The Oxford-AstraZeneca vaccine involves an inactivated common cold virus isolated from chimpanzees, altered with genes to express the spike protein of the SARS-CoV-2 virus.
"Instead of directly injecting the nucleic acid, an RNA or DNA version of that gene, the gene is delivered in another virus," Dr. William Moss, executive director of the Johns Hopkins Bloomberg School of Public Health International Vaccine Access Center, previously said. "They're different strategies to, kind of, trick, if you will, our own body to make the virus protein, release it from the cells, and then our immune system responds to that."
Moss said Oxford-AstraZeneca's vaccine under study is known as a "adenovirus vector vaccine," which, according to the American Chemical Society-published trade outlet C&EN, is a vaccine made with a genetically engineered virus.
When injected, the jab induces an immune response capable of protecting against COVID-19 disease, said a company announcement. After a phase 2 study, researchers said the vaccine invoked a so-called “T cell response” 14 days after vaccination, with an antibody response 28 days later.
This approach is different from that of other companies, like Pfizer and Moderna’s -- whose vaccines operate on a new messenger RNA, or mRNA, platform. The new mRNA technology directly injects the genes for the spike proteins of the SARS-CoV-2 virus into healthy cells to induce an immune response.
All three have announced effective coronavirus vaccines in late-stage trials, with published findings in peer-reviewed journals potentially soon to come.