THE VACCINE - ChAdOx1 nCoV-19, now known as AZD1222, was co-developed by the University of Oxford and one of its spin-off companies,
Recently we wrote a blog on the success of an RNA vaccine against SARS-CoV-2, the virus responsible for COVID-19. Within just a few weeks of that incredible research breakthrough, researchers at Oxford University’s Jenner Institute have announced a COVID vaccine that has induced remarkable immune response against the virus.
This study was published in the Lancet, one of the most prestigious medical journals in the world, and a simple summary suggests the vaccine has no early safety concern and is able to induce a strong immune response with both T cells and B cell/antibodies.
ChAdOx1 nCoV-19, now known as AZD1222, was co-developed by the University of Oxford and one of its spin-off companies, Vaccitech. The vaccine uses a viral vector based on a common cold virus (adenovirus). This carries genetic material for the SARS-CoV-2 spike protein. In our previous blog, we saw how the spike proteins are used by the virus to target and fuse with our target cells, allowing the virus to invade, replicate and ultimately cause the disease known as COVID. It is also a good target for the human immune system to recognize and attack.
The viral vector delivers the genetic material inside our cells. The spike protein is then produced by our cells, recognized by the immune system as a viral target, and an immune response is created against it. This can be antibodies, which recognize, attach to and mark the virus in our blood, allowing for other white blood cells to destroy the virus.
In this case, the vaccine also produced a T cell response. T cells can recognize cells infected by a virus-based on the markers present on the surface of infected cells. They can tell an infected cell to destroy itself, thereby destroying the virus within without spreading the infection. They also have other functions that we will not discuss in this blog.
This study was a Phase I/II trial that started in April using the vaccine named ChAdOx1 nCoV-19. This vaccine development started in January 2020, and progress on development has been incredibly rapid. Whilst our previous study had just 45 people, this study looked reviewed over 1,000 healthy adults. 10 of these participants received two doses of the vaccine.
In a study the more participants there are, the greater the power of the study. If the vaccine has any side effects, even ones that rarely occur, it is more likely to be picked up in studies with more people. Similarly having more people helps show that the vaccine is effective, and the strong responses are not merely a fluke or accident. Another benefit of this study is it was able to compare the vaccine against a control group. This shows the results were not simply a placebo and allowed comparison of side effects as well.
The majority of side effects were feeling feverish, chills, muscle ache, headache, and malaise, all symptoms treatable with paracetamol. None of the participants had any serious side effects. It took just 14 days to create a T cell response, and 28 days to make strong antibodies. In 91% of patients, this was enough to neutralize the COVID coronavirus. Receiving two doses gave an even stronger antibody response, and all participants were able to stop the virus.
The news from the University of Oxford is needed, as infection rate and mortality continue to increase in countries such as the US and Brazil. The ability to induce an antibody response without causing harm to the patient shows we have made huge progress in the fight against COVID-19. Further Large scale Phase III trials been set up through a global partnership, and include studies in the US with over 30,000 patients, studies in children as well as some in low to middle-income countries.
If successful a vaccine would be essential in preventing a second wave of COVID in the winter when the elderly population is most at risk. And it would be the key to restarting the economy and getting our everyday lives back to where it was pre-pandemic.
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