Saint Louis County has received more than 500 cases since Wednesday . Thousands of Americans being prepared for trials in hundreds of sites across nation . Patients will be able to keep healthy while they are monitored for two months . Doctor says virus could kill one in five people this fall and peak in October .
Saint Louis University has received more than 500 responses since Wednesday . Thousands of Americans being recruited for trials in dozen of sites across nation . Patients will be asked to keep progress while they are monitored for two months . Doctor says virus could sicken one in five people this fall and peak in October .