The "two (of many) statistically significant studies" you provided are worthless as they are even before when delta wasn't even around. Relying on such outdated studies to make your point is very misleading when my comment specifically said "delta":
I take it that you do agree with conclusions of the parent, that vaccines are indeed effective against Covid, but that effectiveness is mediated by viral strains/mutations such as delta?
https://news.ycombinator.com/item?id=34721451