A review of 56 randomized clinical trials found that psychotherapy may be effective in reducing inflammation. The trials included several different types of interventions, including cognitive behavior therapy (CBT), CBT plus medication, grief and bereavement support, a combination of two or more psychotherapies, and psychoeducation, among others. CBT was the best at boosting the immune system, followed by multiple or combined interventions. The benefits of CBT on the immune system lasted for at least six months following treatment.

https://www.eurekalert.org/pub_releases/2020-06/uoc--cbt060220.php

Shields GS, Spahr CM, Slavich GM. Psychosocial Interventions and Immune System Function: A Systematic Review and Meta-analysis of Randomized Clinical Trials. JAMA Psychiatry. Published online June 03, 2020. doi:10.1001/jamapsychiatry.2020.0431 https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2766707