Covishield is the Oxford University - AstraZeneca's candidate in the Covid-19 vaccine race.
Phase two trials are created to test which dose and schedule of a vaccine generates the most antibodies while phase three tests the vaccine's efficacy.
The institute had said that they were not facing any issues in trials on Wednesday. But after being pulled by the drug regulator, DGCI (Drugs Controller General of India), it paused the tests. The outcry was galvanised by the news that AstraZeneca's chief executive disclosed why it had recently halted its vaccine trial - because a person had experienced serious neurological symptoms - at a closed meeting organised by JP Morgan, the investment bank.
In comparison, Oxford's vaccine uses a harmless virus - a chimpanzee cold virus, engineered so it can't spread - to carry the coronavirus's spike protein into the body, which should trigger an immune response. In addition to this, they confirmed that the pause will continue till AstraZeneca restarts the trials.
"The complications are described in the instructions and are predictable", he said.
Serum Institute of India is funding the mid and late-stage human trials for this vaccinate candidate in India.
According to WHO, there are 35 candidate vaccines around the world now undergoing clinical evaluation.
The problem in the UK?
Oxford University, AstraZeneca's partner on the vaccine, has already resumed its clinical trial in Britain, saying in a statement that adverse reactions were an "expected" part of a large trial, the BBC reported. This will be crucial to ensure safety and maintain the integrity of the trials.
Previous studies have shown vaccines delivered by inhalation require lower doses than by injection, which might help stretch limited supplies.
Developers have in recent days begun distributing small batches of Sputnik V across Russian regions in parallel with the Phase 3 trials.
AstraZeneca's trials resumed in the United Kingdom and Brazil on Monday following the green light from British regulators, but remain on hold in the US.
Pfizer also submitted a proposal to the FDA on Saturday (12 September) that would see its late stage trial expanded, including up to 44,000 participants. There has been no confirmation from the concerned authorities in South Africa yet on when the trials will recommence.