Patients with advanced aids often die from infections that do little harm to healthy people. why?

[120 total points] (public health) in one of the largest human experiments ever conducted, in 1954 a randomized controlled trial was run to see whether a vaccine developed by a doctor named jonas salk was effective in preventing paralytic polio. a total of 401,974 children (ages 6–9), chosen to be representative of those who might be susceptible to the disease, were randomized to two groups: 200,745 children (the control group c) were injected with a harmless saline solution (a placebo) and the other 201,229 children (the treatment group t) were injected with salk’s vaccine.what was the point of giving saline solution to the children who didn’t get the vaccine? explain briefly.

Which of the following choices is the most important to do before starting an exercise program? a. see your doctor b. talk to your friends for advice c. lift some weights d. measure your body fat

Which of these technological advances has improved flu vaccines? a. ct scans b. cell-based culturing c. egg production d. glucose monitors