Science

Testing for a new HIV vaccine failed

An experimental vaccine in a clinical study of 5 thousand people has proved completely ineffective and for this reason the experts of the US National Institutes of Health have blocked the trial. But we must not break down and the search for an AIDS vaccine goes on

Hiv
(photo: Stocktrek via Getty Images)

The test of the efficacy of a new vaccine for HIV has officially failed. The National Institute of Allergy and Infectious Diseases, part of the US National Institutes of Health (Nih), reports it. The study, called Uhambo (in the acronym HVTN 702), conducted on more than 5,000 people in South Africa, showed that vaccination was not effective , although no problems emerged regarding its safety. This result led Nih to block the administration of the drug and therefore the clinical study. For now, we do not have a vaccine for HIV and several attempts have been unsuccessful even if the research continues and several promising studies are underway to develop it.

The authors of the study, which started in 2016, involved about 5. 400 volunteers in South Africa , HIV negative and sexually active, aged between 18 ei 35 years. The participants, divided into two groups, received the experimental vaccine or the other a placebo, all in 6 doses for a duration of 18 months. After this period, sufficient to stimulate the immune response, the researchers analyzed the possible protective effects. To do so, they compared the number of new infections , starting from the beginning of the study (moment in which none of the participants had HIV) in the group treated with the experimental vaccine and in the control group.

From the results it emerges that among the vaccinated there have been 129 cases while among those who received the placebo 123 , absolutely comparable figures, which do not denote no increase or decrease of risk to contract the infection. For this reason, the experts concluded that the efficacy of the vaccine is zero and they stopped the administration of the drug recommending to continue the follow-up of the participants, who will still be monitored for the effects.

But this failure – if you can talk of failure in an environment where any result can make you learn – it will not stop the search for a vaccine . “We will continue to explore promising ways to prevent HIV with other vaccines and other strategies” , commented Glenda Gray , involved in the clinical study, “both in South Africa and in the rest of the world” . HIV-positive people in the world are almost 38 millions and about 7.7 in South Africa . The vaccine is essential to end this pandemic, experts agree, who will continue their efforts to get there.

He is also confident Mitchell Warren , always between the experts who blocked the trial, which is in charge of Avac, Aids Vaccine Advocacy Coalitio n, an international non-profit organization that works to find AIDS vaccines. “There are other drugs” , explained the expert in an article in Science, “in studies that evaluate the effectiveness and there is a slightly larger phase 1 pipeline [scelta di medicinali ndr] than we have never had so far ”.

In addition to other experimental vaccines, there are studies, including the trial Amp , who study and exploit the action of the largely neutralizing antibodies , antibodies that effectively neutralize viral strains of hiv multiples and which could lead to the development of a vaccine. These antibodies bind to specific regions on the surface proteins of HIV, neutralizing it. The difficulty (here some critical issues encountered in research on vaccines against Aids ), in fact, is that the virus does not expose on its surface the parts of itself that induce the antibodies necessary to annihilate the infection. For this reason, hitting them is difficult to work in this sector could bring important advantages on the road to preventing HIV.

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