From 2007? The study of "step" (HVTN502) found that after HIV vaccine promotes immune cells to attack HIV, it may increase the risk of immune cells being infected by HIV. The "HVTN 505" research started in 2009 also failed in 20 17, because the experimental vaccine could neither stop the spread of HIV nor reduce the viral load. One of the biggest challenges that hinder research and development is the global variation of HIV genome and the high diversity of virus strains.
So far, only the "RV 144" experiment jointly conducted by Thailand and the United States in 2009 has brought a glimmer of light. After the subjects were vaccinated with "RV 144" experimental vaccine (primary immunization preparation ALVAC and booster immunization preparation AIDSVAX B/E), the possibility of being infected with HIV in a short time was about 60% lower than that of the subjects vaccinated with placebo. However, this preventive effect was greatly reduced within one year-by the end of three and a half years, this advantage was reduced to 365,438+0%, so it is not recommended to promote this vaccine.
At present, AIDS prevention means are limited, mainly including condoms and antiretroviral therapy, which is called pre-exposure prevention (PrEP). Jorge Sánchez, an epidemiologist at the Center for Technology, Biomedicine and Environmental Research in Lima, Peru, said that PrEP needs to take medicine every day, and it is difficult for most people to adhere to it and it is not easy to get medicine. Therefore, a preventive plan of injecting vaccines several times every few years is a better choice.