Low and middle income countries are badly affected by the 2019 coronavirus disease (COVID-19) pandemic caused by the infectious agent Coronavirus 2 (SARS-CoV-2).
A new US study by researchers at Dartmouth College, Development Data Lab, IDFC Institute, Johns Hopkins University, and the University of Chicago shows that the infectious mortality rate (IFR) in men could double that of women and is increasing much less in old age than in high-income countries.
India’s COVID-19 outbreak
The coronavirus pandemic reached India in January 2020 when the country reported its first case. The first cases were residents who have returned from Wuhan, China, the place where the virus is believed to have emerged. However, in May 2020, the country reported an increase in COVID-19 cases. Many of them were tourists who can return after trips to Italy, the United Arab Emirates, Thailand and Iran, among other places.
From there, localized transmission has occurred and thousands of new cases have been reported. To date, the infection rate has reached a staggering 10.39 million confirmed cases and over 150,000 deaths.
Infection death rate
Measuring the infectious mortality rate for SARS-CoV-2 has been one of the priorities of scientists since the beginning of the pandemic. Reliable estimates by the IFR are important in policy decisions and vaccine allocation plans.
This will determine who is at greater risk of developing severe COVID-19 and dying from complications of the disease in a given country. Globally, scientists have classified older adults and those with underlying health conditions as those at the highest risk for death from COVID-19.
Estimating infectious mortality rates requires an accurate measurement of the number of infections and deaths in the population due to COVID-19. This can be measured by finding the number of positive tests.
Most of these studies, however, focused on high-income countries. There is limited data on IFRs in low and middle income countries like India. In those countries where testing is not widely used, the number of infections and deaths may not be adequately reported. This can affect the IFR calculation and estimates.
The new study, published on the MedRxiv * server before going to press, shows that IFR in India is about twice as high for men as it is for women, is heterogeneous across contexts, and increases much less with age than studies in countries with high Income .
To arrive at the study results, the researchers used three data sources from India, which are excellent for calculating age-specific IFRs. They used population-representative seroprevalence surveys in Mumbai and Karnataka. The researchers calculated the IFR by matching the results of the surveys.
In addition, the team used a survey on COVID-19 prevalence among short-term emigrants returning to Bihar state. These are mainly men of working age. The team endeavored to measure age-specific IFRs at all three locations and to compare them with international estimates.
The study results showed that IFRs were lower than measures in higher income countries, especially at the age when most deaths occur. For both men and women, there are differences in the IFRs between the three locations in the country.
The study also found a weaker increase in IFR with age than in other countries. It is known that the pattern of death or mortality in low- and middle-income countries is younger than the age distribution predicts. This could be related to a flatter age profile for mortality.
In addition, migrants to Bihar have a higher IFR because they were among the most socio-economically stressed people in the country.
The researchers noted that deaths in the country may not have been adequately reported, which could affect the IFRs calculated in the study. They suggest that better epidemiological surveillance and accounting for SARS-CoV-2 improves the ability to understand the risk of death from SARS-CoV-2 in lower-income situations.
* Important NOTE
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or be treated as established information.
- Cai, R., Novosad, P., Tandel, V., Asher, S. and Malani, A. (2021). Representative estimates of the death rate from COVID-19 infections in three locations in India. medRxiv. doi: https://doi.org/10.1101/2021.01.05.21249264, https://www.medrxiv.org/content/10.1101/2021.01.05.21249264v1