Oxford’s vaccine candidate promising
Strong immune responses reported
LONDON – Two candidate vaccines, including a closely watched one being developed at the University of Oxford, showed positive trial results Monday against the virus that causes COVID-19, making it more likely that a safe, effective vaccine can be developed quickly.
They add to two small, previous studies on different vaccine candidates in the U.S. that also appeared to be relatively safe and to trigger appropriate immune responses in study subjects.
Early stage trials explore only safety and dosing and cannot determine a vaccine’s effectiveness, but signs indicate that all four candidate vaccines are leading to immune responses similar to those experienced by people infected with the SARS-CoV-2 virus.
About 17 candidate vaccines are being tested in people around the world.
The new results showed Oxford University and drug company AstraZeneca’s candidate vaccine, AZD-1222, led to strong immune responses for nearly two months in a trial that continues to track more than 1,000 healthy adults. A second dose, given to 10 patients, seems to have boosted their immune response further without adding significant side effects, according to a paper published Monday in The Lancet.
“I think it’s very exciting,” Barry Bloom, an immunologist and global health expert at the Harvard T.H. Chan School of Public Health, said Monday on a call with media. “The unlikely possibility that we will have vaccines ready for approval and large-scale distribution by the end of the year – which seemed utterly crazy seven months ago – may well be a real possibility.”
He and others Monday emphasized that the process is being sped up not by cutting corners on safety but by conducting research steps simultaneously that are typically done sequentially. Oxford-AstraZeneca’s trial is considered a Phase 1-2, and the pair is already getting ready to launch a large-scale Phase 3 trial within a few weeks.
Pascal Soriot, CEO of AstraZeneca, said Monday that he was pleased with the results.
“So far so good in terms of the data we’ve produced,” he said. “All this needs to translate into clinical protection. People need to be protected from infections, and that’s what we want to demonstrate in our Phase 3 program.”
The next stage of trials in Britain will involve 10,000 people. In the U.S., 30,000 people will take part. And in Brazil and South Africa, about 7,000 people will test the efficacy and safety of the vaccine. If everything goes to plan, the vaccine could be rolled out widely by early next year, according to the Oxford Vaccine Group.
Soriot expects 50,000 will be vaccinated in clinical trials this year.
The Oxford-AstraZeneca vaccine uses a weakened chimpanzee cold virus to carry a protein from SARSCoV-2 into human cells. Once there, it triggers the person’s cells to produce the spike protein found on the surface of SARS-CoV-2, causing the immune system to attack the virus.
The second study published Monday in The Lancet looked at a Chinese vaccine candidate tested in more than 500 people, including a small number older than 55. The goal of the study was to evaluate the immune response and safety of the vaccine and determine a dose that would be used in a larger Phase 3 trial.
The Chinese vaccine candidate works almost the same way as the Oxford-Astra Zeneca one, but it uses a weakened version of the human common cold virus to deliver the SARSCoV-2 protein. Half of the trial participants were already immune to the human cold virus, which is expected to limit the vaccine’s effectiveness.
Academic researchers who specialize in vaccine development said Monday that both studies are promising, but they’re waiting for more results before declaring victory over COVID-19.