Covid-19: Why some nations have deadlier outbreaks with the same vaccines

 A number of countries -- mostly developing economies with less capable healthcare systems -- relied on Chinese or Russian vaccines that have proven less effective than the mRNA shots used in the US

It’s one of the great puzzles of the pandemic. Most developed economies are now highly vaccinated with some of the most effective shots on offer, so why are the latest Covid-19 outbreaks more deadly in some places than in others?

While it’s clear vaccines led to a drop in fatalities during the most recent delta variant-driven waves compared with earlier bouts with the virus, some countries saw deaths fall to a greater degree than others, an outcome scientists still don’t have answers for.

Countries like Germany, Denmark and the U.K. have seen Covid deaths fall to roughly a tenth of previous peaks, according to Bloomberg calculations using data compiled by Johns Hopkins University. In Israel, Greece and the U.S., fatalities fell but remained more than half of the previous peaks.

A number of countries -- mostly developing economies with less capable healthcare systems -- relied on Chinese or Russian vaccines that have proven less effective than the mRNA shots used in the U.S. and throughout Europe. Those places have experienced an increase in both cases and deaths since July, when delta started wreaking havoc globally,compared to outbreaks that occurred before widespread vaccination was an option.

We lensed in on the economies that have vaccinated more than 55% of their populations and relied on a mix of western shots from Pfizer Inc.-BioNTech SE to AstraZeneca Plc, which have effectiveness rates of about 60 to 90% against symptomatic cases of the delta variant.

One thing is clear: it’s not just the type of shots nor the extent of vaccination that counts in bringing down the death toll.