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.