If you think you have had COVID-19, get an antibody blood test before your vaccine. It may save you a shot!

As I wrote last week, I believe most people who’ve already been infected with COVID-19 probably need only one dose of the vaccine to achieve strong immunity. Two recent studies from England provide data to support that concept.

One study shows that antibody responses to the spike protein that prevent binding of the virus to human cells (and therefore prevent infection) are as strong in people who’ve received one dose of the vaccine after active infection as people who have not been infected and received two doses of vaccine. This reinforces that the single dose of the vaccine serves as a booster to the immunity developed by natural infection.

SARS-CoV-2 anti-S protein antibody levels in individuals with no previous infection are similar to levels in individuals who have had a prior mild SARS-CoV-2 infection. After the vaccine the protective antibody levels in those with previous SARS-CoV-2 infection are more than 140-fold greater than at time of peak infection. Statistical analysis was by unpaired two-tailed test. U=unit. NS=non-significant. 

The other study documents that both antibody and T cell immune responses are significantly boosted by a single dose of the vaccine and are equivalent to what’s seen in people who have received two doses of the vaccine. This was true regardless of the age of the individual or other preexisting conditions. So it appears anyone with a prior infection has baseline immunity that can be enhanced by a single dose of vaccine.

people from age 20 to 60 years with prior cCOVID-19 infection (purple dots) have higher antibody levels after a single vaccine dose than those without prior infection (black dots).

This does not mean that people who have not had a COVID-19 infection only need one dose a vaccine. If anything it suggests that those individuals need both doses of vaccine to develop strong immunity that protects them not only from current coronavirus strains but emerging variants.

On the other hand, if you have any suspicion that you may have had COVID-19 in the past it would make sense to get an antibody test before getting the vaccine. If you have antibody to COVID-19 it’s likely that you would only need a single dose of any of the coronavirus vaccines. 

This not only saves vaccines but prevents needless immunization with the associated soreness for the vaccine recipient.

Published by jbakerjrblog

Immunologist, former Army MD, former head of allergy and clinical immunology at University of Michigan, vaccine developer and opinionated guy.

7 thoughts on “If you think you have had COVID-19, get an antibody blood test before your vaccine. It may save you a shot!

  1. I have two questions: 1. do people who’ve had covid have less of a negative reaction to the vaccine? and 2. how long before the findings of these studies are likely to change the number of doses administered to someone who has had covid already?

    Liked by 1 person

  2. How and where can on a person get a covid antibody titer test? Does it require a MD prescriptilon; and can a patient ask their MD for one? What does the test cost, and will it usually be covered by health care insurance?


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