Could some of the COVID-19 vaccine candidates make people more vulnerable to HIV?

COVID-19 vaccine risk of HIV
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Four prominent COVID-19 vaccines currently in development could increase the risk of HIV, according to a report published in medical journal The Lancet

The vaccines in question use a modified virus called adenovirus 5 (Ad5) as a vector to administer the protein gene SARS-CoV-2—the viral cause of the coronavirus—into the body. 

Scientists are concerned because Ad5 was found to increase the risk of HIV when it was used in advanced experimental vaccine trials to treat the AIDS virus in 2007. Those trials, called STEP, led to the discontinuation of the AIDS vaccine made by Merck. Scientists found a relationship between Ad5 and increased AIDS risk. 

Four of the scientists involved in the STEP trails led the authorship of the recent report from The Lancet. They view STEP as a “cautionary tale” to be seriously considered in the development of coronavirus vaccines. 

Most vaccines work by administering altered versions of a virus into the body. In best-case scenarios, the most harm these viruses cause is a common cold. The Lancet editorial warns of several potential consequences from Ad5 in COVID-19 vaccines, including weakening HIV immunity, enhancing replication of the AIDS virus, or setting up more target cells for the virus.

Ad5 is an active ingredient in four prominent COVID-19 vaccines in development around the world. Two of these are in large scale 3 trials in Russia and Pakistan, where researchers hope to eventually administer to more than 40,000 people. Experts are particularly concerned about Ad5 vaccine trials happening in sub-Saharan Africa countries, such as South Africa, where large HIV epidemics have broken out in the past. 

“If I were in a sub-Saharan African country and making a decision as to what I would want for my country for a general population use of a SARS-CoV-2 vaccine, I don’t see why I would pick an Ad5 vector [vaccine] when there are many other alternative choices,” Lawrence Corey, one of the authors who now co-leads the COVID-19 prevention network, said. 

Others are hesitant to rush to conclusions from the STEP study. Patrick Soon-Shiong, CEO of ImmunityBio, called the results “very, very fuzzy.” ImmunityBio recently received approval from the U.S. Food and Drug Administration to begin human trials of its COVID-19 vaccine, which uses Ad5 as a vector. Soon-Shiong doesn’t see it as a risk because ImmunityBio’s Ad5 has four deleted genes that reduce the immune responses it triggers. “It’s 90% muted,” he said.

Pediatrician Glenda Gray, who also co-authored The Lancet report, is at a crossroads. “What if this vaccine is the most effective vaccine?” she said. “If this works out to be an important vaccine, we’ll have some experience with it.”

The medical consensus has landed on a need for considerably more research and literature before vaccines using Ad5 can become a realistic option for the general population.

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Sources: ScienceMag, The Lancet

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