“One reason USCIS may grant the national interest waiver is because a physician agrees to work for a period of time in a designated underserved area.”
You must serve either in a Health Professional Shortage Area (HPSA), Mental Health Professional Area (MHPSA – for psychiatrists only), a Medically Underserved Area (MUA), or a Veterans Affairs facility, or for specialists in a Physician Scarcity Area (PSA)
You must obtain a statement from a federal agency or a state department of health that has knowledge of your qualifications as a physician and that states your work is in the public interest (This statement is known as an attestation)