Two early coronavirus vaccine trials produce ‘encouraging’ immune responses

21 Jul 2020

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Two vaccine trials in their early stages of testing have returned promising results, with immune responses to the coronavirus present in both.

The Lancet has published peer-reviewed papers detailing the findings of two different early-phase coronavirus vaccine trials that have been described as “encouraging” for triggering strong immune reactions in patients. The first trial involved researchers from the Jenner Institute at Oxford University and the pharma company AstraZeneca while the second was conducted by CanSino Biologics in Wuhan, China.

Both studies reported local and mild side effects to their drugs, including fever and fatigue, but neither reported severe side effects. However, further testing is needed before either vaccine candidate can be released to the wider public. Researchers noted a need to study the vaccines’ effects in older populations and that ethnic diversity in both trials was “very limited”.

The Oxford trial using vaccine candidate AZD1222 involved 1,077 healthy adults (90.9pc of whom were white) aged between 18 and 55. After receiving their dose, a follow-up test 28 days later showed that neutralising antibodies were generated in more than 90pc of participants while T-cell responses were found in all participants.

The strongest immune response was found in 10 of the participants who received two doses of the vaccine. As part of a phase-three trial, the university and AstraZeneca are hoping to conduct a US test involving 30,000 patients, a paediatric study and trials in low-to-middle income countries including Brazil and South Africa, which are already underway.

‘There is more work to be done’

Mene Pangalos, executive vice-president of biopharmaceuticals research and development at AstraZeneca, said: “While there is more work to be done, today’s data increases our confidence that the vaccine will work and allows us to continue our plans to manufacture the vaccine at scale for broad and equitable access around the world”.

Meanwhile, the phase-two trial in Wuhan tested its vaccine in 508 healthy adults aged between 18 and 183 split into two groups receiving either a low or high dose. In their study, the researchers used a weakened human cold virus that had been modified to deliver genetic material to help the immune system recognise and fight the coronavirus. Between 14 and 28 days after receiving their dose, 90pc of patients in both groups produced either a T-cell or antibody immune response.

Responding to these results, The Lancet said the safety signals from these trials are “reassuring”.

“But when things are urgent, we must proceed cautiously,” it said. “The success of Covid-19 vaccines hinges on community trust in vaccine sciences, which requires comprehensive and transparent evaluation of risk and honest communication of potential harms.”

Last week, an experimental vaccine for SARS-CoV2 (the novel coronavirus) developed by the US biotech firm Moderna was deemed to be “generally safe” and provoked an immune response in the first phase of a study published to The New England Journal of Medicine.

Colm Gorey was a senior journalist with Silicon Republic