Everything else the review included, 35 of 36 studies, was done in animals, much of it by a single Croatian research group going back to the 1990s1
Management strategies: Rotate injection sites preventing localized reactions, inject after eating reducing nausea risk, start lower doses titrating up gradually, take with food and plenty of water, monitor blood pressure if known hypertension, discontinue immediately if signs of allergy (hives, difficulty breathing, facial swelling)
This may occur if antimetabolites for the vitamin are employed in the treatment of neoplasia
However, there are side effects patients may experience from the injections
Research is ongoing to better understand how oral delivery compares to other forms
Reactivation of herpesviruses during COVID-19: a systematic review and meta-analysis