On July 20, 2020, early human trials of COVID-19 vaccine candidate-- ChAdOx1 nCoV-19 or AZD1222-- developed by the Oxford University and drugmaker AstraZeneca (Anglo-Swedish pharma major), have been published in the medical journal 'The Lancet'. This trial was published a week after the US biotech firm Moderna released its own trial data. Also, amid the surging COVID-19 cases, several firms are racing to find an effective vaccine.
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What do the trials publish in the journal say?
As per the phase I and II trials published in the medical journal 'The Lancet', no serious side effects were noted on the people who were administered the vaccine. The vaccine, however, received antibodies and T-cell immune responses, and the strong responses were recorded with the people who administrated two doses of the vaccine.
A single dose of the vaccine increased antibodies against the spike protein in the first 28 days. The neutralizing antibody responses were detected in 32 out of 35 participants who were administered a single dose and in all 9 participants who were administered a second dose.
The vaccine, however, showed mild to moderate reactions such as fever, chills, muscle aches, headaches and malaise but these were controlled with the help of prophylactic paracetamol.
How does the vaccine work?
By now, everyone has seen the pictorial representation of COVID-19 virus, having spikes on its surface. These spikes are known as 'spike protein' which allows the virus to penetrate cells and thereafter multiply.
The aim of the vaccine is to build the body's immunity against the above-mentioned spike protein. The vaccine belongs to 'non-replicating viral vector vaccines' and is developed to provide antibodies against the spike protein so that the virus doesn't penetrate the cells.
The vaccine developed by the University of Oxford uses a weak version of adenovirus (common cold virus) that infects chimpanzees. The virus is genetically modified and thus will not replicate in humans and will only enter the cell and release the code to make only the spike protein. In turn, the immune system in humans will recognise the protein as a harmful foreign body and will start producing antibodies against it.
Phase III trials of the vaccine
Oxford and AstraZeneca have begun phase III trials in Brazil, targeting 5,000 volunteers. Globally, 160 potential vaccines are underway and 23 of them have been recognised by the World Health Organization for human trials.
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