Could the worldwide Covid death toll be millions higher than expected? | Coronavirus
For 18 months, crouching in his Tel Aviv apartment, Ariel Karlinsky has scoured the web in search of data that could help him calculate the true death toll from Covid-19.
The 31-year-old economics student at the Hebrew University of Jerusalem had never worked on health issues before, but was troubled by rumors at the start of the pandemic that Israel was not experiencing an increase in the- above expected death rates, and therefore Covid was not serious.
“That was of course not true,” he said. “The excess mortality was there and it was definitely very visible. He pulled the numbers to prove it, which was pretty easy to do in Israel with his civil registration system.
But other rumors followed. One was that countries that had no or minimum containment measures in place, such as Russia, also did not experience significant excess mortality. Again, that wasn’t true – but getting the data to prove it was trickier.
Karlinsky realized that this was the case for most countries. Even those who regularly collected excess mortality data often did not release it until at least a year later, meaning they were unaware of a sensitive indicator of the scale and progress of the pandemic. – an indicator that could shed light on their response.
It has become a challenge to bring this data together for as many countries and as close to real time as possible.
Through Twitter, he met another researcher, data scientist Dmitry Kobak from the University of Tübingen in Germany, who was trying the same thing, and they agreed to collaborate. While Karlinsky researched the numbers, Kobak did the analysis.
The result is the Global Mortality Data Set, which forms the basis of the Covid mortality estimates as published by the Economist, the Financial Time and others, and which belies the official global death toll 4.8 million. The Economist, for example, puts the real number closer to 16 million.
Those who measure the impact of public health disasters have applauded the efforts of Karlinsky and Kobak. “This is a data revolution parallel to that observed in vaccine development and pathogen sequencing,” epidemiologists Lone Simonsen, from Roskilde University in Denmark, and Cécile Viboud, from the National Institutes of Health from the United States, wrote.
The death toll from a pandemic can be measured in a number of ways, all of which have their pros and cons. The official number is derived from national reports on Covid deaths, but these depend on testing rates and are almost always underestimated.
“The official Covid death figures are just not credible at all for a large group of countries,” said data reporter Sondre Ulvund Solstad, who is leading The Economist’s pandemic monitoring effort.
Excess mortality, defined as the increase in deaths from all causes over the level expected based on historical trends, does not depend on screening rates. It is an old tool, having been used to estimate the death toll from historical pandemics – especially when there was no diagnostic test for the disease in question – but so far it has always been calculated retrospectively.
Karlinsky and Kobak’s innovation is to collect and publish data during a pandemic, for part of the world, using established statistical techniques to fill in the gaps.
One of the disadvantages of excess mortality is that it is composite. It captures not only Covid deaths but also deaths indirectly linked to the pandemic, such as those of cancer patients who were unable to get timely treatment or victims of domestic violence during lockdowns, without you. say a lot about the relative contributions of each.
By comparing the timing of excess mortality peaks and lockdowns, however, Karlinsky and Kobak showed that in the case of Covid, excess mortality primarily reflects deaths from the disease.
Calculating excess mortality can also generate strange results. In June, for example, they reported in eLife magazine that excess mortality had been negative in countries like Finland, South Korea and Australia – meaning fewer people had died there than in previous years – because control of the pandemic in those countries had been excellent and that they had also virtually eliminated the flu by 2020. In such cases, according to Simonsen and Viboud, official Covid deaths are a more accurate indicator of the pandemic’s toll.
The World Mortality Dataset contains information on more than 100 countries. Among those missing are most African countries and many Asian countries, including some of the most populous countries in the world and – judging from reports and other sources – the most affected. India, for example, does not routinely publish national vital data, but some researchers estimate its Covid death toll could reach 4 million.
Karlinsky and Kobak extracted subnational data sources from these data-poor countries – or were provided to them by journalists, academics, and dissidents living there – and applied various extrapolation techniques to produce national estimates.
Or they projected neighboring countries where data is available, adjusting for factors such as population density, Covid testing strategy, and press freedom.
Uncertainty in the data is why Karlinsky and Kobak avoided estimating the death toll worldwide, but they say excess deaths nationwide are on average 1.4 times higher than reported Covid deaths, which would give an approximate global tally of 6.7 million.
Solstad’s modeling put the number between 9.9 million and 18.5 million, a range Simonsen found reasonable.
To put these numbers in a historical perspective, she and Viboud took excess mortality estimates for previous pandemics and adjusted them for the global population in 2020.
This gave the death toll for the four previous influenza pandemics, if they had occurred now, of 75 million (1918), 3.1 million (1957), 2.2 million (1968) and 0.4 million (2009).
The Covid is the deadliest pandemic in a century, they conclude, “but has nothing to do with the death toll from the 1918 pandemic”.
The new data set shows that countries that have made international headlines for experiencing severe epidemics, such as Italy, Spain and the UK, have not been hit the hardest.
The worst are Mexico and Bolivia – but also some countries in Eastern Europe, which have seen a more than 50% increase in mortality. The most affected, Peru, recorded an increase of 150%.
The dataset becomes more precise over time because some data arrives with a time lag. Some countries have asked their national statistical offices to speed up the collection and publication of vital data in early 2020, but others have been unable or unwilling to publish them. Turkey was due to release monthly vital data for 2020 in early summer. He does not have.
“Turkey is a great example of a place where they have the numbers but they don’t publish them because they don’t want to explain the discrepancies,” Karlinsky said.
In fact, he said, excess mortality could open a revealing side window on government transparency. If official Covid deaths were lower than excess deaths but followed roughly the same trajectory, it was likely that the country simply lacked capacity for testing or civil registration.
Solstad believes excess mortality should be continuously monitored in the future, as this would provide a better understanding of all kinds of crises, including wars and famines. “It’s a pretty objective measure of things going wrong,” he said. Karlinsky agrees. When a heat wave hit Egypt in 2015, for example, state media reported 61 deaths; his estimate was closer to 20,000.
Some countries may not wish to do this. In February, the World Health Organization took the first step towards using excess mortality as a surveillance tool by setting up a expert committee to assess Covid-related mortality.
Governments could act faster and proportionately if they know that a crisis is imminent. They would also be better equipped to persuade the public of the need to do so. “Some people really believe that if we hadn’t done anything to stop this virus, not much would have happened,” Simonsen said. What the global mortality data set showed, she added, is that in many countries “a lot has happened.”