Mortality associated with Covid-19 would have been largely underestimated, according to a study – rts.ch

The Covid-19 pandemic would have caused more than 18 million deaths worldwide between early 2020 and late 2021, according to a study published Friday in The Lancet magazine. This estimate corresponds to more than three times the official balance.

“Official statistics on Covid-19 deaths provide only a partial picture of the true death toll” linked to the pandemic in the world, researchers from the University of Washington in Seattle (USA) observe. Covid-19 is potentially one of the leading causes of death in 2020 and 2021, they say.

If the official figure announces 5.94 million deaths worldwide between 1 January 2020 and 31 December 2021, various works have considered it to be greatly underestimated and have tried to better assess the overall assessment of the pandemic.

Study based on excess mortality

The most recent study to date, the one published in Lancet recalculates the number of deaths associated with Covid-19 to 18.2 million during this period, more than three times the official balance sheet, based on calculations based on excess mortality. An expression that corresponds to the difference between the number of people who died, regardless of the cause of their death, and the number of expected deaths based on previous data.

In addition to a mortality database, the authors of the study have in particular built several models to predict the expected mortality in the absence of Covid-19, among other things to compensate for the lack of complete and solid data in several countries.

“Of the 12.3 million additional deaths, compared to the recorded Covid-19 deaths, a significant portion are likely to be due to infection with SARS-CoV-2,” they estimate.

The difference between the excess mortality and the recorded Covid-19 deaths can be explained by an underdiagnosis of coronavirus infections and / or by deaths from other diseases that are higher than expected under the effect of behavioral changes or less access to care because of the pandemic, according to the researchers.

Asked in the CQFD program, Antoine Flahault, epidemiologist and director of the Department of Global Health at the University of Geneva (UNIGE), specifies that the article assesses “the excess mortality of the pandemic”, ie. not just the deaths directly due to viruses. It is a kind of “global sum, which is thus calculated”.

Several affected regions

The Andean countries of Latin America, Eastern and Central Europe, sub-Saharan Africa, showed the highest excess mortality in 2020-2021.

Of the countries hardest hit by the pandemic, Bolivia had the highest excess mortality. Conversely, excess mortality in countries such as Australia and New Zealand seemed to be below the usual level.

With 489,000 deaths due to the pandemic, India would be particularly far from the target. It would have actually lost nearly four million of its inhabitants because of Covid, according to the study.

In Switzerland, nearly 13,000 deaths have been linked to Covid-19 identified by FOPH since the start of the pandemic. The authors of the research would estimate the actual number between 14,000 and 17,000 dead.

Further studies are needed

The researchers recognize some limitations in their study. They consider further work necessary to measure excess mortality directly due to Covid-19.

Among various surveys, the weekly The Economist estimated the total number of pandemics at 17 million deaths worldwide in a work published in mid-November, and in particular based on a database of two researchers.

The World Health Organization has so far estimated, taking into account the excess mortality directly and indirectly associated with Covid-19, that the pandemic may be two to three times higher than the official figure.

But can we then rely on these numbers? “Yes and no,” explains Antoine Flahault. The researcher recalls that some countries have census systems that make it possible to know the number of births and deaths within it.

“But there are countries like Tanzania or Liberia that do not have vital records. When they do not have the data, researchers try to retrieve them from other studies such as research into seroprevalence, demography, mortality. Then we make an extrapolation that may be questionable. “the case of Covid, because we know there is a great deal of heterogeneity. For example, Italy makes the difference between the south of the country, Puglia and the Milan region,” Antoine Flahault said.

“The best estimator”

After all, the UNIGE scientist believes that excess mortality is “probably the best estimate of the severity of an epidemic phenomenon”.

“We have been doing this for a long time for influenza. In addition, the excess mortality estimated when there is a seasonal influenza epidemic that passes is much higher than the mortality rate reported by doctors on death certificates to the Office of Federal Public Health.” , he explains at RTS.

And to continue: “There is therefore a very large discrepancy because we are not testing for influenza, as we tested for Covid-19. This excess mortality in developed countries is lower between what is declared and the excess mortality, but it does exist.”

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