All-cause mortality during the COVID-19 pandemic in Chennai, India: an observational study

Joseph A Lewnard,Ayesha Mahmud,Tejas Narayan,Brian Wahl,T S Selvavinayagam,Chandra Mohan B,Ramanan Laxminarayan

doi:10.1016/s1473-3099(21)00746-5

Abstract

BackgroundIndia has been severely affected by the ongoing COVID-19 pandemic. However, due to shortcomings in disease surveillance, the burden of mortality associated with COVID-19 remains poorly understood. We aimed to assess changes in mortality during the pandemic in Chennai, Tamil Nadu, using data on all-cause mortality within the district.MethodsFor this observational study, we analysed comprehensive death registrations in Chennai, from Jan 1, 2016, to June 30, 2021. We estimated expected mortality without the effects of the COVID-19 pandemic by fitting models to observed mortality time series during the pre-pandemic period, with stratification by age and sex. Additionally, we considered three periods of interest: the first 4 weeks of India's first lockdown (March 24 to April 20, 2020), the 4-month period including the first wave of the pandemic in Chennai (May 1 to Aug 31, 2020), and the 4-month period including the second wave of the pandemic in Chennai (March 1 to June 30, 2021). We computed the difference between observed and expected mortality from March 1, 2020, to June 30, 2021, and compared pandemic-associated mortality across socioeconomically distinct communities (measured with use of 2011 census of India data) with regression analyses.FindingsBetween March 1, 2020, and June 30, 2021, 87 870 deaths were registered in areas of Chennai district represented by the 2011 census, exceeding expected deaths by 25 990 (95% uncertainty interval 25 640–26 360) or 5·18 (5·11–5·25) excess deaths per 1000 people. Stratified by age, excess deaths numbered 21·02 (20·54–21·49) excess deaths per 1000 people for individuals aged 60–69 years, 39·74 (38·73–40·69) for those aged 70–79 years, and 96·90 (93·35–100·16) for those aged 80 years or older. Neighbourhoods with lower socioeconomic status had 0·7% to 2·8% increases in pandemic-associated mortality per 1 SD increase in each measure of community disadvantage, due largely to a disproportionate increase in mortality within these neighbourhoods during the second wave. Conversely, differences in excess mortality across communities were not clearly associated with socioeconomic status measures during the first wave. For each increase by 1 SD in measures of community disadvantage, neighbourhoods had 3·6% to 8·6% lower pandemic-associated mortality during the first 4 weeks of India's country-wide lockdown, before widespread SARS-CoV-2 circulation was underway in Chennai. The greatest reductions in mortality during this early lockdown period were observed among men aged 20–29 years, with 58% (54–62) fewer deaths than expected from pre-pandemic trends.InterpretationMortality in Chennai increased substantially but heterogeneously during the COVID-19 pandemic, with the greatest burden concentrated in disadvantaged communities. Reported COVID-19 deaths greatly underestimated pandemic-associated mortality.FundingNational Institute of General Medical Sciences, Bill & Melinda Gates Foundation, National Science Foundation.TranslationFor the Hindi translation of the abstract see Supplementary Materials section.

Highlights

India is among the most severely affected countries in the ongoing COVID-19 pandemic, with over 458 000 deaths reported by Nov 1, 2021
Expect for large-scale studies addressing community-level predictors of variation in COVID-19 burden in Brazil and one study addressing differences in SARS-CoV-2 seroprevalence in slum and non-slum communities within Mumbai, we found no studies comparing the burden of COVID-19 across socioeconomically distinct communities within low-income and middle-income countries
Our analyses considered three specific periods of interest: first, the first 4 weeks of India’s country-wide lockdown (March 24 to April 20, 2020), before community transmission of SARS-CoV-2 was widespread in Chennai and surrounding areas;7 second, the 4-month period encompassing the first wave of the pandemic in Chennai, from May 1 to Aug 31, 2020, after which cases declined or plateaued at lower levels;7 and third, the 4-month period encompassing the second wave of the pandemic in Chennai, from March 1 to June 30, 2021, associated with emergence of the delta SARS-CoV-2 variant (B.1.617.2)

Summary

Introduction

India is among the most severely affected countries in the ongoing COVID-19 pandemic, with over 458 000 deaths reported by Nov 1, 2021. Analyses informed by population-based serosurveys suggest that reported COVID-19 deaths might underestimate true mortality by a factor of seven to ten, in agreement with findings from other data sources such as household-based demographic surveys.. In high-income countries, all-cause mortality data from comprehensive vital registration systems have provided insight into the extent of underreporting of deaths attributable to COVID-19, as well as disparities in pandemic-associated mortality across socioeconomic and demographic groups.. As the extent of COVID-19 mortality and the effect of lockdown measures on other causes of death might differ in such settings compared with high-income countries, studies of this nature in India remain an important priority Analyses informed by population-based serosurveys suggest that reported COVID-19 deaths might underestimate true mortality by a factor of seven to ten, in agreement with findings from other data sources such as household-based demographic surveys. In high-income countries, all-cause mortality data from comprehensive vital registration systems have provided insight into the extent of underreporting of deaths attributable to COVID-19, as well as disparities in pandemic-associated mortality across socioeconomic and demographic groups. However, few studies of allcause mortality have been undertaken in India and other low-income and middle-income countries. As the extent of COVID-19 mortality and the effect of lockdown measures on other causes of death might differ in such settings compared with high-income countries, studies of this nature in India remain an important priority

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