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Which booster would you choose?

Question: If you were to choose which booster to get, which one would you choose?

Answer: Based on what we currently know, I think we can say a few things with confidence:

  1. If you meet booster requirements, it’s best to get boosted with what is available.  All three vaccines available in the US will improve your immunity and CDC recommendations allow for mix and match boosting.
  2. If you started with J&J, it’s preferable to get boosted with an mRNA vaccine (Pfizer or Moderna). Recent research indicates that antibodIes are much higher after boosting with mRNA vaccine as compared with boosting with J&J. And when it comes to infection prevention, research out of Sweden looking at Astra-Zeneca (same vaccine type as J&J, viral vector-type), found that vaccine effectiveness against symptomatic infection was much higher after boosting with mRNA-type vaccine as compared with boosting with viral-vector type vaccine.  
  3. If you started with Pfizer or Moderna, it’s probably best to stick with Pfizer or Moderna, but less clear whether it’s beneficial to mix and match between them. A few factors come into play.  First, as mentioned above, boosting with mRNA vaccine produces higher antibody response, which is why it’s probably best to stick with mRNA.  Second, if you tolerated your initial two doses well, you might want to keep with what you know. And third, some initial data showed that Moderna booster might produce more antibodies than Pfizer booster, but that data was based on a higher boosting dose of Moderna than is currently authorized.  As a reminder, each primary series of Moderna is dosed at 0.5mL, but the booster is dosed at 0.25mL.  Meanwhile, each primary series and booster of Pfizer is dosed at 0.3mL.  Some scientists think that the amount of mRNA in each vaccine might impact the number of antibodies produced, as The Atlantic recently described.  As a reminder, we still don’t know what threshold of antibodies is the “best” and “most antibodies” isn’t always better than “many antibodies.”

Back to your question: My primary doses were Pfizer and I tolerated them well.  It’s likely that when it’s my turn to get boosted, I’ll stick with Pfizer.  That said, if it turns out that only Moderna is available/offered at the clinic, I’ll happily accept that too!