The STEP trial with Merck's HIV vaccine was stopped recently because the number of deaths from AIDS was greater in those who received the active vaccine than in those who got an ineffective placebo.
The vaccine was built by attaching three HIV genes — not the virus — to an inactivated cold virus (adenovirus) that could not replicate and cause colds. Since the vaccine did not contain live or killed HIV virus, it could not itself cause AIDS. So, the reason for the greater number of deaths in the vaccine-treated participants is unclear.
These findings raise the possibility that the use of the adenovirus to deliver HIV genes was responsible for the greater number of AIDS infections and deaths. Whatever the reason for the failure of the vaccine, this unfortunate outcome raises concern that people will be unwilling to participate in future trials of HIV or other new vaccines.
A report in the November issue of the Journal of the American Medical Association (JAMA) shows the tremendous value of vaccines for the prevention of diseases, like AIDS, that cannot be cured. In fact, successful vaccines may be the greatest achievements of medicine and public health.
For vaccines developed prior to 1980, for example, there was nearly a 100 percent fall in the number of deaths from diphtheria, measles, poliomyelitis, rubella (German measles), smallpox, mumps, tetanus, and pertussis (whooping cough). The decline in the number of illnesses attributed to these disorders was also nearly 100 percent for all but mumps (96 percent), pertussis (92 percent), and tetanus (93 percent).
Vaccines approved or recommended after 1980 showed smaller improvements. In comparison to the pre-vaccine period, deaths in 2006 fell by 87 percent for hepatitis A, 82 percent for chicken pox, and 80 percent for hepatitis B.
It is too early to know the success rate of the newest vaccine — the vaccine against human papillomavirus for the prevention of cervical cancer — or how many young women will take advantage of it.
In addition to the reductions in deaths and suffering from these diseases, many billions of dollars have been saved in direct health care costs for doctor visits and hospitalizations and for the indirect costs from disability and time lost from school and work.
The remarkable success of these vaccines underscores the value of money spent to support the research needed to develop and test vaccines to prevent HIV and other infections like malaria (which still kills between 2 and 3 million people a year).
Equally important is the continued need for people to volunteer, despite the possible risks, for trials testing the vaccines after they are developed.
