Given limited testing and vital statistics data, few measures of the COVID-19
IFR exist for developing countries. In Europe and North America, COVID-19 fatality rates are known to vary by age, gender, and comorbidities. But existing model-based estimates for the developing world have not fully accounted for these factors in predicting IFRs.

Using variation in demographics, comorbidities, and health system capacity,
the newly published study in the BMJ Global Health predicts COVID-19 IFRs for 187 countries, producing estimates that range from 0.43% in Western Sub-Saharan Africa to 1.45% in Eastern Europe. Despite lower measured health system capacities, predicted IFRs for most of Sub-Saharan Africa nonetheless remain well below IFRs for high income
countries, while Eastern Europe is predicted to fare particularly poorly.

Information about COVID-19 is evolving quickly though, and it’s worth noting how our understanding of the infection fatality rate has changed even during the time of peer review for this paper.

First, one factor which the paper did not directly consider, but which has proved to be an important risk factor, is obesity. This factor has been confirmed to be independently linked to increased COVID-19 severity and higher risk of death even after accounting for commonly correlated comorbitities, such as hypertension and diabetes, which the BMJ Global Health analysis did account for.

Second, as time passes, there are also signs that the chances of surviving COVID-19 are increasing. Specifically, since the manuscript submission, COVID-19 case fatality rates (i.e. the percentage of identified cases which result in deaths) seem to have diminished. Although some factors may suggest that the same is true for IFRs - due to improved treatments, earlier diagnosis and, possibly, decreased viral load due to the season - this is not necessarily the case: more widespread testing may simply be increasing the infected count with mild cases, which were previously undiagnosed, or particularly vulnerable populations may be less exposed to the virus. 

Third, the new BMJ Global Health study focuses on predicting infection fatality rates where data are missing. But more and more data are beginning to become available. Particularly intriguing have been reports from new seroprevalence studies in the developing world, including several countries in Africa and South Asia, that show high rates of antibodies, suggesting far more infections than in official case counts. By implication, if estimates of excess mortality are correct, these higher seroprevalence rates would imply much lower infection fatality rates than predicted just months or even weeks ago.

The infection fatality rates predicted in this new BMJ Global Health study are one important element in understanding the COVID-19 pandemic. Though individual risks may appear relatively small, policymakers must consider these probabilities compounded over potentially affected populations of many millions to understand the potential reach of the disease. For example, it was recently announced that COVID-19 is on track to be the 3rd leading cause of death in the U.S.A. for 2020, illustrating how even seemingly low infection fatality rates can add up to an enormous human toll.

Click here to read the paper in full.