Unknown. Mark Zuckerberg was right about that one.

I suspect China may have a "part two" to this virus already developed that will exterminate people who have already been infected and the various mRNA shots are a desperate measure to mitigate that--even if it injures or kills people. We can't tell the public. We can't reveal that we know what they are doing. So we just do our best to save as many people as possible, even without knowing all the details.