Early indicators from Israel, which is ahead of the booster curve:
> Israel Is Preparing for Possible Fourth Covid Vaccine Dose
> “We don’t know when it will happen; I hope very much that it won’t be within six months, like this time, and that the third dose will last for longer,” Health Ministry Director General Nachman Ash said in an interview with Radio 103FM.
> Israel, which has mainly used the Pfizer Inc.-BioNTech SE vaccine, has so far inoculated about 2.8 million people with a third dose after beginning a drive to administer booster shots in August. Health officials have said the effects of the initial Covid-19 shots weaken five months after inoculation, making boosters necessary.
https://www.bloomberg.com/news/articles/2021-09-12/israel-pr...
Anyway, I’m rambling. In a nutshell, they shouldn’t be thought of as the same technology because well, they’re not.
IPV , OPV, the DTaP vaccines, the pneumococcal conjugate vaccine, and measles are all different technologies. They’re all biologics, though.
The booster being the same formula does not, in any respect, mean that. There are quite a few vaccines that are given in multiple similar or identical doses and provide stronger and longer lasting protection after the later sides.
My guess (purely a guess) is that the actual problem with the Pfizer vaccine is that the sides are too close together. The Moderna doses are spaced farther apart and (preliminary, unreviewed) results suggest that it works just fine even six months after the second dose.
I would not be at all surprised if a booster dose of either mRNA vaccine after six months gives essentially lifelong protection. I also would not be surprised if it didn’t.