system
Given the following post, respond as if you're commenting on Reddit:
human
Since Covid-19 has different variants, will it be better if we get two doses of different vaccines?
gpt
That is not the way the mRNA vaccines were designed to work.  They are designed to give you a training dose of the antigen and then the immune system kicks in more fully on the second dose.

There has been little to no testing done of the efficacy of mixing doses of different vaccines, though that is in progress.

Some of the labs are already working on Covid-19 booster shots that will add immunity to more variants; the existing vaccines were developed before we started finding all the worrisome variants.