Last month, Nature published a letter questioning the ethics and validity of a controversial HIV drug trial, in which one drug (nevirapine) was compared with another HIV drug and not a placebo.
Its author, Valendar Turner, maintained that using "a placebo is the only way a scientist can assess a drug's effectiveness with scientific certainty".
In this letter to Nature, Brooks Jackson and Thomas Fleming, researchers on the HIV trial, defend the decision to stop using the placebo. During the trial, they say, research showed that the second drug in the trial (zidovudine) could reduce transmission of HIV in pregnant women by 50 per cent compared to a placebo.
The scientists felt it was unethical to continue giving some women the placebo when they knew they could give them an effective drug. Following recommendations by the US Centers for Disease Prevention and Control and National Institutes of Health among others, they altered the trial to replace the placebo with zidovudine.
Jackson and Fleming argue that if a drug is proven to be more effective than another that has itself been shown to be better than a placebo, the trial is valid.
At the end of the trial, the researchers concluded that nevirapine was more effective in reducing the transmission of HIV than zidovudine.