I've been sent a link to a study that gives the data on risk/benefit ratio of boosters, in New Zealand:
https://econpapers.repec.org/paper/waieconwp/22_2f11.htm?utm_source=substack&utm_medium=email
As shown in that 'Peak Prosperity' video, the excess deaths during primary and secondary vaccination don't seem to be much more than expected for the winter period. Excess deaths for the booster period however, seem significantly high, given it was summer time.
You also need to factor in the impact of other measures on expected deaths - so NZ had pretty severe lock down measure in place until recently - in the absence of covid that would have markedly reduced mortality anyway as other transmissible (and sometimes fatal) diseases such as seasonal flu are suppressed. So for the first period you describe the baseline expected deaths would be lower than historically in a typical winter as we don't normally lock down etc.
But the other, important point, about the data is the lag between main vaccination and booster dates. We know that vaccine efficacy declines with time, hence the need for boosters. So the point about the summer data is that you need to take it in context of the booster roll-out. This is shown in Fig1B. So you will see that for the time period assess only about half of the people with earlier vaccination had had boosters. So there will be a considerable portion of the population will have declining vaccination efficacy from the initial vaccination programme, but not have had their boosters yet. Add in an understanding that NZ was beginning to significantly open up during the booster period, the prevalence of new, more transmissible variants, plus the legacy issue to delayed diagnosis of serious disease completely unrelated to covid and the data are completely expected.
None of this in any way negates the importance of the booster programme and without doubt had there been no booster programme, with everything else being the same, we'd have seen more excess deaths.