• Sunday, December 03, 2023
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Here’s why HIV can’t find vaccine 40 years after but COVID-19 can in 10 months

Delta to include persons living with HIV/AIDS in empowerment programmes

By 2021, it will be 40 years since the human immunodeficiency virus (HIV) was identified without breakthrough on vaccine or cure.

But in 10 months, the COVID-19 pandemic has found at least one approved vaccine from a basket of seven selected candidates in phase three of clinical trials and more than 150 in preclinical development.

Researchers’ best bet for HIV has been to suppress the virus in infected individuals and prevent new infections mostly through enlightenment on the risks of exposure.

Deborah Birx, U.S. Global AIDS Coordinator and Special Representative for Global Health Diplomacy Ambassador, described the case of HIV as a very different one that has not produced an outcome where people recovered naturally.

People have not been able to develop correlates of protection that can build immunity effective enough to clear the virus leading the direction to a vaccine path. In essence, people do not recover but basically manage the disease.

“And because the only people who have been cured of HIV are those individuals that had bone marrow transplants, which of course is not a vaccine, it’s made vaccine development much more difficult,” Birx said during a digital press briefing on Tuesday.

“But I have every confidence and see the work coming out of NIH and research communities around the globe, and no one has stopped working on HIV vaccines or doing those clinical trials for HIV,” Birx said.

Over 17 million people including men, women, and children under the US President’s Emergency Plan for AIDS Relief (PEPFAR) antiretroviral treatment have to ingest drugs daily to stay healthy for themselves and others.

For COVID-19, studies into immune reaction to the virus indicate that antibodies as well as immune cells that identify the virus persist months after the infection has been resolved. This is unlike the case with HIV.

Even new findings reinforcing this say that people who have recovered from COVID-19 still have enough immune cells to wade off the virus eight months after, preventing illness.

The mechanism some of the leading pharmaceutical firms racing to develop a vaccine for COVID-19, such as Pfizer, have devised is to attack the protein spikes which enable a virus to invade human cells and start infection.

The attack happens by triggering cells to produce the proteins, leading to the production of antibodies once an individual gets a shot of the vaccine.

Through a biotechnology named mRNA, researchers are now able to instruct the body cells to build proteins found specifically in SARS-CoV-2, the virus that causes COVID-19.

According to Pfizer, in the tests conducted so far, 90 percent of those who got its vaccine produced antibodies that recognise the proteins in COVID-19.

The company is only one of 40 candidate vaccines for COVID-19 in clinical evaluation.

For HIV, the certainty of cure remains heavily researched and debated.

Jennifer Zerbato and Sharon Lewin, in an article published on The Lancet HIV, probe the length of time at which an individual can be considered cured after transplantation and halting of antiretroviral treatment.

Citing the work of Ravindra Gupta and colleagues with extensive tissue and blood sampling of a London patient whose HIV RNA plasma has remained undetectable for 30 months, they query whether the strategy could count as a cure.

The London HIV patient was diagnosed with Hodgkin disease and received a stem-cell transplant from a donor who carried a mutation in the CCR5 gene. CCR5 is a key receptor for most strains of HIV, implying that macrophages that do not express CCR5 are protected from infection with strains of HIV that use this receptor.

Macrophages are a type of white blood cell that surrounds and kills microorganisms, removes dead cells, and stimulates the action of other immune system cells.

“The finding of no intact virus in both blood and tissue can be reassuring for a patient who might face great anxiety and uncertainty about whether and when a viral rebound off ART might occur, which in other settings has been completely unpredictable. In view of the many cells sampled in this case, and the absence of any intact virus, is the London patient truly cured?” Zerbato and Lewin ask.