Estimating the all-cause excess mortalities due to COVID-19

In a recent study published in the Journal of Development Economics, researchers estimated all-cause excess death rates due to the coronavirus disease 2019 (COVID-19) pandemic.

Due to a lack of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic testing, official figures on COVID-19 deaths undercount deaths. Death registries are utilized in developed nations to determine the excess deaths caused by COVID-19 during the pandemic. However, before the pandemic, only a few developing nations had complete death registries, and the pandemic severely strained administrative capabilities.

About the study

In the present study, researchers employed a representative household panel survey to estimate the excess deaths from all causes in India during the COVID-19 pandemic.

The main source of data for the study was the Consumer Pyramids Household Survey (CPHS), which was a sizable and representative survey of Indian households conducted by the Center for Monitoring the Indian Economy. A collection of comparable districts inside a state is known as a homogenous region. Every round, which consists of four month periods, sample homes were visited. However, each month, a subsample of households typical of the entire country is sampled. The most recent data we could obtain for CPHS, which began in January 2014, were from April 2022. The team began the research using data from 2015.

The CPHS maintained a thorough list of all households even though its primary objective was to estimate household economic parameters. If a household had experienced a death since the last time it was surveyed, which was normally four months ago, it was noted as such on the roster. The 2011 Indian Census defined a rural region as a village, and the CPHS also provided information related to the demographics and income corresponding to each household member, as well as the household's district-level location. The team investigated the variation in death rates using this data.

In two steps, the team estimated the excess deaths. Using information from before the pandemic, the forecast monthly mortality rates were estimated in the absence of the pandemic. The average number of mortalities during a pre-pandemic baseline period or the trend in those deaths throughout the baseline period were used to calculate these anticipated mortality rates. Furthermore, the team estimated the difference between an individual indicator for fatality and the anticipated individual death rate during the pandemic.

Results

The death rate appeared to have increased during the COVID-19 pandemic, according to CPHS raw data that was aggregated on the national level. Death rates increased significantly during the first wave, slightly less during the second wave, and barely during the third wave. However, the significant increase in wave one was partially attributable to homes that were left out of the poll during the lockdown reporting deaths afterward. The number of deaths in wave one was probably more evenly distributed. The slight relative increase in deaths observed in the official death figures was consistent with the small wave three rise.

During the national lockdown in April and May 2020, the death rate declined, but throughout the remaining months of the pandemic, it remained at or exceeded the 2019 average. When the pandemic strikes, there are four peaks. When the lockdown was lifted in June 2020, there was one spike. The team noted that first wave's peak occurred in September 2020, while that of wave two occurred between March and May 2021, and of wave three occurred in February 2022. Except for the February 2022 peak, all increases were significantly higher than the adjacent months and all 2019 months except one. Even the highest peak of 2019 was lower than all the spikes in the first and second waves.

The average death rate estimated was 0.787%, which was not significantly different from the calculated global disease burden. However, the excess death rate during the epidemic was 0.399%, which showed a considerable rise of more than 50%. When the team considered the 2019 level as the baseline, the baseline death rate increased to a high of 1.038%. The estimate of the pandemic's excess mortality rate was 0.147%, which was comparatively higher but consistent with the relative rise in excess fatalities in the US.

When the team divided the COVID-19 pandemic into waves, a general pattern was observed across baselines wherein the excess fatalities in wave two were almost twice as high as those in wave one, and excess deaths in wave three were on the decline. The outcome of wave two was predictable as wave two with the SARS-CoV-2 delta variant affected India more severely than wave one with SARS-CoV-2 wild-type infections. Although wave one appeared to linger longer, the second wave had a high enough peak to make up for the shorter duration.

Overall, the study provided novel estimates of excess deaths due to COVID-19 in India, thus enriching COVID-19-related research in the country.

Written by

Bhavana Kunkalikar

Bhavana Kunkalikar is a medical writer based in Goa, India. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. Her educational background allowed her to foster an interest in anatomical and physiological sciences. Her college project work based on ‘The manifestations and causes of sickle cell anemia’ formed the stepping stone to a life-long fascination with human pathophysiology.