Have a look at the presentation to the FDA's VRBPAC on 2021-Oct-15:
K Lyke, et al., "DMID 21-0012 - Heterologous Platform Boost Study Mix and Match", FDA VRBPAC 2021-Oct-15 Materials, retrieved 2021-Oct-15.
(If you're curious about the how the whole meeting went down, I wrote a little summary.)
Slide 22 (page 23, because the FDA tacks on a header page) should help. It's a 3x3 array of the 3 original vaccines x 3 possible booster vaccines. It shows the factor by which antibody levels are boosted by each primer/booster combination (geometric mean titer fold induction).
For your case of a Moderna primer, the middle column is the one to look at: Moderna booster gave 10x boost, JnJ booster gave 6.2x, and Pfizer booster gave 11x. Given the error bars on that slide, Moderna and Pfizer are more or less indistinguishable (10x vs 11x), but both are likely better than JnJ.
In terms of absolute ab levels (the number shown in blue), a Moderna booster is probably a touch higher than Pfizer (3727 vs 2801), though I haven't used the error bars to calculate the statistical significance of that. Both are pretty good.
For me, the bottom line is that it looks like either Pfizer or Moderna are fine for somebody who's already gotten 2 doses of Moderna. The important thing is to get the booster if you need it; the choice of Pfizer or Moderna is over-optimization.
This is great, thanks!
Was wondering if you knew of any sources of how efficacy wanes over time (or persists) for two-doses of Moderna? I'm not actually sure if I do need a booster since I have no clue what baseline I'm working with.
Excellent data: thank you! Two things to keep in mind:
See also the limitations on page 33.
Excellent question, and I think a lot of us are wishing we had more data on this—unfortunately, there is very little data so far. But here's my take:
There's an argument to be made that absent strong reasons to do otherwise, it's best to follow standard practice (in this case, to get the same brand of booster as the original shots) simply because you'll be in a larger, better-studied cohort.
A couple of sources, such as they are:
“But something has really become clear: The mixing really is most impactful when you have a DNA/adenovirus vaccine first followed by the mRNA vaccine,” Gandhi said. WaPo
The study’s researchers warned against using the findings to conclude that any one combination of vaccines was better. The study “was not powered or designed to compare between groups,” said Dr. Kirsten E. Lyke, a professor at the University of Maryland School of Medicine, who presented the data. NYTimes
“But something has really become clear: The mixing really is most impactful when you have a DNA/adenovirus vaccine first followed by the mRNA vaccine,” Gandhi said. WaPo
This is definitely true in terms of antibody fold induction: JnJ followed by either Pfizer or Moderna have the highest fold induction ratios.
However, they're starting from a lower baseline, since JnJ doesn't induce such high ab levels to begin with. (Though it might be better at training T cells and memory B cells, and have longer persistence? It's kind of frustratingly complicated, to...
I read that the FDA has approved the Moderna booster shot as well as mix-and-match shots. I have two doses of Moderna and inclined to take a booster as Pfizer's booster showed 95.6% effectiveness in their Phase 3 trial.
Was wondering if any has substantial evidence or data on the Moderna booster shot and the mix-and-match shots? I'm eligible for it in a week and want to decide if I should get Moderna when it's available or mix with another booster.