The University of Oxford COVID-19 vaccine explained
How does the Oxford COVID-19 vaccine work?
The Oxford COVID-19 vaccine has been developed using a method which was previously used to create a vaccine for another coronavirus, Middle East Respiratory Syndrome (MERS). The vaccine was shown to induce a strong immune response, meaning it would be likely to create immunity in those who received it. The MERS Oxford vaccine has not yet completed the clinical trials stage due to falling infection rates.
Like previous vaccines produced by the same institute, the ChAdOx1 nCoV-19 vaccine from the University of Oxford is made using an adenovirus. This is a milder virus with symptoms much like a common cold, which is manipulated so it cannot reproduce within the body and so it holds the genetic instructions to teach the body how to create coronavirus antibodies. The vaccine induces an immune response which creates the necessary antibodies that the body needs to fight coronavirus, creating immunity in the patients who receive it.
What is the current stage of development?
The Oxford vaccine is currently in the clinical trials stage of development, which is when groups of volunteers are given the vaccine in order to determine its safety and effectiveness.
Every vaccine must go through a number of different stages in development, usually starting with the exploratory stage, before moving on to the pre-clinical stage, which involves testing the vaccine either in a laboratory or on animals. Once the vaccine is determined to be safe to test on humans, and has a good chance of creating immunity, it can then be tested on humans.
In the case of the Oxford COVID-19 vaccine, after preliminary testing on animals, development went into to the human trials stage. Additional pre-clinical testing is being conducted in parallel with clinical trials.
Animal testing results
In addition to the vaccine being tested on groups of volunteers, tests have been made on rhesus macaques, which are considered to have a similar immune response to humans. The findings (which have not yet been peer-reviewed) showed that after being given one dose of the vaccine, this “significantly reduced viral load” in the monkeys, and they were protected from contracting coronavirus-related pneumonia in the lungs. However, they also still had just as much coronavirus genetic material in their noses as unvaccinated monkeys, meaning that all of the vaccinated and unvaccinated monkeys were infected with COVID-19.
This could be for a number of reasons. It has been suggested by Dr Sarah Gilbert, one of the lead researchers developing the vaccine, that the high levels of coronavirus molecules present in the noses of the monkeys could be due to the fact that they received very high doses of the virus. It is also unclear as to whether the virus particles found in the noses of the monkeys were actively infectious, as they could also be “inactivated” byproducts of the body’s immune response.
Alternatively, it has been suggested that the vaccine can only produce immunity in the lungs, but not in the mucous membranes in the nose. According to some immunology experts, this has been the case with previous coronavirus vaccines.
It is impossible to tell for certain if the Oxford COVID-19 vaccine works until the full results from the clinical trials have been released and reviewed.
Human trial stage
Clinical trials are usually made up of three different phases. In phase I, small groups of volunteers receive the vaccine to ensure it is safe. In phase II, the effectiveness of the vaccine is determined with a larger group of volunteers. In phase III, an even larger group of volunteers receives the vaccine, which tests the effectiveness and safety of the vaccine on a diverse group of people of different ages and backgrounds. This ensures that the vaccine will work for everyone.
The Oxford COVID-19 vaccine was one of the first in the world to begin testing on groups of volunteers. Starting in April, combined phase I and II testing began when more than 1,000 volunteers received the experimental vaccine in the UK. Falling levels of coronavirus infection means that the phase II/III of clinical trials are also underway in other countries.
Trials for the Oxford vaccine are currently taking place in the UK, Brazil, South Africa, Japan, and Kenya.
When will the Oxford vaccine be ready?
The scientists developing the coronavirus vaccine at the University of Oxford’s Jenner Institute initially said that their vaccine candidate could be ready by September. However, falling infection rates in the UK meant that clinical trials could not be completed by the end of the summer as planned.
AstraZeneca, the biopharmaceutical company working with scientists at Oxford University to produce the vaccine, began manufacturing doses of the vaccine during the summer. AstraZeneca has committed to delivering 400 million doses of the vaccine by the end of 2020, ready for distribution once the vaccine completes clinical trials and has been given regulatory approval.
Plans for the distribution of the vaccine have been made, but cannot begin before the clinical trials have been completed. Professor Andrew Pollard, the chief investigator of the trial, told the UK government’s Science and Technology Committee that there is a “very small chance” that the vaccine will be ready for distribution before Christmas.
Analysis must first be made of the data from the clinical trials taking place all over the world before it can be determined that the vaccine is effective. Initial reports suggest that the vaccine provokes a strong immune response among the elderly, as well as young adults.
Before the coronavirus vaccine is ready it must go through a number of stages in development. Take a look at our coronavirus vaccine tracker for the latest news and results on vaccines in each stage.