<p>VaxGen's experimental AIDS vaccine couldn't block HIV infection among volunteers in Thailand, the Brisbane company said Wednesday, in another blow for the closely scrutinized drug.</p>
<p>The vaccine, dubbed AIDSVAX, had no noticeable effect on infection rates among the 2,546 intravenous drug users in Bangkok who volunteered for the study. Nor did it slow the disease's progress among volunteers who took the vaccine and later contracted HIV.</p>