A group of researchers warned that at least four of the latest batch of new COVID-19 vaccines undergoing clinical trials might make people more vulnerable to catch HIV.
In August, one of the candidates for the vaccine passed its phase 2 trial and is about to undergo a wide phase 3 review in Russia and Pakistan.
The alert came from a team of scientists headed by the University of California San Francisco professor Susan Buchbinder, who directs HIV Preventive Study at the Department of Public Health of San Francisco.
When working to create a vaccine for HIV, the team encountered a related problem first-hand.
To their dismay, despite 20 years of study, their most successful candidate backfired. The result made patients far more susceptible to the disease. Scientists shared their "cautionary" story in The Lancet.
"We are concerned that the use of an Ad5 vector for immunization against SARS-CoV-2 could similarly increase the risk of HIV-1 acquisition among men who receive the vaccine," they wrote.
How clinical trials may cause HIV
Vaccinations need a vehicle of sorts to reach its appropriate sites. This is referred to as a vector and it is this aspect of the vaccine that creates some fear.
Adenoviruses are used as these vectors for some coronavirus vaccine applicants. For example, in one research, a genetically engineered virus supplied the coronavirus spike protein gene code. Hence, one's immune system can learn to identify the spike, and thus SARS-COV-2, as an invader.
Aside from inducing colds, adenoviruses are normally harmless, and other vaccinations have effectively used numerous updated forms of them as vectors without any indication of increased HIV risk.
But a vector named Ad5 (recombinant adenovirus type-5) is used by four candidate coronavirus vaccines, which triggered HIV vaccine issues.
When Buchbinder and her collaborators attempted to do something similar to defend against HIV a decade ago, two experiments resulted in men having an increased chance of contracting HIV, particularly if they had been infected with Ad5 in the past.
While the mechanism behind this is still unknown, one 2008 research indicates that it could have something to do with enhanced immune system activity that creates more cells for HIV to invade.
In 2014, a report led by immunologist Anthony Fauci advised vigilance while utilizing this vector in vaccinations in regions with HIV prevalence.
"This important safety consideration should be thoroughly evaluated before further development of Ad5 vaccines for SARS-CoV-2," The Lancet correspondence concludes.
Vaccine makers remain 'mindful' of these complications
Yet firms who produce these vaccinations have said that they are mindful of this concern and consider the threats.
ImmunityBio told Science that their Ad5 vector was "muted" genetically to reduce the level of immune reaction it causes. They plan to try it next in South Africa if all goes well with their California trial.
Glenda Gray, head of the South African Medical Research Board, who collaborated with the writers of The Lancet's correspondence on the HIV vaccinations, states that avoiding this vector might not be the right option.
"What if this vaccine is the most effective vaccine?" she asked Science. She said that each country's experts must be allowed to make their own decision.
The positive news is that this possibility is being addressed within the science community, and this is the sort of adverse reaction that studies will help us figure out.
They have an incredible reputation of being quite safe after vaccinations have gone through clinical trials. This vigorous research process operated as it could to pick up the vaccine's issues until it was published in the case of Buchbinder's HIV vaccine.
Study teams around the world are working tirelessly to ensure that this is indeed adopted in the production of a vaccine for COVID-19. Several vaccine experiments for a reassessment of safety issues have been halted so far.
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