Oxford-Astra Covid-19 vaccine shows dual immune action, says researcher

Study shows the vaccine is safe, but it is still too soon to know if it can stop people from being infected

A coronavirus vaccine the University of Oxford is developing with AstraZeneca showed promising results in early human testing, a sign of progress in the high-stakes pursuit of a shot to defeat the pathogen.

The vaccine increased levels of both protective neutralising antibodies and immune T-cells that target the virus, according to the study organisers. The results were published Monday in The Lancet medical journal.

AstraZeneca shares rose as much as 10 per cent in London but gave up some of those gains to trade 2.8 per cent higher as researchers cautioned that the results were preliminary. A positive outcome had been widely expected after reports last week lifted the stock, with the vaccine already in more advanced trials. “We are seeing very good immune responses, not just on neutralising antibodies but of T-cells as well,” said Adrian Hill, head of Oxford’s Jenner Institute, in an interview. “We’re stimulating both arms of the immune system.”

Other vaccine projects, including shots being developed by China’s CanSino Biologics, and a partnership of Pfizer and BioNTech SE also delivered positive trial updates Monday. The results boost optimism about ways to counter a pandemic that’s killed more than 600,000 people and triggered economic turmoil since erupting earlier this year. Moderna, another front-runner, released results last week from an early-stage test that showed its vaccine raised levels of antibodies that fight the virus.

Although stimulating production of neutralising antibodies doesn’t prove a vaccine will be effective, it’s considered an important early step in testing. Results from testing in animals had already shown the Oxford-AstraZeneca shot provoked an immune response.

The Phase 1 trial, which took place between April 23 and May 21, involved 1,077 healthy adults aged 18 to 55 with no history of Covid-19. A control group were given a meningitis vaccine as a placebo and 10 participants received two doses of the shot one month apart. The vaccine caused minor side effects, which could be reduced by taking paracetamol. There were no serious adverse events from the jab.

Most of the participants in the study received a single dose of vaccine. Astra will prioritise a two-shot regimen in future testing, Hill said. Moderna will also test a two-dose regimen. 

A single dose of Oxford vaccine resulted in a four-fold increase in antibodies to the virus’s spike protein in 95 per cent of participants one month after injection, AstraZeneca said in a statement. SARS-CoV-2 uses the spike protein to enter cells.