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Vaccine trial

(Redirected from Vaccine trials)

A vaccine trial is a scientific experiment that uses one or more groups of test subjects to statistically judge the efficacy of a vaccine.

Methodology

A basic trial might involve forming two groups from a random sample of the target population. One group receives the vaccine while the control group receives a placebo. Data on antibody production and immunity to the disease in question is collected from both groups some time after the administration of the vaccine or placebo, and a statistical test is performed on these two sets of data to determine whether or not there is any statistically significant difference between them. If the vaccine produces no stastically sigificant results, then it is rejected. Side effects of the vaccine are also noted, and these too contribute to the decision on whether to license it.

Methodological issues and problems

Vaccine trials may take months or years to complete, since a sufficient time period must elapse for the subjects to react to the vaccine and develop the required antibodies. Antibody production is regarded as sufficient to prove the vaccine's effectiveness, and it is rare for subjects to be exposed directly to the biological agent (usually a virus or bacteria) the vaccine is supposed to provide immunity against. Assessing the severity and likelihood of side affects in the target population is extremely difficult because of the diversity of patients and the vast number of possible interactions with other medicines and environmental factors.

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