The comparison between the AIDS vaccine race and the Covid-19 race is misleading

Less than a year. The delay in the development of the first candidate vaccines against Covid-19 has upset all precedents in medicine. And it leads to comparisons with other pathologies. On this world day in the fight against AIDS, one of them is making a strong presence on social media: why does this virus still not have its vaccine in 40 years of research when Covid already has one? nearly ten in a few months of a pandemic? For Étienne Decroly, virologist of the CNRS, this same question is misleading. Explain why.

Because if these two diseases are “virus”, they have many differences. Starting with the fact that they are not the result of infection with viruses belonging to the same family. Therefore, HIV is a “retrovirus“, explains the specialist in emerging viruses and new pathogens, namely that the replication of its genome requires the transcription of its RNA into DNA capable of integrating into the genome of the host cell.main feature“is that it attacks the immune system. Although coronaviruses are RNA viruses, they have a completely different replication strategy and do not attack the immune system.

The second is the type of infection that the two diseases cause. One is persistent, the other is acute. Essentially, this means that for HIV, once the genetic material is integrated into the cells, the cells persist in the body. On the contrary, for Covid-19, the genetic material of the virus is never transcribed and integrated inversely. This makes it easier for the body to control the infection. In short “the immune system can eliminate all the virus. If it does, the virus no longer circulates in the body“, summarizes Étienne Decroly.

The mechanics of these two viruses are all the more different because in the case of AIDS it is a dormant virus. A “Trojan Horse”, as the researchers call it. If we know the retrovirus family well, it really has the unique ability to be in latency. “Some infected cells do not express the virus and therefore escape detection by the immune system.”

Radically different functioning and propagation necessarily provoke distinct responses. In the case of AIDS, research is the key“a vaccine that must be sterilizing”. Any infection and integration of the disease must be avoided. Necessary against HIV, this feature is not the main problem of Covid-19, for which it is essential to acquire sufficient immunity to avoid developing severe forms. In short, to take Etienne Decroly’s conclusion: “When retroviruses, latency and the affected immune system are combined, vaccine development necessarily becomes much, much more complex.”

However, if the Facebook post suggests that there would be less effort in AIDS research, this is absolutely not the case. Étienne Decroly thus remembers the early 80s, when the virus had emerged and “dozens of industries have started experimenting with vaccines”. Without them succeeding. Of the “considerable effort” equivalent to those put in place to address this pandemic. But at another time. Questioned by RTBF, Jean-Christophe Goffard, director of the internal medicine department at Erasme hospital, confirms this idea. It is not a question of money. “There are a lot of financial resources that have been injected into this research, but also at a time when molecular biology was much less advanced than today.”

No preferential treatment therefore. However, it must be recognized that the industry, after having devoted significant efforts, “breathless” on the HIV issue. “Our economic model is based on the fact that the pharmaceutical industry develops vaccines and new molecules thanks to the profits it makes on the drugs or vaccines it sells”, remembers the CNRS researcher. However, the labs here are certain to sell their stocks massively. As proof, some countries have already ordered doses. It remains to be stressed, as Étienne Decroly does, that one should not claim victory too soon. Why despite the efficacy rates advanced by the laboratories have announced the development of a vaccine, many questions remain.

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