About the Mumbai COVID-19 Data
The Brihanmumbai Municipal Corporation (BMC) started releasing a detailed daily PDF filled with information on a variety of indicators such as mortality, containment zones, bed capacity, vaccinations, etc. from June 2020. As can be imagined, such data is extremely useful not only for formulating short-term policy measures but also for assisting longer term academic research. A long-standing issue with using the data, however, has been that the authorities follow a process of replacing the PDF each day with fresh information and removing the prior day's document. This practise has limited any kind of temporal analysis till now.
At IDFC Institute, we've been able to gather all such PDFs from July 2020 until the present. We are in the process of converting all relevant indicators to a machine-readable output and will put them out as a public-facing database in due course. In the meantime, we will put out a brief analysis of them along with the related datasets. We've started by compiling and analysing all mortality data over time, as outlined below.
Mortality Data analysis
As of May 05, 2021 the city of Mumbai — this includes BMC-governed area i.e., Mumbai city, and the Eastern and Western suburbs — has recorded 13,603 COVID-19 related deaths, of which 95% occurred in patients over the age of 40. The 60-70 age group has been the most affected (28% of total deaths). This is in line with reported mortality in India showing a significantly higher risk of death for older individuals: the government announced in March 2021 that 88% of all deaths in India were in people over the age of 45. A detailed look at the mortality data leads to several observations.
First, the true toll of COVID-19 remains unknown. Limited access to testing, conservative definition of COVID-19 deaths and inconsistent cause of death registrations have led to an underestimation of COVID deaths. As a proxy, analysing excess deaths can help get a better sense of the COVID-19 toll. For the calendar year 2020, the BMC reported 111,942 deaths, representing a 24% increase from the previous five years and an excess mortality of over 20,000 deaths (average of 90,092 deaths per year). For the same period, the BMC registered 11,116 COVID-19 related deaths. One of the major caveats of this approach, though, is that we know that the pandemic has two opposing effects on mortality. On the one hand, it caused a reduction in deaths due to a decrease in road accidents or airborne and infectious diseases owing to increased hand washing and mask wearing. On the other hand, mortality increased for many pathologies due to delayed access to diagnosis and care.
Second, the peak of mortality was observed during the first wave. Although the number of cases increased to unprecedented heights in April 2021, the deadliest months of the pandemic seem to have been the first months with 1,694 recorded deaths in July 2020 (potentially more in June but no consistent data to support it). In April, despite the high number of total cases recorded, the case fatality ratio was lower. This can be explained by better clinical management of severe cases, impact of vaccination or lower virulence of circulating strains.
Third, the age distribution of deaths seems to have changed in the second wave. The proportion of 60+ deaths in overall deaths in April 2021 was 67% of all deaths down from 75%-82% in the previous six months. This could be explained by the vaccination campaign with 1 million people over the age of 60 vaccinated in Bombay as of May 5, 2021.
Understanding COVID-19 mortality is essential to develop the most appropriate and effective response policies. More data is essential to better understand these trends, especially on the prevalence and virulence of the strains circulating and on vaccine effectiveness.
Disclaimer : All visualizations are based on the age-wise totals available in the report as of 5 May, 2021.