Clinical Trial
Between 2004 and 2007, the National Institutes of Health conducted a STEP vaccine clinical trial—Phase IIB “test-of-concept” study.
The STEP study is the name of a clinical trial to test an experimental human immunodeficiency virus (HIV) vaccine. The STEP study enrolled 3,000 participants at sites in Australia, Brazil, Canada, the Dominican Republic, Haiti, Jamaica, Peru, Puerto Rico, and the United States. The study was designed to test an HIV vaccine, which aimed to stimulate production of immune system T-cells that can kill HIV-infected cells.
Based on its first evaluation of vaccine efficacy, the findings showed there were 24 cases of HIV infection among the 741 volunteers who received at least one dose of the investigational vaccine compared with 21 cases of HIV infection among the 762 volunteers who were vaccinated with the placebo. In volunteers who received at least two vaccinations, there were 19 cases of HIV infection among the 672 volunteers who received the investigational vaccine and 11 instances of HIV infection among the 691 volunteers who received placebo. The study investigators of the vaccine trials have decided to cease immunizations and are contacting study volunteers to inform them of the developments.

Reference:
National Institutes of Health (2007). National Institute of Allergy and Infectious
Diseases: Immunizations are discontinued in two HIV vaccine trials.
Retrieved from http://www.niaid.nih.gov/news/newsreleases/2007/
Pages/step_statement.aspx
The Internet, research further on STEP study and STEP vaccine clinical trials and its parameters.
Based on your research, understanding, and above information, answer the following questions:
•Prior to beginning this study, how would you have described the risks and benefits of the study to participants?
•What are the ethical issues surrounding this study at the beginning and when the decision was made to terminate the study?