Could you shift this to the right place? I don't how how to shift an open discussion to another forum. There is some immunomodulatory effects mediated by serotonin (https://www.hindawi.com/journals/jir/2015/354957/).  Medication working on serotonin receptors also alters immunofunction (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6509093/). Possible underlying infections might get adapted to this new function. In sudden withdrawal immune system can't cope the viral (or pathogen) load and