Bare Truth by Rose de la Cruz
Bare Truth

After 40 years, still no vaccine for HIV

Jun 9, 2021, 3:12 AM
Rose De La Cruz

Rose De La Cruz

Columnist

IS it because the severe acute respiratory syndrome (SARS) that caused the coronavirus disease (SARSCoV2) which we now call COVID-19 (from 2019 when it started) being very virulent and infectious, that global scientists rushed to find its cure that we now have vaccines for COVID-19, and none for HIV -AIDs (human immuno-deficiency syndrome-acute immune deficiency syndrome)?

Yet, the vaccines for COVID-19 were developed in record time and have shown remarkable levels of safety and efficacy, helping drive down caseloads in the countries fortunate enough to have wide access.

Many of these shots were developed using technologies that were previously being tried out on HIV -- so why haven't we had breakthroughs yet?

These questions crept in my head on seeing the AFP story about why there is yet no vaccine for HIV, which affects 38 million globally after four decades.

In the four decades since the first cases of what would come to be known as AIDS were documented, scientists have made huge strides in HIV treatment, transforming what was once a death sentence to a manageable condition.

What we still do not have is a vaccine that would train human immune systems to ward off the infection before it ever takes root.

Access to medications

Why do we need an HIV vaccine?

More people than ever now have access to medications called antiretroviral therapy or ART, which when taken as prescribed, keeps down the amount of virus in their body.

This keeps them healthy and unable to transmit HIV to their partners.

Beyond ART, people at high risk for infection can now get pre-exposure prophylaxis, or PrEP, a pill taken every day that reduces the risk of infection by 99 percent.

"But access to medication is not organized in every part of the world," Hanneke Schuitemaker, global head of viral vaccine discovery at Johnson & Johnson's Janssen Vaccines, told AFP.

Disparities exist

Even within wealthy countries, wide socioeconomic and racial disparities exist in accessing these medicines, and vaccines have historically been the most effective tools to eradicate infectious diseases.

J&J is currently carrying out two human efficacy trials for its HIV vaccine candidate, and initial results from one of them may come as early as "the end of this year," Schuitemaker said.

Challenges

"The human immune system doesn't self- cure HIV, whereas what was very clear was the human immune system was quite capable of self- curing Covid-19," Larry Corey, principal investigator of HVTN, a global organization funding HIV vaccine development, told AFP.

Covid vaccines work by eliciting antibodies that bind to the virus' spike protein and stop it from infecting human cells.

HIV also has spike-shaped proteins on its surface, which are the target of HIV vaccine development.

But while Covid has tens of well- known variants circulating worldwide, HIV has hundreds or thousands of variants inside each infected person, William Schief, an immunologist leading development of an mRNA HIV vaccine at Scripps Research Institute said.

Because it is a "retrovirus" it quickly incorporates itself into its host's DNA. An effective vaccine will need to stop the infection dead in its tracks, not just reduce the amount of virus and leave the remainder to stay with the person forever.

Where we stand

Efforts to develop a vaccine have been going on for decades but none has come to fruition.

Last year, a study called Uhambo that was taking place in South Africa and involved the only vaccine candidate ever shown to provide some protection against the virus, was ultimately not effective enough.

J&J's vaccine candidate is currently being trialed in 2,600 women in sub-Saharan Africa in the Imbokodo trial, which is expected to report results in the coming months.

It is also being tested in around 3,800 men who have sex with men and transgender individuals across the United States, South America, and Europe in the Mosaico trial. Initial data for this could come in 2024.

The J&J vaccine uses similar adenovirus technology to its Covid-19 vaccine, in other words a genetically modified cold virus delivers genetic cargo carrying instructions for the host to develop "mosaic immunogens" -- molecules capable of inducing an immune response to a wide variety of HIV strains.

This is followed up by directly injecting synthetic proteins in later doses.

Another promising approach is to try to generate "broadly neutralizing antibodies" (bnAbs) which bind to areas of the HIV virus that are common across its many variants.

The International AIDS Vaccine Initiative and Scripps Research recently announced results early on staged trials showing their vaccine candidate stimulated the production of rare immune cells needed as a first step in the process of inducing bnAbs.

They hope to move forward to further develop their vaccine with mRNA technology in collaboration with Moderna.

The strategy, explained Schief, is to use a sequence of shots to try to gradually educate antibody producing B-cells. They also hope to train up another kind of white cell, known as T-cells, to kill any cells that still get infected despite the antibodies.

Efficacy trials are still a long way off, but he is hopeful the mRNA technology, which turn the body's cells into vaccine factories and has proven its worth against Covid-19, can make the difference.

HIV-AIDS in the Philippines

According to the DOH HIV/AIDS and ART Registry of the Philippines (HARP), there are now a total of 81,169 HIV and AIDS cases reported from January 1984 to October 2020. In October 2020, there were a total of 735 confirmed HIV-positive individuals. Ninety-six percent (704) of whom were male.

Among the total 81,169 diagnosed cases from January 1984 to October 2020, 94 percent (76,216) were male and more than half (51 percent, 41,163) were 25-34 years old at the time of diagnosis.

Of the 81,169 cases, the bulk of reported cases were in NCR with 30,622 cases (38 percent), CALABARZON with 12,467 (15 percent), Central Luzon with 8,005 (10 percent), Central Visayas with 6,827 (8 percent), and Davao Region with 4,477 (6 percent).

Health workers, civil society organizations, people living with HIV, and various agencies all play a vital role in eliminating stigma and discrimination, as well as providing accessible testing, treatment, care and support for People Living with HIV.

“Despite the presence of the COVID-19 pandemic, we should all remain focused and resolute in our mandate of preventing and reducing transmission,” Health Secretary Francisco T. Duque III said, adding that an average of 21 new cases are now reported in the country daily.

Sec. Duque explained that the 21 new HIV cases diagnosed every day means that the country is facing a public health threat which needs the continuing cooperation and collaboration of all local communities, civil society organizations, key populations at risk and the whole of government.

The government must continue to provide quality HIV and AIDS-related services that are readily available including addressing conditions that aggravate the spread of HIV infection which include poverty, gender inequality, marginalization and ignorance.


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