It was a Covid 19 Spike Antibody test

Since I had no antibody response from my 2 Pfizer shots in January and February, my hematologist and my family doctor both recommended that I get revaccinated with the Moderna vaccine.Since access to vaccines have been totally opened up, it was no problem scheduling. First shot was on April 8 and produced a high antibody response. Second shot scheduled next week.

Yes, I had both doses of the Pfizer vaccine but no antibody response.

My family doctor recommended another vaccination. Why is it not possible?

Had my 2nd Moderna shot today.