Which of the following is true about pathogens like shigella, e.coli. salmonella, norovirus, and hepatitis a

[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.

According to naeyc, are the youngest age group that may be out of the hearing range of supervising teachers for short periods of time. preschoolers infants kindergarteners toddlers

Define and describe the different types of risk factors