HIV vaccine 'shows promising results in humans'

"HIV vaccine human trials leave scientists 'cautiously pleased'," The Independent reports, following the results of a new clinical trial that tested a HIV vaccine in both humans and monkeys.

Researchers recruited 393 people from a number of countries to take part in the trial.

These people were healthy and considered at low risk of HIV-1 infection (the most common strain of the HIV virus).

They received either the vaccine or a placebo (dummy treatment), and were then monitored for a year.

At the same time, a similar study was carried out in 72 rhesus monkeys so the results could be compared.

The aim of the study was to see whether the vaccine was safe, and whether people who received it still showed signs of the vaccine working after a year.

In both humans and monkeys, researchers found those who received the vaccine still showed signs of the vaccine in their immune system after a year.

Mild side effects were common, and around 1% of people in the trial had more serious adverse reactions to the vaccine.

In the case of the monkeys, one version of the vaccine prevented HIV infection in two-thirds of the monkeys, but this was based on a group of just 12.

This is a really encouraging finding. But this piece of research was designed to test the vaccine's safety and effectiveness at the most basic level.

We don't yet know how well it will protect people from HIV-1 infections in real life. Future trials in people will be needed to show this.

Hopefully, an effective HIV vaccine will become a reality in the future.

In the meantime, you can reduce your risk of contracting HIV by using a condom for all types of sex and by never sharing a needle if you're an injecting drug user.

Read more about HIV prevention

Where does the study come from?

The study was carried out by researchers from a number of institutions, including Harvard University, Massachusetts Institute of Technology, the Walter Reed Army Institute of Research, and the pharmaceutical company Janssen.

The research was funded by Janssen Vaccines & Prevention, the US National Institutes of Health, the Ragon Institute, the Henry M Jackson Foundation for the Advancement of Military Medicine, the US Department of Defense, and the International AIDS Vaccine Initiative.

It was published in the peer-reviewed journal The Lancet.

The UK newspaper headlines were somewhat overoptimistic, as the design of the study means we cannot yet say that the vaccine will truly be effective in people.

The Mail Online placed a lot of evidence on the finding that two-thirds of vaccinated monkeys were protected against HIV infection.

While this was accurate, this was only for the most effective version of the vaccine and was based on results from only 12 monkeys.

What kind of research was this?

This was a randomised clinical trial in which participants received either a vaccine or a placebo injection that appeared the same, but did not contain any active ingredients.

Both participants and researchers were "blinded" to what they'd been given, which meant the results should not have been affected by people making decisions based on what they thought their vaccination status was.

This particular study was a combination of what's known as a phase 1 and phase 2 trial.

These types of trials are designed to test out whether an intervention is safe and works at the most basic level.

In this trial, the researchers decided to carry out studies in humans and monkeys in parallel to make the testing process more efficient.

The next stage would be to carry out a phase 3 trial, where larger numbers of people receive the vaccine.

This is designed to see how effective it really is at protecting people against HIV-1.

What did the researchers do?

The vaccine under investigation in this study was designed to stimulate particular proteins that can interact with HIV and stop it causing a permanent infection.

The researchers looked at several different modifications of the vaccine during the study to test out which might be the safest and most effective.

A total of 393 people were recruited from 12 different centres throughout east Africa, South Africa, Thailand and the US.

All participants were otherwise healthy people aged from 18 to 50 years old who were considered at low risk for HIV-1 infection.

They were randomised to 1 of 8 different study groups, each of which received either a placebo (salt solution) or one of the variations of the vaccination.

People received the injections at weeks 0 and 12 of the study, with boosters at weeks 24 and 48.

The study in monkeys took a similar approach to vaccination, but involved exposing the monkeys to HIV infection on a weekly basis for a period of 6 weeks to see if the vaccine was effective at preventing infection.

This took place 6 months after they'd received all of their vaccinations.

The researchers were looking to see if the vaccines were safe and could be tolerated by people, and whether their immune systems showed signs of activity suggesting the vaccine was active in their bodies after 1 year.

What were the basic results?

Side effects from the vaccination included mild to moderate pain at the injection site, mild to moderate headaches, fatigue and muscle pain.

Only 5 people reported more serious adverse events, including diarrhoea, abdominal pain and dizziness.

There was no particular difference in side effects between people who received different versions of the vaccine.

People's immune systems responded slightly differently to the different versions of the vaccine.

The most effective version showed what's known as a "binding response" of 100% in people at 52 weeks.

This means the person had produced antibodies that would be able to bind to proteins found on the surface of the HIV virus.

More than 80% of people who received this version also showed positive signs for 2 other measures of immune response.

In the monkey study, different versions of the vaccine provided different levels of protection when the monkeys were exposed to a type of HIV that affects apes and monkeys.

The most effective version, given to 12 monkeys, managed to provide protection to 8 of them, while the other 4 eventually became infected.

What did the researchers conclude?

The researchers emphasised the successful findings overall, and for one version of the vaccine in particular.

They mentioned that a further trial (phase 2b) has already been started in South Africa to test whether the vaccine can effectively prevent HIV infection in people.

Conclusions

This is a very promising early finding that provides encouragement that it may be possible to vaccinate against HIV-1.

But it's important to realise that this study was only designed to test whether the vaccine was safe and if it worked at the most basic level, looking at the immune response only.

The researchers deliberately recruited people who had a low risk of HIV-1 infection.

The next planned phase of the study is set to provide the vaccine to 2,600 young women from southern Africa (presumably some of whom may be in high-risk exposure groups) to see if the vaccine can actually prevent people acquiring HIV infection.

We won't know whether this vaccine is effective in a real-world situation until this, and then possibly other later-stage trials, are carried out.

As with most diseases, prevention is always better than cure. A condom is the most effective form of protection against HIV and other STIs. It can be used for vaginal and anal sex, and for oral sex performed on men.