Another setback in the fight against the HI virus: A vaccine candidate against the sexually transmitted immunodeficiency disease AIDS that is considered to be particularly promising does not provide adequate protection against HIV infection. This was announced by the American pharmaceutical company Johnson & Johnson after reviewing data from the pivotal clinical study.
“We are disappointed with this result,” said lead researcher Penny Heaton, according to a company statement. The phase III study (“Mosaico”) with 3900 subjects is being completed. According to the German HIV expert Hendrik Streeck, who was involved in the study along the sidelines, no other preparation had had such good prospects.
The poor results of the study now published would have “significantly slowed down the search for a vaccine,” explains Streeck, head of the Institute of Virology at the University of Bonn. “Until recently, I still hoped that this vaccine could work.”
Vaccine showed a good immune response in monkeys
According to the German expert, monkeys have shown a very good immune response against the virus. However, a study (“Imbokodo”) on a similar HIV vaccine had already been discontinued in the fall of 2021 (krone.at reported), which also dampened expectations in the “Mosaico” study.
The vaccine, the study of which is now being completed, is a so-called vector-based vaccine. A weakened cold virus is modified so that it can insert a blueprint for the virus into cells so that the immune system produces antibodies against HIV. In addition, the immune system is stimulated by the surface protein of the HI virus. A total of four vaccine doses would be needed.
1.5 million new AIDS infections per year
The battle against the immune deficiency disease AIDS is one of the greatest medical challenges worldwide. Most recently, about 1.5 million people contracted HIV each year. If an infection is left untreated, the virus weakens the immune system to the point where life-threatening illnesses develop. One then speaks of AIDS (Acquired Immune Deficiency Syndrome).
There are now medicines that protect against infection (PrEP) for people with an increased risk of infection. Daily intake is recommended. There are also drugs that inhibit the replication of the virus in infected people, so that AIDS does not break out.
Pathogens come in many varieties
The HI virus presents researchers with special challenges. The pathogen occurs in many different variants and changes relatively quickly, Streeck explains. This makes it difficult to develop a vaccine that protects across the board. In addition, the virus has a special surface on which immune substances stimulated by the vaccine can attack with relative difficulty.
Another challenge is that a vaccine should lead to the generation of fully protective, ie sterile, immunity. A short-term or minor infection despite vaccination is not possible because the virus directly attacks the immune system.
Already testing with multiple vaccines
In recent decades, several potential HIV vaccines have been tested in human clinical trials. With one of the vaccines, an efficacy study was able to show a 31 percent protection rate against infection, but this was far too low to warrant widespread use.
Source: Krone
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