As others (including @florian_krammer@Daltmann10 etc) have shown, folks who have recovered from COVID only need 1 dose to get peak antibody responses to full-length spike protein and the RBD. People who are SARS-CoV-2 naive need 2 doses for optimal responses
Similar data for neutralizing ability against wild-type (D614G) strain & the B.1.351 (S African) variant
2nd dose especially important in people w/o prev infx... 50/50 on neutralizing antibody against D614G & very little against B.1.351 after dose 1. Great response after dose 2
mRNA vax induced robust memory B cell responses to full-length spike & RBD
1 dose = peak response in recovered folks. Continued improvement w/ 2nd dose in the SARS-CoV-2 naive group
In SARS-CoV-2 naive individuals, these memory cells continue to improve over time. Increase in % of IgG+ cells and also a focusing of the response on the RBD
Recovered individuals again get little qualitative benefit to their B cell response from 2nd dose
Another question we get a lot: how does age affect vaccine response?
There is a slight negative trend btw/ age and antibodies
We do see a stronger association btw/ age and memory B cells post-boost, but everyone is still over baseline so something to keep an eye on longer-term
What about side effects? Turns out you do get some benefit to your antibody response if you had systemic symptoms (i.e fever, chills). No pain, no gain...
But side effects do not impact the generation of memory cells. And even w/o side effects, everybody had a great response
Relationships btw these different measures of immunity: do antibodies predict memory (or vice versa)?
Turns out that just measuring post-boost antibodies doesn't tell us much about memory. BUT baseline memory does predict antibody recall upon re-exposure in recovered folks
So what are the take-home points:
1) Probably ok to delay or skip 2nd dose in individuals who previously had COVID
2) 2nd dose important for the quality of immune response in previously uninfected individuals
3) Some association of age & side-effects w/ vaccine response
Our study on #mRNA vax in #SARSCoV2 naive/recovered individuals is up on medRxiv! Massive team effort btw/ @EJohnWherry lab + others @Penn_IFI to profile both antibodies & antigen-specific memory B cells following 1st/2nd doses. bit.ly/3rlfhwO. Full tweetorial below 💉🧵
1) Consistent w/ what others (e.g. @florian_krammer) have shown: COVID-experienced folks don’t have an increase in antibodies after 2nd dose… clear benefit for people who are COVID-naive
2) We also find the same pattern for antigen-specific memory B cells… COVID-experienced folks have an increase in spike+ and RBD+ memory cells after the first dose, but then plateau w/ no increase in frequency or class switching after the second dose