Had a strain of influenza akin to that which caused the 1918 influenza pandemic emerged in 2004, researchers estimate it could have killed 62 million people worldwide.
The vast majority of deaths (96 per cent) would have occurred in poor countries where "scarce health resources are already stretched by existing health priorities," report Dr Christopher JL Murray, of Harvard University, Cambridge, Massachusetts and colleagues in The Lancet medical journal.
The investigators used death registration data gathered during the 1918-1920 influenza pandemic in 27 countries to estimate global mortality if such a similar pandemic should happen today.
Extrapolation of 1918-1920 mortality rates to the worldwide population of 2004 indicates that between 51 and 81 million individuals would die if a similar pandemic were to occur today. "If this mortality were concentrated in a single year, it would increase global mortality by 114 per cent," the team reports.
"Irrespective of the lethality of the virus, the burden of the next influenza pandemic will be overwhelmingly focused in the developing world, as has been suggested for the 1918-1920 pandemic," they predict.
In an accompanying editorial, Dr Neil Ferguson of Imperial College London, UK, makes the point that this analysis "highlights the stark fact that health inequality is scarcely less now than in 1918 and that medical advances of the past 90 years are unlikely to benefit much of the developing world in any future pandemic."
So what can be done "to mitigate the depressingly familiar wealth-related distribution of disease burden predicted by Murray and colleagues?" Dr Ferguson asks. "Access to vaccines, anti-virals, and antibiotics for the most vulnerable populations is clearly part of the solution," he states.
Low-cost public health measures such as school closure, quarantine and masks could offer the most hope to countries without access to medical interventions. However, more study is needed to determine the true impact of these measures, Dr Ferguson notes.