How WHO calculates excess deaths, and why India is questioning it

The World Health Organization (WHO) said that its new estimates show that the global “excess mortality” due to the COVID-19 pandemic between 1 January 2020 and 31 December 2021 was approximately 14.9 million (range 13.3 million to 16.6 million), and it put India’s excess deaths tally at over 4.7 million, the highest in the world and 10 times more than official figures.

After the WHO released its data on Thursday (May 5), the Indian government said it “strongly objects” to the use of mathematical models for projecting excess mortality estimates in view of the availability of authentic data.

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The WHO defines excess mortality as, “the mortality above what would be expected based on the non-crisis mortality rate in the population of interest”. Knowledge of the excess deaths not only paints a clearer picture of the pandemic, but can also aid in implementing public health initiatives, it added.

Most of the excess deaths (84%) are concentrated in South-East Asia, Europe, and the Americas. Some 68% of excess deaths are concentrated in just 10 countries globally. Middle-income countries account for 81% of the 14.9 million excess deaths (53% in lower-middle-income countries and 28% in upper-middle-income countries) over the 24-month period, with high-income and low-income countries each accounting for 15% and 4%, respectively, the WHO explained.

It further stated, “The estimates for a 24-month period (2020 and 2021) include a breakdown of excess mortality by age and sex. They confirm that the global death toll was higher for men than for women (57% male, 43% female) and higher among older adults. The absolute count of the excess deaths is affected by the population size. The number of excess deaths per 100,000 gives a more objective picture of the pandemic than reported COVID-19 mortality data.”

India’s excess deaths

According to the WHO report, India’s excess deaths for the 24-month period was 4,740,894. However, as per the Indian government’s official data, it is 4,81,000.

In the year 2020, India registered 4,74,806 deaths as per the Civil Registration System (CRS) report. However, as per the WHO’s estimates, India had 8,32,531 excess deaths in 2020, and more than 3.9 million including 2.3 million-plus in just two months (May and June) in 2021.

According to an IndiaSpend report in June 2021, “Andhra Pradesh, Bihar, Kerala, Madhya Pradesh and Tamil Nadu saw over 460,000 excess deaths in the first five months of 2021, compared to a typical year. Yet the official Covid-19 death toll for these states in this period, which covers the peak second-wave months of the pandemic in India, accounts for just 6% of these excess deaths.”

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A spate of deaths from “fever” and “unknown causes” tore through rural India in April and May, coinciding with India’s second Covid-19 wave, new official data show, IndiaSpend’s report in July 2021 said.

The National Health Mission’s (NHM) Health Management Information System (HMIS shows nearly 300,000 more deaths in May 2021 compared to May 2019, which is more than 2.5 times India’s official Covid-19 death count (120,072) for the same period, it added.

How does WHO calculate excess deaths?

The WHO said, “Excess mortality is calculated as the difference between the number of deaths that have occurred and the number that would be expected in the absence of the pandemic based on data from earlier years.

“Excess mortality includes deaths associated with COVID-19 directly (due to the disease) or indirectly (due to the pandemic’s impact on health systems and society). Deaths linked indirectly to COVID-19 are attributable to other health conditions for which people were unable to access prevention and treatment because health systems were overburdened by the pandemic. The estimated number of excess deaths can be influenced also by deaths averted during the pandemic due to lower risks of certain events, like motor-vehicle accidents or occupational injuries.”

WHO’s methodology

The harmonised methods for excess mortality have been developed in collaboration with the United Nations Department of Economic and Social Affairs (UN DESA), and in accordance with the WHO Regulations for Scientific and Advisory Groups, the WHO said.

The WHO convened a Technical Advisory Group (TAG) on COVID-19 Mortality Assessment to develop the methodology. The COVID TAG is comprised of leading demographers, epidemiologists, data and social scientists and statisticians from a range of backgrounds and geographies.

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While aggregate COVID-19 case and death numbers are being reported to WHO, they do not always provide a complete picture of the health burden attributable to COVID-19. In general, reported death numbers underestimate the number of lives lost due to the pandemic, there are several reasons for this. They miss those who died without testing, they are contingent on the country correctly defining COVID as the cause-of-death and they miss the increases in other deaths that are related to the pandemic leading to overwhelmed health systems or patients avoiding care, it said.

Method for India’s count

The WHO used the “Subnational Data Model” for India and a few other countries.

“The exercise of determining excess deaths for all countries is non-trivial because the required all-cause mortality (ACM) counts are currently unavailable for many country/month combinations. Routine mortality data is often received by the WHO a year or more after the year of death. Excess mortality cannot be directly measured for all countries due to many not having the required ACM data,” the WHO said in its report.

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The WHO usually receives routine mortality data on an annual basis in the year after the year of death or perhaps after an even greater lag. Civil registration and vital statistics (CRVS) systems differ greatly across countries with varying timelines and quality control measures for compiling unit record cause-of-death numbers into aggregates identified by cause, age, sex, place, and period of death.

“For a small number of countries for which national ACM data are not available (e.g., Argentina, India, Indonesia and Turkey) we instead have ACM data from subregions, with the number of regions with data potentially changing over time. India has data from up to 17 states (out of 26) over the pandemic period, but this number varies by month,” the report said.

For India, the WHO said it used a variety of sources. “We consider the most complex subnational scenario in which the number of regions with monthly data varies by month, using India as an example. For India, we use a variety of sources for registered number of deaths at the state and Union territory level. The information was either reported directly by the states through official reports and automatic vital registration, or by journalists who obtained death registration information through Right To Information requests.”

India’s strong reaction

The Ministry of Health and Family Welfare rejecting the WHO’s data and said, “India has been consistently objecting to the methodology adopted by WHO to project excess mortality estimates based on mathematical models. Despite India’s objection to the process, methodology and outcome of this modelling exercise, WHO has released the excess mortality estimates without adequately addressing India’s concerns. India had also informed WHO that in view of the availability of authentic data published through the Civil Registration System (CRS) by the Registrar General of India (RGI), mathematical models should not be used for projecting excess mortality numbers for India.”

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“India had pointed out the inconsistencies in the criteria and assumption used by WHO to classify Countries into Tier I and II as well as questioned the very basis for placing India into Tier II countries (for which a mathematical modelling estimate is used). India had also underlined the fact that given the accuracy of the Mortality Data collected through an effective and robust statutory system, India doesn’t deserve to be placed in Tier II countries. WHO till date has not responded to India’s contention,” it added.

The ministry questioned the “validity and robustness” of the WHO’s models.

“India has consistently questioned WHO’s own admission that data in respect of 17 Indian states was obtained from some websites and media reports and was used in their mathematical model. This reflects a statistically unsound and scientifically questionable methodology of data collection for making excess mortality projections in case of India. Throughout the process of dialogue, engagement and communication with WHO, WHO has projected different excess mortality figures for India citing multiple models, which itself raises questions on the validity and robustness of the models used.

“India objected to the use of Global Health Estimates (GHE) 2019 in one of the models used by WHO for calculating excess mortality estimates for India. GHE itself is an estimate. Therefore, a modelling approach which provides mortality estimates on the basis of another estimate, while totally disregarding the actual data available within the Country exhibits lack of academic rigour.

“The data released by the Civil Registration System (CRS) report-2020 under the aegis of the office of Registrar General of India (RGI) was shared with WHO for preparation of excess mortality report. Despite communicating this data to WHO for supporting their publication, WHO for reasons best known to them conveniently chose to ignore the available data submitted by India and published the excess mortality estimates for which the methodology, source of data, and the outcomes has been consistently questioned by India.”

Excess #COVID Mortality Estimates by @WHO: A rejoinder#India strongly objects to use of mathematical models for projecting excess mortality estimates in view of availability of authentic datahttps://t.co/u51mfvzH6t pic.twitter.com/OHP6e32W6y

— Ministry of Health (@MoHFW_INDIA) May 5, 2022

Dr NK Arora, chief of India’s Covid Working Group told NDTV on Friday that while there can be a 10-20% discrepancy, India’s robust and accurate death registration system (CRS) ensures that a majority of virus-related deaths are covered. He called the report “preposterous and untenable”.

“In 2018, around 85-88% of deaths were covered. In 2020, 98-99% of the deaths were covered. In 2018 and 2019, seven lakh deaths additional took place. Do we say that all were Covid? Out of the excess 4.6 lakh, 1.45 were the reported deaths. Those three lakh deaths took place due to other reasons. Even if we say 4 lakh deaths were extra, still it does not fit into the WHO estimates,” he told the TV channel.