The required vaccines are Tdap, MMR, Varicella, Hepatitis A, Hepatitis B and Flu. If you take those at your primary care physician's clinic, your insurance should cover. If you you have taken but don't have any records, retaking them won't have any adverse effects. Then take that record to the USCIS approved doctor for the I-693 medical exam. Usually insurance pays 100% for immunizations. If you take those at the USCIS doctor, then the insurance might not cover.