The swine flu pandemic of 2009 killed an estimated 284,500 people, about 15 times the number that was confirmed by laboratory tests at the time, a new study has revealed. The study, by a group of scientists, said the toll might have been even higher - about  579,000 people. The original count, compiled by the World Health Organization, had put the number of deaths at 18,500.

Those were only the deaths confirmed by lab test, which the WHO warned was a gross underestimate because the deaths of people without access to health system go uncounted, and as the virus is not always detectable after a victim dies.

The study, led by Dr Fatimah Dawood of the US Centers for Disease Control and Prevention, also shows the pandemic’s impact varied widely by region, with 51% of swine flu deaths occurring in Africa and southeast Asia, which account for only 38% of the world’s population.

“This pandemic really did take an enormous toll,” Stuff.co.nz quoted Dawood as saying. “Results also suggest how best to deploy resources. If a vaccine were to become available, we need to ensure it reached the areas where the death toll is likely to be highest.”