One of the authors of a research paper on Covid-19 mortality in 2020 on Sunday defended its findings after the Union health ministry dismissed the study suggesting the possibility of excess deaths as a “gross and misleading overestimate”.

The paper published on Friday in the science journal Science Advances compared the number of deaths in 2020 to that in 2019, using data from the National Family Health Survey.

The study said that India had 1.19 million excess deaths in 2020, the first year of the Covid-19 pandemic, compared to 2019. The government had recorded 148,738 deaths in 2020 in the country due to the disease caused by the novel coronavirus.

On Saturday, the Union Ministry of Health and Family Welfare said that the findings of the research paper on life expectancy during the Covid-19 pandemic in India in 2020 are “based on untenable and unacceptable estimates”.

The methodology adopted by the study had “critical flaws”, the ministry said in a press release. The government questioned the sample selection from the National Family Health Survey data and claimed that there is a possibility of reporting biases in the study. It also dismissed the criticism in the research paper about the government’s system for registering deaths and the Sample Registration Survey.

“The most important flaw is that the authors have taken a subset of households included in the NFHS survey between January and April 2021, compared mortality in these households in 2020 with 2019, and extrapolated the results to the entire country,” the ministry said.

It added that the National Family Health Survey sample is representative of the country only when it is considered in its entirety. “The 23% of households included in this analysis from part of 14 states cannot be considered representative of the country,” it said.

Aashish Gupta, the co-author of the study, however, said taking 23% of the households of the National Family Health Survey sample as a sub-sample was a “feature of the study, not a criticism”.

“In the study, we have compared the sub-sample to the full sample of the NFHS, and we have shown that both the samples show similar characteristics across sex, social groups, wealth and gender,” Gupta told Scroll. “So, it is unfair for the government to just say that it is a sub-sample. So what if it is a sub-sample, is it biased?”

On including responses from only 14 states, Gupta said that a sero-survey, which studies antibody levels against a virus, conducted in December 2020 had shown that the seroprevalence is the same, 24% to 26%, as had been noticed in the sub-sample of the research.

Further, he said that the excess mortality estimate based on the sub-sample in the study comes to about 330,000.

“So even the excess mortality only in the sub-sample is higher than Covid deaths [in 2020],” the researcher said. “This means that the all-India numbers will be higher than that.”

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The government also said that it was erroneous on part of the researchers to argue that there was a need for such an analysis because the vital registration system in low- and middle-income countries, including India, is weak.

“This is far from being correct,” the ministry stated. “The Civil Registration System (CRS) in India is highly robust and captures over 99% of deaths.”

The reporting of deaths has constantly increased from 75% in 2015 to over 99% in 2020, the ministry said. This increased by 474,000 in 2020 compared to 2019, the ministry added. A similar increase in death registration had been observed in 2018 and 2019 over the previous years.

The health ministry also asserted that not all excess deaths in a year in the Civil Registration System were attributable to Covid-19. “Excess number is also due to an increasing trend of death registration in CRS (it was 92% in 2019) and a larger population base in the succeeding year,” it said.

Gupta, however, said that the explanation given by the government for excess deaths in 2020 does not add up.

“The NFHS is the most recent estimate of death registration completion in India and that estimate is 71%, this is the government’s own data,” Gupta said. “So, how can the Civil Registration System capture 99% deaths? The government’s claim has little empirical basis.”

The ministry claimed that the nature of the estimate published by the researchers being erroneous is further established by the fact that the study had ignored the government’s Sample Registration System data from 2020 that “shows very little, if any, excess mortality compared with 2019 data”.

Citing an October 2022 report in The Hindu, Gupta alleged that the 2020 Sample Registration System survey is “full of inaccuracies”

The ministry further criticised the study for claiming that the excess mortality was greater among women and younger age groups. It said that data on deaths caused by Covid-19 had shown that the mortality was instead higher among men and older age groups.

Gupta, however, claimed that the government’s data was biased. “Since there is undercounting of female deaths due to gender-bias in the Indian society, the deaths among males are reported more,” he said.

(This article has been updated to more accurately reflect the researcher’s views.)