Two of the world’s leading HIV experts have suggested we are moving closer to an useable HIV vaccine. There are currently three vaccines undergoing human trials. These vaccines are known as HVTN 702, Imbokodo and Mosaico.
Dr. Susan Buchbinder is director of the Bridge HIV research program at the San Francisco Department of Public Health. She is also chair of both the Imbokodo and Mosaico trials.
She told NBC, “We have three vaccines currently being tested in efficacy trials and it takes quite a bit to actually be promising enough in the earlier stages of trials to move you forward into an efficacy study.”
She called this moment, “perhaps one of the most optimistic moments we have been in.”
Trials of Imbokodo began in South Africa, where more than 50% of women aged 18-25 are living with HIV, began in 2017.
Mosaico, which is a very similar form of vaccine to Imbokodo, began last month. Both use a ‘mosaic’ of immunogens to provoke an immune response to a variety of different strains of HIV. They require six injections over four separate sessions.
While both are being trialed in South Africa, Mosaico will also be trialed in 3,800 gay men and trans people at 57 sites in the US, Latin America, and Europe.
The other vaccine, HVTN 702, was developed following the failure of an earlier vaccine, RV144. That vaccine was only found to reduce HIV infection by 30%, which is not good enough to be put to widespread use. Since that vaccine’s failure in the late 00s, researchers at the National Institute of Allergy and Infectious Diseases (NIAID) have been modifying it to be more effective.
The new vaccine has been on trial in South Africa since 2016.
Dr. Anthony Fauci, director of NIAID, says that even a vaccine that proved to be 50% effective would dramatically reduce infection rates in places such as sub-Saharan Africa. The less number of people in a population that carry the virus, the less chance of it being passed on to others.
Fauci says if used in conjunction with PreP and Treatment as Prevention (getting newly diagnosed people on to medication quickly to make them undetectable), even a partially effective vaccine could prove worth deploying sooner rather than later.
“If one or more of these vaccines look good, have a 50-60 percent efficacy, I think that’s going to be the game-changer for turning the epidemic around.”
The results of the HVTN 702 could arrive late next year.
When vaccines or new medications are trialed, the trial can be stopped early, That happens if the product being tested shows overwhelming evidence that it works, or if it shows no evidence of working or even causes harm. As yet, none of the trials have yet been stopped. This suggests the vaccines are having an effect but none are an unqualified success.
However, Fauci believes that even a partially effective vaccine, when used in conjunction with other methods, may tip the tide against HIV.
In the US, President Donald Trump pledged earlier this year to reduce the incidence of HIV domestically by 75% in 5 years, and by 90% by 2030.
In addition to PrEP, treatment as prevention, and the vaccine trials, NIAID and the Bill and Melinda Gates Foundation announced in October plans to each invest at least $100 million over the next four years toward developing an affordable, gene-based cure for HIV.
Matthew Hodson, chief executive of HIV information service NAM, told Queerty: “This is an exciting time in vaccine development. It’s not expected that any of these vaccines will offer 100% protection but if they can offer 50% protection or more, that would be useful for communities with high rates of HIV.
“We’ve seen that a combination approach to prevention, including condoms, PrEP and getting people tested and virally suppressed (aka ‘undetectable’) on treatment, drives down new infections. Adding another powerful tool to our prevention kit could make a big difference.”