How far are we from an HIV vaccine?

By Hilary Bainemigisha

Today is HIV Vaccine Awareness Day, an opportunity to recognize and thank the many volunteers, community members, health professionals, and scientists who are working together to find a safe and effective HIV vaccine.

According to Prof. Anthony Fauci, a director in the US National Institutes of Health (NIH), scientists are more optimistic than before. A breakthrough in getting a vaccine for HIV will be the final blow to the virus if the vaccine is effective, safe, affordable and accessible to all. A vaccine would be better than all preventive technologies being studies and processed because it is taken once for a lasting protection. It would have no adherence issues, Fauci says.

When is the vaccine coming
Bill Gates, the founder of Microsoft and one of the big funders of HIV research predicted that the HIV vaccine should be available by 2030. And that it would be the end of the virus that has killed millions in the past three decades.
"When we reach that point, cases will start going down everywhere around the globe for the first time since the disease was discovered more than 30 years ago," Gates said. "We may not see the end of AIDS, but both for malaria and AIDS, we're seeing the tools that will let us do 95-100% reduction."

However, doctors close to research are uncomfortable with a specific time period. It can be longer and it can be shorter, they said. What matters is that people continue using all the available prevention technologies to avoind HIV infection.

Achievements so far

Gates expects the vaccine in 15 years because he is excited by the many trials going on in many countries. Researchers are trying new candidates, new systems, new technology and a host of others are learning from trial results details about our immune system and the virus.
In all these, two developments do stand out as the future hope for an HIV vaccine.
The Thai trial

The biggest success in HIV vaccine development so far has been the large-scale study among 16,000 volunteers in Thailand, which demonstrated, for the first time, that an HIV vaccine can provide about 31% level of protection. It was published in 2009. Unfortunately, this is not enough protection to warrant licensing because public health experts generally want a vaccine to protect at least 70% to 80% of people vaccinated.

Researchers are therefore following up on this study with other trials using an improved Thai vaccine regimen, altered to see if it can be more protective and longer-lasting. The trial, called HVTN 100, is going on in South Africa and the US. If all goes well, the next phase will be another larger trial beginning in late 2016 or early 2017. Dr. Linda-Gail Bekker, who is leading the South African trial, believes it could lead to the first licensed HIV vaccine. She is deputy director of the Desmond Tutu HIV Centre at the University of Cape Town.

Broadly neutralizing antibodies

On its own, the human body finds difficulty combating HIV because the virus quickly mutates into many strains. Science estimates that they are about 195 to 237 HIV strains so far. An ideal HIV vaccine needs to induce antibodies which can destroy a broad range of HIV strains. Already, these are being produced naturally by approximately 25% of chronically HIV-infected people. The problem is that these broadly neutralizing antibodies don't appear until very late in the infection. Now researchers are trying to trigger the body to produce them earlier in the infection.

Researchers are also trying to isolate the broadly neutralizing antibodies from AIDS patients in order to use their molecular structure to design immunogens (substances that are capable of generating antibodies) that mimic them. Then they would immunize volunteers with these mimics to try to elicit the desired antibody response. Early data from monkey studies suggest that such direct injection of broadly neutralizing antibodies may also have therapeutic benefits or even be part of a multifaceted HIV cure strategy.

In Uganda
Uganda was the first in Africa to launch an HIV vaccine trial in 1999 at the Joint Clinical Research Centre (JCRC). The second came in 2003 at Uganda Virus Research Institute (UVRI). According to AVAC website, there are over seven trials taking place at IAVI, Makerere University Walter Reed Project (MUWRP), and Institute of Infectious diseases.

"We are pleased that Uganda continues to play a leading role in the testing of promising HIV vaccine candidates," said Dr. Pontiano Kaleebu,  Director, MRC/ Uganda Virus Research Institute. "A vaccine is the world's best hope to end the spread of a disease that infects 14,000 men, women and children worldwide every day."

Is there hope?
For 27 years, HIV vaccine trials result after result, even of very promising investigational candidates, have disappointed. However, there is no failure in the science world, Dr Patrick Ndase, a reknown researcher in HIV studies always says. These trials may have a failed candidate, but they leave in the hands of scientists a wealth of information and knowledge about the HIV, our immunity and the different medications.  

But a HIV vaccine is possible. In concepts, laboratory work and animal trials, vaccine candidates demonstrate exciting success. Thus scientists are a step away from making them work in humans.

True, it has taken long to get a vaccine for HIV with little success. But that is not surprising. HIV was identified in 1983. It took 47 years to develop the polio vaccine! The research community agrees that it is getting closer than ever before.
An HIV vaccine is very vital in the end of AIDS. Over the years, deadly epidemics have not been curbed by drugs but vaccines. Vaccines eliminated smallpox worldwide and polio to a wide extent.

Problem of HIV vaccine

Scientists still don't understand how to elicit specific, durable, and protective immune responses against HIV. Animal models, while informative, can only hint at what works.

This means HIV vaccine researchers need to be as wily as the virus.

HIV kills the very immune cells used in defending the body against it. It mutates rapidly within individuals and across geographical locations, making it a moving target for vaccines.

Developing vaccines against measles and other diseases was relatively straightforward when compared with the process scientists must use today to fight HIV.

This virus is much more complex and difficult to combat because it furiously mutates its shape and has produced multiple subtypes, allowing it to confuse the immune system response.

Researchers cannot use a weakened HIV to immunize people because it is unethical. So they use a replica which does not react the way HIV would.

The virus also hides in reservoirs from which it can strike again at any time. Many people actually respond to HIV attack and fight it seriously to recover from the initial infection.

However, not a single person infected with HIV has cleared the virus on his or her own.

Your role

The search for a vaccine is not the work of researchers and donors. Everybody is needed especially as volunteers.

You cannot get an HIV infection from taking part in research as a volunteer. Scientists use synthetic (man-made) genes which make proteins that resemble those that are present in a real virus, but they do not contain the information required to cause HIV infection.

Before the study, a clinician will answer all the questions you have. You are encouraged to take your time in coming to a decision to participate in a vaccine trial, so that you are comfortable and fully informed before enrollment. You can even withdraw from the study at any time without any negative consequences.

Conclusion

Of course success is needed sooner. UNAIDS says about 2 million people worldwide contracted HIV in 2014, some 1.6 million died of AIDS related complications, bringing the total of people who have died of AIDS, since it was identified in 1983, to over 40 million.

The world needs an effective, affordable and acceptable vaccine sooner.

Related

The quest for an AIDS vaccine: A timeline

Experts urge renewed push on US-Thai HIV vaccine