Sorry about that. It isn't really anything to do with the vaccines. It is simply something that may help others, since some unfortunate few (very small %) are even getting "long covid" from just the vaccine alone.

Niacin appears to be very well studied, but not in the context of post-viral illnesses. But there are a mountain of papers which may help to explain why it works. Here are a few:

Underlying lack of niacin and establish indicated use: https://academic.oup.com/bib/article/22/2/1279/5964187 https://clinmedjournals.org/articles/jide/journal-of-infecti...

Lipids in covid: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7869689/ Sars CoV 2 entry to cells: https://www.nature.com/articles/s42255-020-00324-0 Replication etc: https://journals.plos.org/plospathogens/article?id=10.1371/j... Nicotinic acid’s effects on lipids: https://www.eurekaselect.com/126340/article