May I ask which Mayo Clinic & which Doctor ordered the test? I finally got a response from an Infectious Disease Dr. in LA and he said a test for "neutralizing antibody levels" would be helpful, but are not commercially available and I should contact the CDC & Pfizer for advice. I emailed both this am, but doubt they'll be able to lead me to a test if they reply. I will make a video appt. w/ a Mayo doctor, but need to know which one is likely to be informed on SIRVA issues. Thank you so much for sharing information.