- Initial trials found vaccine induced strong antibody and T-cell responses, which may improve further after booster jab
By Sarah Knapton, Science Editor, The Telegraph (UK), 20 July 2020
Oxford University’s vaccine against coronavirus is safe and produces an immune response, the first human results have shown.
There were found to be no serious adverse events, and minor side effects could be controlled by paracetamol, two papers in The Lancet reported.
The Oxford team has been one of several dozen around the world working on a vaccine since January, when the Chinese first released a DNA sequence of coronavirus.
The inoculation uses a common cold virus, with parts of coronavirus inserted, to act as a Trojan horse and trigger an immune response.
Co-author Professor Sarah Gilbert, of the University of Oxford, said: “There is still much work to be done before we can confirm if our vaccine will help manage the Covid-19 pandemic, but these early results hold promise.
“If our vaccine is effective, it is a promising option as these types of vaccine can be manufactured at large scale.
“A successful vaccine against SARS-CoV-2 could be used to prevent infection, disease and death in the whole population, with high-risk populations such as hospital workers and older adults prioritised to receive vaccination.”
The immune system has two ways of finding and attacking pathogens – antibody and T-cell responses. The Oxford vaccine is intended to induce both, so it can attack the virus when it is circulating in the body as well as attacking infected cells.
The early stage trial found that the vaccine provoked a T-cell response within 14 days of vaccination and an antibody response within 28 days.
Explaining how the vaccine works, the study lead author, Professor Andrew Pollard, of Oxford, said: “The new vaccine is a chimpanzee adenovirus viral vector (ChAdOx1) vaccine that expresses the SARS-CoV-2 spike protein.
“It uses a common cold virus (adenovirus) that infects chimpanzees, which has been weakened so that it can’t cause any disease in humans, and is genetically modified to code for the spike protein of the human SARS-CoV-2 virus.
“This means that, when the adenovirus enters vaccinated people’s cells, it also delivers the spike protein genetic code. This causes these people’s cells to produce the spike protein and helps teach the immune system to recognise the SARS-CoV-2 virus.”
The new trial included 1,077 healthy adults aged 18-55 years with no history of Covid-19, and took place in five UK hospitals between April 23 and May 21.
The participants either received the new Covid-19 vaccine (543 people) or the meningococcal conjugate vaccine (534 people).
All participants gave additional blood samples and underwent clinical assessments to determine whether the vaccine was safe and whether it provoked an immune response.
Participants were also asked to record any adverse events throughout the trial.
Fatigue and headache were the most commonly reported reactions. Other common side effects included pain at the injection site, muscle ache, malaise, chills, feeling feverish and high temperature.
Participants taking paracetamol around their vaccination had reduced pain, chills, feverish feelings, muscle ache, headache and malaise in the two days following vaccination.
In addition, in the 10 people who received the extra dose of the Covid-19 vaccine, side effects were less common after the second dose.
Writing in a linked comment, Assistant Professor Naor Bar-Zeev, of Johns Hopkins Bloomberg School of Public Health, said: “These trial reports are hugely anticipated. The results of both studies augur well for phase three trials, where the vaccines must be tested on much larger populations of participants to assess their efficacy and safety.
“Both trials used adenovirus vectors to deliver and study the Covid-19 vaccine, an innovative and efficient means of vaccine development in the midst of a pandemic.
“Capable of generating humoral, cellular, and innate responses, adenovirus vectored vaccines have much potential.”