While cells can usually respond to neurotransmitters in milliseconds and cytokines in minutes to hours, cells that respond to hormones can take hours or even weeks. Since hormones can have slow and systemic actions, a dysfunctional or damaged endocrine system will generally be slow in its symptom onset and recovery. Studies have shown that spike proteins from COVID-19 infection and the vaccines can damage endocrine glands, including pituitary, thyroid, and adrenal glands, as well as reproductive organs, and many more. Cadegiani raised a concern that the slower onset of endocrine pathologies may pose difficulties in diagnosis and treatment.