Experts are “optimistic” an HIV vaccine could be available as soon as 2021.
Three jabs are entering the final stage of testing before they get put forward for approval.
While all the injections could still fail, the team are more hopeful than ever before.
Dr Susan Buchbinder, director of the Bridge HIV research program at the San Francisco Department of Public Health, called it “perhaps one of the most optimistic moments we have been in”.
“We have three vaccines being tested in efficacy trials and it takes quite a bit to actually be promising enough in the earlier stages stages of trials to move you forward into an efficacy study,” she told nbc news.
All three regimens are expected to require multiple jab doses in order to protect at-risk people from infection.
This comes more than three decades are hopes of an HIV vaccine were first raised in 1984. The then Secretary of Health and Human Services Margaret Heckler claimed a jab could be available in just two years.
One of the three jabs under development, HVTN 702, is based on the “old” candidate RV144, which was not effective enough to reach the drug market.
Nonetheless, RV144 still lowered the rate of HIV infections by around 30%. Although a “modest” reduction, the “landmark” jab was the first to ever prevent virus transmission, according to the National Institute of Allergy and Infectious Diseases (NAID).
HVTN 702 has been “modified in an attempt to increase the magnitude and duration of vaccine-elicited protective immune responses”. Results of a trial are expected late next year.
Dr Anthony Fauci, director of NIAID, claims even a “partially-effective” jab could be a “game changer for turning the epidemic around”.
Also under development is Imbokodo, with trials specifically testing the vaccine in thousands of women in sub-Saharan Africa.
Of the 1.8 million new HIV infections worldwide in 2016, 43% were in east and southern Africa, of which women and girls were “disproportionately affected”, the National Institutes of Health reported.
Imbokodo is based on a “mosaic” of targets that bring about an immune response against a range of HIV strains. Results of a trial are due in 2021.
Following a similar mosaic approach is the third vaccine Mosaico. The two jabs are “largely identical” but have “slightly different formulations”, nbc reported.
Unlike Imbokodo, Mosaico will reportedly be tested in heterosexual and transgender men to determine its effectiveness in different high-risk groups. Results are expected in 2023.
Data for the vaccines is positive so far, with Dr Fauci claiming there is no obvious reason for the studies to be terminated.
If this does occur, however, existing treatments may be enough to stem the HIV epidemic.
What are the existing treatments for HIV?
Around 37.9 million people around the world were living with HIV last year, of which 1.7 million were “new” infections, according to HIV.gov.
In the UK alone, 103,800 people are thought to have HIV, National AIDS Trust (NAT) statistics show. Of these, one in 14 are unaware they carry the infection.
HIV is treatable if caught early, with 97% of those on therapy in the UK being “virally suppressed”. This means they cannot pass the virus on even if they have unprotected sex.
Left untreated, however, HIV can develop into acquired immune deficiency syndrome (AIDS).
This occurs when the immune system is so severely damaged by HIV, the patient is at risk of life-threatening infections and diseases.
PrEP (pre-exposure prophylaxis) is also available for those without the infection if they are at higher risk.
Taken before and after sex, it “blocks” HIV from taking hold, according to the Terence Higgins Trust.
PrEP is available in England as part of a trial but more readily accessible in Scotland and Wales. Northern Ireland “will be offering initial consultation and assessment appointments for a pilot trial”.
It has to be taken within 72 hours of “coming into contact with the virus” and continued every day for one month, according to the NHS.
Approved in the US, PrEP is recommended for those in a relationship with an HIV+ partner, as well as “gay or bisexual men who have anal sex without a condom”.
Anal sex may be particularly problematic due to the lining of the anus being more delicate than that of the vagina, according to Avert. This means it is more easily damaged, allowing the virus into the body.
The Centers for Disease Control and Prevention also recommends PrEP for straight people who do not always use condoms while having sex with someone of “unknown HIV status”.
Studies have shown the drug regimen reduces the risk of HIV via sex by around 99% when taken “consistently”. It also lowers transmission via injectable drugs by nearly three quarters (74%).
PrEP has faced controversy over the years, with some questioning whether it may encourage risky sexual behaviour.
It is also expensive, setting a user back up to $14,000 a year (£10,835) in the US, The Guardian reported.