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Why is it so hard to make a vaccine against HIV?When the then US Health Secretary Margaret Heckler made her 1984 forecast that a vaccine would soon be developed, the experts listening knew better than to expect a vaccine in a couple of years. Several scientists seated in the packed auditorium "blanched visibly" at Heckler’s declaration, according to Randy Shilts’ history of the early epidemic, And the Band Played On.1 They were right to be cautious. It had taken 105 years after the discovery of the typhoid bacterium to develop a vaccine for typhoid. For whooping cough (pertussis) it had taken 89 years; for polio and measles 47 and 42 years respectively. But the time lag was getting shorter. It had only taken 16 years from the discovery of the hepatitis B virus to the development of a vaccine.They were right to be cautious. It had taken 105 years after the discovery of the typhoid bacterium to develop a vaccine for typhoid. For whooping cough (pertussis) it had taken 89 years; for polio and measles 47 and 42 years respectively. But the time lag was getting shorter. It had only taken 16 years from the discovery of the hepatitis B virus to the development of a vaccine. Two years later at the Bangkok International AIDS Conference he was much less optimistic.2 Esparza pointed out that the search for a first generation of HIV vaccines
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Why is it so hard to make a vaccine against HIV?
By SREEREMYA.S
When the then US Health Secretary Margaret Heckler made her 1984 forecast that a vaccine would soon be developed, the experts listening knew better than to expect a vaccine in a couple of years. Several scientists seated in the packed auditorium "blanched visibly" at Heckler’s declaration, according to Randy Shilts’ history of the early epidemic, And the Band Played On.1
They were right to be cautious. It had taken 105 years after the discovery of the typhoid bacterium to develop a vaccine for typhoid. For whooping cough (pertussis) it had taken 89 years; for polio and measles 47 and 42 years respectively. But the time lag was getting shorter. It had only taken 16 years from the discovery of the hepatitis B virus to the development of a vaccine.
Almost thirty years after the discovery of HIV, however, a truly preventive HIV vaccine is clearly still many years ahead. Researchers previously optimistic about a vaccine have tempered their optimism in the last decade. Nonetheless the development of a vaccine for such a novel and difficult pathogen, with only a quarter-century of knowledge to work with, is not necessarily ‘behind schedule’. Researchers have had to temper undue optimism.
At the Barcelona International AIDS Conference in 2002, for instance, Jose Esparza, who was working at the time for the World Health Organization Vaccine Initiative, predicted that at least one Phase III trial of a workable vaccine would be underway within the following three years - and that there should be at least one effective HIV vaccine available by 2009.
Two years later at the Bangkok International AIDS Conference he was much less optimistic.2
Esparza pointed out that the search for a first generation of HIV vaccines – ones that used simple viral proteins to elicit an antibody response – was started soon after HIV was discovered in 1984 and appeared to have finally run into the ground 20 years later in February 2003 when the first-ever Phase III efficacy trial of an HIV vaccine ended with failure (though AIDSVAX later secured for itself an unexpected afterlife, as we will see below).
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