Risk experts are warning insurance companies that they may be underestimating their risk if they assume that a new influenza pandemic would be no worse than the 1918 influenza pandemic.

While some published studies have already illustrated the effects of various pandemic scenarios, most commonly a repeat of the 1918 influenza pandemic that had a mortality level of 0.67 percent in the US and even more severe effects in other countries, RMS says its analysis of the virology and epidemiological science shows that more severe pandemics are possible. There is a one in five chance of a pandemic that is more severe than that experienced in 1918.

H5N1, the virus that recently caused avian flu in Asia, has viral characteristics that will increase the likelihood of a virulent pandemic if it provides genetic material for human-to-human influenza transmission, according to RMS.