Oxford’s AZD1222 vaccine is made from a genetically engineered virus that causes the common cold in chimpanzees. However, the virus has been modified so that it doesn’t cause infection in people and also to mimic the coronavirus.
Scientists did this by transferring the genetic instructions of the coronavirus’ “spike protein” – the crucial tool it uses to invade human cells – to the vaccine. This was done so that the vaccine resembles the coronavirus and the immune system can learn how to attack it.
Earlier, the Oxford vaccine was tested on monkeys in a small study and had shown some promising results on them. Researchers involved with the ChAdOx1 vaccine trials said the candidate had shown signs of priming the rhesus macaque monkeys’ immune systems to fend off the deadly virus and showed no indications of adverse effects.
Moreover, research by Britain’s Pirbright Institute revealed that a study in pigs has found that two doses of the Oxford vaccine produced a greater antibody response than a single dose.
For phase I in April, 1,102 participants were recruited in multiple study sites in the UK. On May 22, Oxford announced that 1,000 immunisations “have been completed and follow-up is currently ongoing”.
Last month, Professor Adrian Hill, the director of the Jenner Institute at the University of Oxford, told a webinar of the Spanish Society of Rheumatology that the “best scenario” would see results from “clinical trials in August and September and deliveries from October”.