I guess I'd be worried about the rate of breakthrough infections amongst vaccinated people in Israel, the first good data we have (the reason for booster shots). That same data showed that natural immunity was much better. [0]

It may be the case where countries like New Zealand can only delay, but not prevent, this moving through their population at some point.

[0] https://www.israelnationalnews.com/News/News.aspx/309762