Question

Three hundred children attending an elementary school in Ethiopia without any prior history of malaria were each assigned at random to one of two groups after the investigators sought appropriate parental consent. The children in the first group received a new vaccine for malaria, and the children in the other group received a saline solution. After one year, the incidence of malaria was computed among the children based on whether they had received the vaccine or not. The children receiving the vaccine had a substantially lower incidence of malaria as a group than the children receiving the saline solution, thereby confirming the anticipated efficacy of the vaccine. What type of study is this?

• A. Randomized Controlled Trial
• B. Prospective Cohort Study
• C. Retrospective Cohort Study
• D. Case-Control Study

The following statement describes which phase of an RCT?

"Studies that gather preliminary data on effectiveness (whether the drug works in people who have a certain disease or condition). For example, participants receiving the drug may be compared with similar participants receiving a different treatment, usually an inactive substance (called a placebo) or a different drug. Safety continues to be evaluated, and short-term adverse events are studied."

• A.

  Phase 1

• B.

  Phase 2

• C.

  Phase 3

• D.

  Phase 4

Answer 1

ANSWER 1

RANDOMISED CONTROLLED TRIAL

We see in the question that a group of subjects are chosen based on certain characteristics and assigned randomly into study and control groups. Following which the study group is exposed to a vaccine while the controls are exposed to placebo. The effects are studied after a period of time.

This random assigning of individuals into study and control groups indicates that it is an RCT.

ANSWER 2

PHASE 2

There are five phases of Clinical trials.

• Phase 0 - Exploratory study involving very limited human exposure to the drug, with no therapeutic or diagnostic goals.
• Phase 1 - Studies that are usually conducted with healthy volunteers and that emphasize safety. The goal is to find out what the drug's most frequent and serious adverse events are and, often, how the drug is metabolized and excreted.
• Phase 2 - Studies that gather preliminary data on effectiveness (whether the drug works in people who have a certain disease or condition). For example, participants receiving the drug may be compared with similar participants receiving a different treatment, usually an inactive substance (called a placebo) or a different drug.
  Safety continues to be evaluated, and short-term adverse events are studied.
• Phase 3 - Studies that gather more information about safety and effectiveness by studying different populations and different dosages and by using the drug in combination with other drugs.
• Phase 4 - Studies occurring after FDA has approved a drug for marketing. These including postmarket requirement and commitment studies that are required of or agreed to by the sponsor. These studies gather additional information about a drug's safety, efficacy, or optimal use.

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