The World Health Organization (WHO) on Thursday released a report estimating that between 13.3 million and 16.6 million deaths were linked to the coronavirus pandemic in its first two years. 

The long-awaited estimate is more than double the official death toll of 6 million where COVID-19 featured on death certificates either as the primary cause or a contributing factor.

Scientists tasked by the UN's health agency with calculating the COVID-19 death toll between January 2020 and the end of 2021 said the figure reflected deaths that were either caused directly by the virus or attributed to its impact on health systems, calculated by studying unexpected variations in so-called excess mortality. 

"These sobering data not only point to the impact of the pandemic but also to the need for all countries to invest in more resilient health systems that can sustain essential health services during crises, including stronger health information systems," WHO chief Tedros Adhanom Ghebreyesus said.

How is the pandemic death toll calculated? 

The WHO said the released figures are based on country-reported data and statistical modeling.

Excess mortality is calculated as the difference between the number of deaths that had occurred and the number that would have been expected in the absence of the COVID pandemic based on data from earlier years.

Accurate figures of coronavirus deaths have been problematic throughout the pandemic, as the numbers are only cautiously interpreted as a fraction of the devastation wrought by the virus. This is partly attributed to limited testing and differences in how countries count COVID-19 deaths, especially in places with patchy healthcare provision, and also to the difficulty of ascertaining how the pandemic might have impacted deaths caused by other things.

Epidemiologist Eric Feigl-Ding told DW that the World WHO estimate  is a very "conservative" one.

"I think that a lot of the developing countries do not have really good health, robust health care systems like the wealthier nations do, and they're easily swamped out," he said.

"Also, their health care systems don't track enough deaths that actually occurred. So the 15 million, I want to make clear, is the excess mortality above historical rates. This 15 million is a very conservative estimate."

Noting that the 15 million tally is substantially higher than the official confirmed number of deaths, he added that: "Economists estimate that between 2020 and 2021, there were actually 18 million. Actually now up to May 2022, there's 21 million."

Some governments have disputed WHO's methodology for calculating COVID deaths, resisting the idea that there were many more deaths than officially counted. 

Where are the highest excess mortality rates?

According to the WHO, 84% of the excess deaths were concentrated in Southeast Asia, Europe and the Americas. 

Some 10 countries alone accounted for 68% of all excess deaths.

Upper-middle-income nations accounted for 28% of the figure, lower-middle-income states 53% and low-income countries 4%.

Meanwhile, high-income countries accounted for 15% of the excess mortality rate. 

"This may seem like just a bean-counting exercise, but having these WHO numbers is so critical to understanding how we should combat future pandemics and continue to respond to this one," said Albert Ko, an infectious diseases specialist at the Yale School of Public Health who was not linked to the WHO research.

fb/msh (AFP, AP)