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Oxford COVID-19 vaccine is made from a genetically engineered virus that causes the common cold in chimpanzees.
Vaccination seems to be the only way to bring the coronavirus pandemic to an end. But when will the world have a vaccine against the novel coronavirus? According to WHO, there are 23 coronavirus vaccine candidates in clinical trials around the world and another 140 in early stage development. Oxford-AstraZeneca vaccine is among the four promising vaccines that are now in the final clinical trials (phase 3). Oxford researchers have published a preliminary report of phase I/II study in The Lancet journal, and it seems like the vaccine is likely to be available this year. These results showed that the injection triggered the production of antibodies and T-cells that can fight coronavirus in the body of the study volunteers. The participants also didn't develop any dangerous side-effects from taking the vaccine.
The phase 1/2, single-blind, randomised controlled trial involving 1,077 people was carried out in five trial sites in the UK. Here are some other key points from the preliminary report of the Oxford-AstraZeneca vaccine trials:
How was the vaccine developed?
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The vaccine - called ChAdOx1 nCoV-19 - is made from a genetically engineered virus that causes the common cold in chimpanzees. It was modified to make it look more like coronavirus and express the SARS-CoV-2 spike protein - the crucial tool it uses to invade human cells.
China-based Cansino Biologics is apparently using the same technology for its vaccine, which has shown "safe" and effective results in the initial trials.
The phase I/II study was carried out between April 23 and May 21, 2020. Around 1077 healthy adults aged 18 55 years with no history of laboratory-confirmed SARS-CoV-2 infection or of COVID-19-like symptoms were enrolled and assigned to receive either ChAdOx1 nCoV-19 or a meningococcal conjugate vaccine (MenACWY) as control.
According to the study results, levels of T-cells peaked 14 days after vaccination and antibody levels peaked after 28 days in the ChAdOx1 nCoV-19 group. T-cells are a type of white blood cell that helps the immune system to identify the infected body's cells and destroy them. Almost all effective vaccines trigger both an antibody and a T-cell response in the body.
Neutralising antibody responses against SARS-CoV-2 were detected in 91% of participants after a single dose. Only ten people were given two doses and all of them developed neutralising antibodies.
"ChAdOx1 nCoV-19 showed an acceptable safety profile, and homologous boosting increased antibody responses. These results, together with the induction of both humoral and cellular immune responses, support large-scale evaluation of this candidate vaccine in an ongoing phase 3 programme," read the preliminary report published in The Lancet on July 20.
Some participants in the ChAdOx1 nCoV-19 group recorded mild side-effects post the injection such as pain, fever, chills, muscle ache, headache, and malaise. The researchers said this could be managed with prophylactic paracetamol. No serious adverse events related to ChAdOx1 nCoV-19 were observed amongst the volunteers.
Researchers are hopeful that phase III trials will see similar results. AstraZeneca has already signed agreements with leading vaccine producers and pharma giants across the world to ensure fast delivery of the vaccine doses if the final trial proves successful. The company is targeting to deliver up to a billion doses before the end of 2020.
Serum Institue of India (SII), which has also partnered with AstraZeneca, may commence its trials soon in India. The institute has released a representative image of the vial of the Oxford vaccine, under the name 'Covishield'.
SII will be applying soon for the licensure trials of Oxford- AstraZeneca vaccine to the Indian regulator.
Adar Poonawalla, CEO, SII, tweeted: "Congratulations to the teams at @UniofOxford and @AstraZeneca for getting this product data out. It all seems to be going well. Hope to get positive results in phase three trials in a few months. We have also hope to start phase three trials in India soon".