The H1N1 vaccine will arrive too late to help most Americans who will be infected during this flu season, according to a study conducted by scholars at Purdue University.

The study also estimates that the virus - commonly referred to as the swine flu bug - will infect about 60 percent of the U.S. population, although only about 25 percent of Americans will fall ill.

"The model predicts that there will be a significant wave in autumn, with 63% of the population being infected, and that this wave will peak so early that the planned [U.S. Centers for Disease Control and Prevention] vaccination campaign will likely not have a large effect on the total number of people ultimately infected by the pandemic H1N1 influenza virus," the authors wrote in their study.

"The model predicts that the peak wave of infection will occur near the end of October in week 42, with 8% of the population being infected during that week. By the end of 2009, the model predicts that a total of 63% of the population will have been infected," the authors wrote in a conclusion that ignored the effects of a CDC vaccination program.

But even "when the model was modified to include the effect of the planned vaccination scheme," that adjustment yielded only "a relative reduction of about 6% in the total number of people infected" by the end of the year 2009.

"Based on our study alone it would be bad to discourage people from getting the vaccine, because what if our study is wrong,"