On Friday, I posted charts showing that excess mortality is negatively related to elderly vaccination in both Europe and the U.S. In other words: European countries and U.S. states with higher elderly vaccination rates have seen less excess mortality since the pandemic began.
I argued, therefore, that focussed protection culminating in voluntary vaccination of high-risk groups was the right strategy all along – which is what the Great Barrington Declaration called for.
One objection to my aggregate-level analysis is that the relationships between excess mortality and elderly vaccination could be confounded by other variables. In fact, the relationship in the European sample was much weaker when controlling for healthcare spending – which is evidence of confounding.
On the other hand, with a sample size of only 30 countries, it is not always possible to disentangle the effects of correlated predictors. And in the larger American sample, the relationship remained strong when controlling for healthcare spending.
Another way to test whether elderly vaccination made a difference is to check which is a stronger predictor of excess mortality in 2021: excess mortality in 2020, or the elderly vaccination rate. (The vaccines became available at the end of 2020, so will not have had an impact until 2021).
It’s possible that some places are simply better at preventing Covid deaths – whether because their populations are healthier, they provide higher quality healthcare, or some combination of factors. If so, you’d expect to see a strong relationship between excess mortality in 2020 and excess mortality in 2021 – even when controlling for the elderly vaccination rate.
On the other hand, if elderly vaccination is what matters, you’d expect to see a strong relationship between the elderly vaccination rate and excess mortality in 2021 – even when controlling for excess mortality in 2020.
To put it another way: if some places are simply better at preventing Covid deaths than others, excess mortality in 2020 should be a stronger predictor of excess mortality in 2021; but if elderly vaccination matters is what matters, the elderly vaccination rate should be stronger predictor of excess mortality in 2021.
I ran the numbers, and found that in both samples the elderly vaccination rate was a stronger predictor of excess mortality in 2021. So the places that had lowest excess mortality in 2021 weren’t necessarily the places that had lowest excess mortality in 2020; rather, they were the places that had the highest elderly vaccination rates.
This constitutes additional evidence that vaccinating the elderly saved lives. All the caveats in my original post still apply.