The National Institutes of Health (NIH) define senior and key personnel to be:
The program director/principal investigator (PD/PI) and other individuals who contribute to the scientific development or execution of a project in a substantive, measurable way, whether or not they request salaries or compensation.
The prior approval requirement for changes in status of personnel applies only to those senior/key personnel named in the Notice of Award (NoA).
For more information about NIH personnel definitions and examples, review the related NIH Frequently Asked Questions (FAQs) on senior/key personnel.