Could the global death toll be far higher than we thought?

For the past 18 months, hunkered down in his apartment in Tel Aviv, Ariel Karlinsky has scoured the internet for data that could help him calculate the true death toll of Covid-19.

- Laura Spinney

The 31-year-old economics student at the Hebrew University of Jerusalem had never worked on health matters before but he was troubled by rumours early in the pandemic that Israel was not experiencing higher than expected death rates.

“This was, of course, not true,” Karlinsky said. “Excess mortality was definitely there and it was definitely very visible.” He pulled up the numbers to prove it: Israel has a sophisticated vital registration system.

Other rumours followed. One was that countries that had put in place minimal containment measures or none at all were not experiencing significant excess mortality. Again it was not true – although getting hold of the data to prove it was trickier.

Karlinsky realised this was the case for most countries. Even those that routinely gathered excess-mortality data often did not publish it until at least a year later.

Through Twitter, Karlinsky met another researcher, the data scientist Dmitry Kobak, of the University of Tübingen in Germany. They agreed to collaborate. While Karlinsky searched for the numbers, Kobak took on the analysis.

The result is the World Mortality Dataset, which forms the basis of estimates of Covid mortality as published by the Economist, the Financial Times and others, and which gives the lie to the official global death toll of 4.8 million. The Economist, for example, puts the real number closer to 16 million.