Saturday, November 27

Could the global number of Covid deaths be millions higher than previously thought? | Coronavirus


For the past 18 months, huddled in his Tel-Aviv apartment, Ariel Karlinsky has searched the web for data that could help him calculate the actual number of deaths from Covid-19.

The 31-year-old economics student at the Hebrew University of Jerusalem had never worked in health matters before, but was concerned by rumors early in the pandemic that Israel was not experiencing an increase above expected death rates and therefore, Covid was not serious.

“This, of course, was not true,” he said. “The excess mortality was definitely there and it was definitely very visible.” He pulled out the numbers to prove it, which was easy enough to do in Israel with his sophisticated vital registration system.

But other rumors followed. One was that countries that had not implemented minimal or no containment measures, such as Russia, were also not experiencing significant excess mortality. Again, it wasn’t true, but getting the data to prove it was more difficult.

Karlinsky realized that this was the case in most countries. Even those who routinely collected excess mortality data often didn’t publish it until at least a year later, meaning they weren’t aware of a sensitive indicator of the scale and progress of the pandemic, one that could inform your answer.

It became a challenge to collect that data for so many countries and as close to real time as possible.

Via Twitter he ran into another researcher, data scientist Dmitry Kobak from the University of Tübingen in Germany, who was trying the same thing, and they agreed to collaborate. As Karlinsky searched for the numbers, Kobak took up the analysis.

The result is the World Mortality Data Set, which forms the basis for Covid mortality estimates as published by the Economist, the Financial times and others, and which denies the official worldwide death toll of 4.8 million. The Economist, for example, brings the true figure 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 that resembles that seen in vaccine development and pathogen sequencing,” said epidemiologists Lone Simonsen, from the University of Roskilde in Denmark, and Cécile Viboud, from the National Institutes of Health in Denmark. USA wrote.

The death toll from a pandemic can be measured in several ways, all with advantages and disadvantages. The official number is derived from national reports of Covid deaths, but these are dependent on testing rates and are almost always underestimated.

Muslim worshipers in Casablanca, Morocco, follow Covid restrictions during prayers at the Hasan II mosque, one of the largest in Africa.
Muslim worshipers in Casablanca, Morocco, follow Covid restrictions during prayers at the Hasan II mosque, one of the largest in Africa. Photograph: Fadel Senna / AFP / Getty Images

“The official Covid death figures are simply not credible at all for a large group of countries,” said data journalist Sondre Ulvund Solstad, who leads The Economist’s pandemic tracking effort.

Excess mortality, defined as the increase in deaths from all causes above the expected level based on historical trends, does not depend on test rates. It is an old tool, which has been used to estimate the number of deaths from historical pandemics, especially when there was no diagnostic test for the disease in question, but until now it has always been calculated retrospectively.

Karlinsky and Kobak’s innovation is to collect and publish data during a pandemic, for a swath of the world, using established statistical techniques to fill in the gaps.

One disadvantage of excess mortality is that it is a compound. It captures not only deaths from Covid, but also deaths indirectly linked to the pandemic, such as those of cancer patients who were unable to receive timely treatment or victims of domestic abuse during lockdowns, without telling you much about the relative contributions of each.

However, by comparing the timing of excess mortality peaks and blockages, Karlinsky and Kobak have shown that, in the case of Covid, excess mortality primarily reflects deaths from the disease.

Calculating excess mortality can also generate some strange results. In June, for example, reported in eLife magazine that excess mortality had been negative in countries such as Finland, South Korea and Australia, which means that fewer people had died there than in previous years, because the control of the pandemic in those countries had been excellent and they had also eliminated almost completely flu in 2020. In such cases, according to Simonsen and Viboud, official Covid deaths are a more accurate indicator of the number of victims of the pandemic.

The world mortality dataset contains information on more than 100 countries. Among the missing are most African and Asian countries, including some of the most populous in the world and, judging by news reports and other sources, the hardest hit. India, for example, does not routinely publish national vital data, yet some researchers estimate his death toll from Covid could reach 4 million.

A health official receives his first dose of the Covid vaccine at a hospital in Abuja, Nigeria.
A health official receives his first dose of the Covid vaccine at a hospital in Abuja, Nigeria. Photograph: Afolabi Sotunde / Reuters

Karlinsky and Kobak have drawn sub-national data sources from these data-poor countries, or have been provided by journalists, academics, and dissidents who live there, and have applied various extrapolation techniques to produce national estimates.

Or they have projected from neighboring countries where data is available, adjusting for factors such as population density, Covid testing strategy, and freedom of the press.

The uncertainty in the data is the reason that Karlinsky and Kobak have avoided estimating the global number of deaths, but say that the excess of deaths nationwide is 1.4 times higher than the reported Covid deaths, on average, what that would give an approximate global count of 6.7 million.

Solstad’s model put the number between 9.9 million and 18.5 million, a range that Simonsen considered reasonable.

To put these numbers in historical perspective, she and Viboud took estimates of excess mortality for past pandemics and adjusted them for the world population in 2020.

This resulted in a death toll from the four previous flu pandemics, if they had occurred now, of 75 million (1918), 3.1 million (1957), 2.2 million (1968), and 0.4 million (2009 ).

Covid is the deadliest pandemic in a century, they conclude, “but nowhere near the death toll from the 1918 pandemic.”

The new dataset shows that countries that made international headlines for having severe outbreaks, such as Italy, Spain and the United Kingdom, have not actually been hit the hardest.

The worst include Mexico and Bolivia, but also some Eastern European countries, which have experienced a more than 50% increase in mortality. The most affected, Peru, has registered an increase of 150%.

The dataset becomes more accurate over time because some data is filtered with a time delay. Some countries asked their national statistical offices to speed up the collection and publication of vital data in early 2020, but others were unable or unwilling to publish it. Turkey was expected to release monthly vital data for 2020 early this summer. Does not have.

Women with masks shop at a local market in Istanbul, Turkey
A market in Istanbul. Turkey has yet to release vital monthly coronavirus data for 2020. Photograph: Dilara Senkaya / Reuters

“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, the excess mortality could shine a revealing sidelight on government transparency. If the official Covid deaths were lower than the excess deaths but followed roughly the same trajectory, it is likely that the country simply lacked vital registration or testing capacity.

Solstad believes that excess mortality should be continuously tracked in the future, because it would provide a better understanding of all kinds of crises, including wars and famines. “It’s a pretty objective measure of things that go 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 want to do this. In February, the World Health Organization took the first step in harnessing excess mortality as a surveillance tool, when it established a expert committee to assess mortality from Covid.

Governments could act more quickly 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, he added, was that in many countries “a lot happened.”


www.theguardian.com

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