UCT partners with US company to test efficacy of hAd5 vaccine as a booster shot

Researchers are hoping it proves to be efficient against possible variants that might emerge in future.

FILE: Early data from the local COVID-19 vaccine candidate trial showed that it was safe. Picture: Abigail Javier/Eyewitness News.

CAPE TOWN - The University of Cape Town has collaborated with US immunotherapy company, ImmunityBio, to evaluate the safety and efficacy of its hAd5 COVID-19 vaccine as a possible booster shot.

Researchers are hoping it proves to be efficient against possible variants that might emerge in future.

Early data from the local COVID-19 vaccine candidate trial showed that it was safe.

Co-investigator on the trial, Professor Graeme Meintjes, said 45 participants have been enrolled in the first phase of the study at the research site in Khayelitsha since March this year.

“The first part of the study - the first 20 participants - we were looking to enroll people who had not been vaccinated yet, who had not had COVID and then assessed their immune response to the vaccine, and also assess whether they had any significant side effects from the vaccine, and also whether it was safe in that context,” Meintjes said.

Meintjes explained the second group of participants in the hAd5 vaccine candidate study, included people who previously tested positive for COVID-19 to assess the result of boosting their immunity with the jab.

“And more recently we've enrolled participants who are healthcare workers who were vaccinated with the Johnson and Johnson vaccine. They were enrolled in our study and received the hAd5 vaccine from ImmunityBio, as a booster to the Johnson and Johnson vaccine.”

Phase one of the trial is now closed with researchers performing final analysis before the study progresses into its second phase, which will include 60 participants.

The hAd5 COVID-19 vaccine consists of an adenovirus type-5 vector, used to carry the vaccine into the human body.

Meintjes said genetic sequences of SARS-CoV-2 are inserted into this adeno-5 virus vector.

“In addition, it has a second protein, so it doesn’t have one target of SARS-CoV-2, it has two.”

He said the aim of this dual target approach of regions on the coronavirus was to elicit a broader immune response to the virus in recipients.

“Other aspect of it is the nuclear capsid protein, which is one of these targets presented to the immune system. It has been designed to provide a better T-cell response than other vaccines.”

Other coronavirus vaccines also elicit T-cell responses, but the hAd5 vaccine candidate has been specifically designed to enhance T-cell responses.

The vaccine candidate is being tested at the Khayelitsha and Emavundleni Clinical Research sites in Cape Town.

More research sites countrywide will be rolled out as the trial progresses to Phase 3 that will be coordinated by the South African Medical Research Council.

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