By Mili Jayadeep
A typical vaccine works by inducing an immune response to a pathogen without exposing the body to the full effects of the disease. If the vaccine is successful, an immune response will be triggered resulting in protection against that specific pathogen.
Since the ongoing pandemic, many potential vaccines for COVID-19 are undergoing early trial stages. Currently, there are 23 coronavirus vaccines in early clinical trials and about 140 more in the preclinical stages. However, the oxford vaccine, known as ChAdOx1 nCoV-19 is the first vaccine to prompt a robust immune response to coronavirus infection.
The oxford vaccine results published in the Lancet journal shows a strong immune response is generated following vaccination, which is the key to gaining protection against the virus. The results also do not indicate any serious adverse reactions. However, many participants reported experiencing some mild side-effects including fevers or headaches that could be managed with paracetamol.
ChAdOx1 nCoV-19 is made from a genetically engineered virus that causes the common cold in chimpanzees. The virus has been modified to ‘appear’ like the coronavirus in an attempt to induce a specific response by the body. This allows the body to recognise the similar spike proteins to the actual coronavirus in the engineered vaccine. The body responds as if infected by coronavirus itself.
In other promising trials that are underway, such as that by the Valneva company, inactivated coronavirus is being developed into a vaccine.
The results for the oxford vaccine based on around 1077 people show encouraging results as it generated neutralising antibodies against coronavirus and T-cells, which is the signature of the defensive immune response by the body. In the case of infection with the real virus, the body recognises the virus due to the presence of these antibodies hence offering a quicker defence against infection. T-cell produced are also involved in the immune response owing to its role in attacking infected cells as well as stimulating other immune cells. Successful vaccines have been those inducing both these responses.
According to Professor Andrew Pollard, from the Oxford study:
“We’re really pleased with the results published today as we’re seeing both neutralising antibodies and T-cells. They’re extremely promising and we believe the type of response that may be associated with protection.”
The study showed that neutralising antibody production was observed in the majority of participants and double the dose resulted in a better immune response, suggesting this could be considered if this vaccine were to be officially administered. Professor Pollard says:
“We saw the strongest immune response in the 10 participants who received two doses of the vaccine, indicating that this might be a good strategy for vaccination,”
Although the results offer great promise, more research is necessary before the vaccine can be developed for distribution. In the UK, over 10,000 people will be partaking in the next stages of trials. Results will also be collected from Phase 3 clinical trials occurring in Brazil and South Africa to test the effectiveness of the virus in areas with greater cases of coronavirus in the population.
The government has funded a vaccine development project with £84m to help progress. AstraZeneca is the pharmaceutical company working in collaboration with Oxford university to investigate wide-scale production and distribution of this potential vaccine.
Based on the results of this study, the vaccine could potentially be distributed by the start of next year if the next stages of the study prove to be successful. Professor Pollard informs, “But the key question everyone wants to know is does the vaccine work, does it offer protection… and we’re in a waiting game.”