“Deep Disappointment” from Experts as Merck AIDS Vaccine Fails

A large international test of promising AIDS vaccine from Merck has failed, as 24 of 741 volunteers who received the vaccine in one part of the experiment later became infected with HIV. One important detail to note: it was not the vaccine itself which caused the infections. Testing has been halted.

AidsribbonThe AP reports: “The volunteers in the experiment were all free of HIV at the start. But they were at high risk for getting the virus: Most were homosexual men or female sex workers. They were all repeatedly counseled about how to reduce their risk of HIV infections, including use of condoms, according to Merck. In a statement, the NIH said a data safety monitoring board, reviewing interim results, found the vaccine did not prevent HIV infection. Nor did it limit severity of the disease “in those who become infected with HIV as a result of their own behaviors that exposed them to the virus” — another goal of the study.”

The vaccine experiment enlisted participants from Australia, Brazil, Canada, the Dominican Republic, Haiti, Jamaica, Peru, Puerto Rico and the United States


  1. Steve says

    “a large international test … has failed, infecting 24 of 741 volunteers who received the vaccine in one part of the experiment.” VERY MISLEADING PHRASING: you have ‘infecting’ refer to ‘test’, and that is NOT true. No scientific test would ever expose people treated with an experimental HIV vaccine to live virus. The researchers took people who were at high risk for HIV infection, and gave one group the real vaccine, and another group a placebo vaccine, and showed that subsequent HIV infection was no different in one group from the other. What’s more, both groups got in-depth HIV prevention counseling as part of the study. Please change the phrasing: ideas like this make it so hard for scientists to get people to participate in any HIV / AIDS study, when people think that scientists are infecting subjects.

  2. Mike B. says

    @ Steve:

    I was very alarmed and confused by that phrasing as well, and it took reading the full article (which, yeah, I should do anyway) to clear up that frightening figure.

  3. BeeDee says

    Yes, definitely not a test, a blind study. The other problem with this study is the high number of admitted “sex workers”. The study lacked specificity of effectiveness for “casual” exposure. Perhaps the vaccine was effective enough to manage – let’s call it limited exposure.

    I’m beginning to think that AIDS vaccine research in the hands of the drug companies and biotechnology firms is never going to work – they abandon work immediately if it appears they won’t get the big score. I wish 3M, Dupont, or GE would get in on this. Their corporate cultures are based on direct research AND investing in the opportunity of “happy accidents”. It’s that kind of approach that scores the incremental wins that finally win the war.

    We haven’t heard from the French lately, have they given up?

  4. David says

    First, it’s irrelevant whether or not exposure was casual or limited or what say you… for an HIV vaccine to receive approval it’s going to need to be 100% effective. Otherwise, can you imagine the result?

    Second, I wouldn’t throw away all trust in the drug companies and biotechs as a result of a failed study. These type of failed studies happen constantly in all types of therapeutic areas. Since HIV is specific to humans, a drug to combat HIV would need to be tested primarily in humans for efficacy, so tests like this are much bigger news than a similar failure which may have been seen in rats or dogs for an antiplatelet med, for instance.

    Truth be told, though we are still a ways off, there are a NUMBER of promising compounds and techniques in development. The great majority of these are in early development, but don’t lose hope.

  5. 24play says

    David, an HIV vaccine will not need to be anywhere near 100% effective to be approved. Even a vaccine that is 50% or 65% effective would drastically improve the situation in countries where HIV is rampant (or elsewhere, among populations considered at high risk).

    Many vaccine researchers have come to believe development of a silver-bullet vaccine is, if possible, decades away. In the past few years, a lot of the discussion of a possible HIV vaccine has shifted to the possibility of combining a few vaccines that show 20% to 30% effectiveness—and work by different mechanisms—into one shot that might prove to be 50% to 85% effective.

  6. 24play says

    Anon: No, no, no.

    All HIV vaccine trials have extensive pre-enrollment counseling that makes it absolutely clear that the vaccine is experimental, that it may not confer any immunity, and that half the people in the trial will be receiving a placebo that confers absolutely no immunity. Enrollees are also counseled on HIV prevention, including proper use of condoms.

  7. Gregg says

    They may have received all the couseling in the world, but when they were in that moment deciding if they should bareback it – you can’t tell me that there wasn’t a little bird tipping the scales saying, “maybe you ARE immune”.

    I’m not blaming the vaccination test. Trials are necessary. But human psychology cannot be discounted as to at least giving a small boost the the number of infected participants.

  8. 24play says

    Actually, Gregg, the people who volunteer for clinical trials and other health studies tend to be, on average, more responsible than the average Joe. Trial participants are more concerned about their health than nonparticipants, and they behave accordingly.

    There was a really excellent article on this in last week’s NYT magazine:


    In it the writer points out that in clinical trials and other studies of nutrients/drugs/lifestyle modifications, it’s not uncommon for both participants receiving the treatment/intervention being tested AND those in the control group (receiving a placebo or otherwise not partaking of whatever intervention is being tested) to have health outcomes significantly better than the general population. It’s called healthy-user bias. The people who volunteer for these things tend to be healthier (i.e., make better choices).

    That doesn’t rule out adverse effects of human psychology, as you’ve described, in individual cases. But it makes it unlikely to be a factor in the results of large trials or studies.

  9. Brandon says

    We already have a 99% effective vaccine…it’s called protected sex.

    That sounds cute and all, but a piece of plastic affects the human immune (hence “vaccine”) not one bit. This is a virus we’re talking about and further, it’s not only transmitted sexually.

  10. Craig says

    Was there no control group? 24 of some 700 volunteers doesn’t mean much to me, unless they give the figures for a control (placebo) group. If the infection rate is significantly lower for the non-control group, then I say pursue it!

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