HIV INFECTIONS IN VACCINE STUDIES

At least five volunteers in the US government's principal AIDS vaccine study have become infected with HIV, despite receiving the vaccine, through heterosexual intercourse, reports the Marketletter's US correspondent. Researchers are now trying to determine not only how well the vaccine works but also whether vaccination may have increased the likelihood of infection, and in one case even accelerated the progression of the disease.

Four of the five infections have been observed amongst patients who received either the Biocine or Genentech vaccines, which comprise a fragment of outer envelope of the virus. HIV infection has been confirmed in two low-risk volunteers as well as three considered at high risk of contracting the infection. One of the high-risk patients has undergone an unusually rapid decline in circulating CD4 lymphocyte numbers.

While the five case reports have not yet been published in the scientific literature, they have been discussed at scientific progress meetings, including a closed-door session at which it was debated whether or not the US National Institutes of Health should go ahead with plans to test the vaccine in thousands of new, uninfected patients.