February 2023 Covid Antibody Update

It has been a year since my youngest son got sent home after a close contact exposure to Covid-19 despite having natural immunity (postinfection immunity) after all of us got the virus in November 2021. At the time, the federal policy was centered around faulty research that one’s natural immunity to Covid-19 only lasted 90 days.

Having taken epidemiology for my Hopkins MPH, I knew it was likely incorrect that you lose your antibodies in 90 days. I also knew that focusing on your antibody count left out the more efficacious part of the immune system which has memory and allows for a proliferation of your immune system after being exposed again.

But with the politically charged nature of Covid-19 conversation, I decided just to measure our antibody levels regularly and report it here to see just how long the antibodies stayed around.

Since my last update in October, there has been more research comparing natural immunity with vaccine-mediated immunity including a CDC-funded study released last month by researchers at the CDC.

Published in the Journal of Infectious Diseases, the study found that natural immunity provides 76 percent protection against Covid-19-associated hospitalizations during the surge of the Omicron variant. With the mRNA-based Moderna or Pfizer vaccines, a 39 percent protection was seen for those without a prior infection.

After getting our blood taken at LabCorp, which we’ve used every time except for the first measurement, we found that all of our antibody levels have dropped. Mine dropped 8%, my oldest son’s dropped 47%, and my youngest son’s dropped 32%. So, seven months after I last had Covid-19, I still have a strong antibody level. Stay tuned for our next test in a April or May!

My levels:


February: 71.4 AU/mL

March: 213.9 U/mL (different lab and different units than February)

May: 205.1 U/mL

June: 5822 U/mL

July: 5478 U/mL

August: 4030 U/mL

October: 2885 U/mL


February: 2635 U/mL


My youngest son's levels:


February: 56.8 AU/mL

March: 133.9 U/mL (different lab and different units than February)

May: 142.3 U/mL

June: 7525 U/mL

July: 3887 U/mL

August: 2315 U/mL

October: 1239 U/mL


February: 837 U/mL


My oldest son's levels:


February: 82.2 AU/mL

March: no test

May: 725 U/mL, diluted (different lab and different units than February)

June: 728 U/mL

July: 807 U/mL 

August: 6150 U/mL

October: 3826 U/mL


February: 2365 U/mL


  • David Roberts

    SABINA, my test cost $70 with insurance. In terms of memory T-cells, those are very hard to detect. There is a regular T-cell test that came out in 2022, however, I don’t know much about it as it’s new.

  • David Roberts

    Tim – I hear you. However, if that was their intention, why was the policy structured so that children who were in that same situation, but had been vaccinated, did not have to quarantine? My point in raising the story was to show how public policy set by bureaucrats does not follow the science.

  • Tim

    Sending your son home is not faulty practice. Yes, B cell and T cell memory are there to protect us, but with fewer antibodies and an unknown “dose” of Corona, there is a small period of time that your son could’ve spread the virus. Yes, he was protected, but that’s not what it’s about.

  • Sabina

    Thanks for your diligence and exploration of this minimally covered topic.. Have you ever done any T-cell testing? And can you comment on what the impact of being able to determine T-Cell contribution towards longer term immunity. I had Covid during the very first wave that hit California in late 2019 early 2020 and nothing since, even with repeated exposures. I’m really curious, although the tests are a bit cost prohibitive still.

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