JurisdictionUnited States

It may be helpful, as one studies the claim of an unexpected injury from a product, to ask how the product was tested before it reached the market. Preclinical evaluation of the experimental vaccine looks at its injection-site reactions and examines a toxicological profile in animal models like mice or rabbits to determine how the vaccine works in a living system.2 The animal models provide some safety insights for the experimentation team. Then brave human patients can participate in the next phase, the human clinical trial stages, at which human safety and human health benefits are established.

At Phase I, the vaccine science team seeks to determine the safety profile, pharmacokinetics, and pharmacologic information. Initial administration of the test vaccine to human volunteers occurs as they are monitored in a medical setting, typically with one dose administered to a healthy individual. The team will assess vital signs, physical and neurologic status, lab testing (hepatic, renal, hematopoietic function), cardiac function, and any adverse events. That set of data is then shared with federal regulatory agencies.

At Phase II there is a continued evaluation of safety as well as initial development of evidence of efficacy. The goal is to determine whether further study should continue into Phase III. The trials are looking for "reactogenicity symptoms," both solicited and unsolicited reactogenicity symptoms.3

At Phase III, the challenge is to assess safety and efficacy of the vaccine in a large subject pool. This increased population of patients allows a comparison between the immune response of individuals receiving the vaccine and individuals in the "control group" who received a placebo.

After approval by the U.S. Centers for Disease Control and Prevention (CDC) and Food and Drug Administration (FDA), the vaccine may be made available to a more general audience of physicians and hospitals. Phase IV will study the long-term effects of the approved vaccine. Reporting of adverse reactions is required...

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