Moreover, the persistence of certain autoantibodies, such as anti-U1-snRNP, anti-SS-B/La, and CHRM3 autoantibodies, in plasma has been linked to specific post-COVID symptoms, including fatigue and dyspnea [83,84]
Conclusion This systematic review and meta-analysis indicate that sublingual and oral vitamin B12 administration provide efficacy comparable to intramuscular injection in improving serum cobalamin levels and reducing hyperhomocysteinaemia
[12] Clinical manifestations, such as low blood pressure, and low-grade fevers, and dark circles around the eyes, may occur
This suggests that absorption or metabolic utilisation of B12 may differ in some South Asian individuals (Refsum et al., 2001, AJCN)