FEARS that HIV vaccines may encourage infection with the virus have largely been laid to rest. This could revive the search for a vaccine.
In September 2007, pharmaceutical company Merck halted its STEP trial of an HIV vaccine because it appeared to work no better than a placebo. Then it emerged that recipients of the vaccine who had previously caught the cold virus were more likely than those who hadn’t to be infected with HIV, sparking fears that the vaccine made HIV infection more likely.
The vaccine consisted of a deactivated cold virus loaded with three HIV genes that…
