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.
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.
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.
Pandemic Pondering 
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?
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Not clear what the reactivity is, but theoretically could meake the first dose feel like the second; more intense. Not clear when the recommendations will change.
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What antibody level is high enough to avoid getting the 2nd vaccine.? Thank you.
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Any positive antibody test would work. Titer is not important.
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Now if we could just get Public Health officials at CDC, Whitehouse and States to follow the science…
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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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Easiest to ask MD, but now more commonly available at Pharmacies and clinics.
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