydroxyvitamin D levels in 28 patients who developed ME/CFS after COVID-19 vaccination between August 2022 and February 2024. Vitamin D replacement therapy included dietary counseling, sun exposure recommendations, and oral vitamin D supplementation. We evaluated changes in blood vitamin D levels and symptom improvement.
Results
At initial visit, 27 of 28 patients diagnosed with ME/CFS had insufficient or deficient serum 25-hydroxyvitamin D levels (16 ± 4 ng/mL, mean ± SD). Following vitamin D replacement therapy, we observed an increase in blood vitamin D levels (28 ± 5 ng/mL) associated with a decrease in ME/CFS diagnostic symptoms (from 10.3 ± 2.1 to 3.3 ± 2.0). Notably, 23 of 28 patients (82%) no longer met ME/CFS diagnostic criteria after the therapy. Among the symptoms, sleep problems showed the most improvement (71%), followed by autonomic symptoms (68%).
Conclusions
For patients developing ME/CFS after COVID-19 vaccination with insufficient or deficient vitamin D levels, appropriate vitamin D replacement therapy under medical guidance may lead to symptomatic relief. We are preparing a randomized controlled trial to evaluate the efficacy of vitamin D replacement therapy in individuals with ME/CFS who have developed vitamin D deficiency following COVID-19 infection or vaccination.
Here are the key findings:
High Prevalence of Vitamin D Deficiency in Post-COVID-19 Vaccination ME/CFS Cases
- 27 out of 28 patients (96%) had insufficient or deficient vitamin D levels before treatment.
- Mean baseline vitamin D level: 16 ± 4 ng/mL (deficient range).
- Vitamin D deficiency may be linked to immune dysfunction and post-vaccine complications.
COVID-19 Vaccine Identified as a Major Suspected Trigger
- 68% of patients developed ME/CFS symptoms immediately after receiving a COVID-19 vaccine.
- The onset of ME/CFS symptoms occurred after 1–6 doses of the vaccine, with the most cases appearing after the third dose (46%).
- 82% of patients had no history of prior COVID-19 infection, suggesting vaccination—not infection—was the primary trigger.
- Some patients faced medical gaslighting, as previous doctors dismissed their post-vaccine symptoms.
- Due to suspected vaccine-induced ME/CFS, patients were advised not to receive further COVID-19 booster shots.
Significant Symptom Improvement After Vitamin D Therapy
- 82% (23 out of 28) of patients no longer met ME/CFS diagnostic criteria following vitamin D replacement.
- Most improved symptoms:
- Sleep problems (71% improvement)
- Autonomic symptoms (68% improvement)
- Post-exertional malaise (54% improvement)
- Pathologic fatigue showed the least improvement (21%), suggesting deeper systemic dysfunction in post-vaccine ME/CFS.
Vitamin D has also demonstrated potential therapeutic benefits for other adverse events following COVID-19 vaccination. Notably, Tsang et al reported that vitamin D protects against COVID-19 mRNA vaccine-induced myocarditis.
Given the growing evidence of vitamin D’s role in mitigating post-vaccine complications, large-scale, double-blind, placebo-controlled trials are urgently needed to further evaluate its efficacy in treating COVID-19 vaccine injury syndromes.
Epidemiologist and Foundation Administrator, McCullough Foundation
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