HIV Vaccines Show 80% Efficacy in Early Tests

Vaccines stimulate the production of copies of this HIV protein, but in different locations. The first approach uses a more traditional method where the cell is directed by the vaccine to produce the so-called ‘envelope’ proteins free and circulating—ready to bind to the virus. The second approach, with mRNA, instructs the cell to produce the same proteins, but attached to the cell membrane, mirroring the structure of HIV. Human trials involved 108 healthy individuals aged 18 to 55 in ten locations in the US. Participants were divided into three groups—two received mRNA vaccines and one received the traditional model with free proteins. All vaccines were manufactured by the pharmaceutical company Moderna. Each participant received three doses (high or low) of only one of the vaccines, with weeks apart. Participants and researchers did not choose which vaccines each patient would take; the vaccine was randomly determined. Approximately 80% of participants who received any of the mRNA messenger vaccines produced antibodies capable of blocking HIV from entering the cell. However, only 4% of participants who took the vaccine with free ‘envelope’ protein produced an immune response. All three vaccines were well tolerated by most participants, in both high and low doses. Only seven participants (or 6.5% of those studied) had reactions, including large, itchy skin rashes. Five of them experienced symptoms for more than six weeks, some for years, as the tests started in 2022. Reactions were seen in patients who received all vaccines, in any doses. A mix of vaccines was also tested. Another clinical trial by the same group of researchers in May investigated a strategy to protect people from more HIV variants: giving an initial mRNA vaccine and complementary doses of the other two vaccines. In these tests conducted in the US, Rwanda, and South Africa, the results were promising.