London ? A flu virus as deadly as the one that caused the 1918 Spanish flu could kill as many as 81 million worldwide if it struck today, a new study estimates.

By applying historical death rates to modern population data, the researchers calculated a death toll of 51 million to 81 million, with a median estimate of 62 million.

That’s surprisingly high, said lead researcher Chris Murray of Harvard University. He did the analysis, in part, because he thought prior claims of 50 million deaths were wildly inflated.

The new work will be published in Saturday’s issue of the journal The Lancet.

The 1918 flu outbreak killed at least 40 million people worldwide.