The Oxford-AstraZeneca candidate has been the most promising of the over 200 vaccine candidates in works, as we scramble to find a way out of the novel coronavirus pandemic.
The vaccine has been one of the most successful candidates, undergoing phase-3 clinical trials at more than 60 locations in the US, Brazil and South Africa. However, the potential vaccine grabbed headlines earlier this month after it stopped trials and resumed it a few days later in a few countries.
Why exactly was it stopped and restarted? Here’s all you need to know.
Why was the Oxford-AstraZeneca vaccine trial halted?
On 6 September, AstraZeneca announced that a vaccine candidate triggered a “voluntary pause to vaccination” across “all global sites”. It added that this would enable independent committees and international regulators could review safety data related to the vaccine.
While the exact incident that triggered the response has not been revealed by the company, it was widely reported that neurological symptoms developed by one candidate resulted in the halting of trial.
How did the pause impact the trial?
The impact of the pause is difficult to ascertain as it was resumed in UK just days after, on Saturday, 12 September. However, it is yet to begin in many other countries.
In a statement, the company said that it will work with health authorities “across the world” and “be guided” as too when other clinical trials can resume.
It was the first to go into phase-3 human trials; the phase 1/2 preliminary results have largely been promising, generating both antibody and T Cell response in participants.
What about India? Have the trials resumed?
The vaccine is being tested in Pune-headquartered Serum Institute of India (SII) and was put on hold, following UK's decision to do so.
According to Indian Express, SII told Dr VG Somani that the Data Safety and Monitoring Board (DSMB) that it was looking into follow up data from the first set of volunteers vaccinated in India “noted no safety concerns”.
At least 100 candidates have received the vaccine in India.
Does this usually happen with vaccines that are on trial?
In a normal scenario, the halt of an ongoing trial would have been a routine event.
"In all large randomised efficacy trials of an investigational drug or vaccine, the drugs are given to a large heterogeneous population. Some of these people also have underlying health conditions and they may react adversely. This is exactly why we need large trials before approval," says Dr Shahid Jameel, virologist, and director, Trivedi School of Biosciences at Ashoka University.
He adds this is also not uncommon in such trials, saying, "The good thing is that there is a system in place to recognise these adverse events and address them. This is good and will build confidence in the trials."
Dr Giridhar Babu, a Bengaluru-based epidemiologist also agrees with Dr Jameel.
“This is actually a relief, because it means due process is being followed and we are not rushing through the trials.”Dr Giridhar Babu, Epidimeologist told FIT
When are we likely to get a COVID-19 vaccine?
The World Health Organisation also made a very clear statement saying no large scale vaccination is likely until before mid-2021. "This phase 3 trials must take longer because we need to see how truly protective the vaccine is and we also need to see how safe it is," said Margaret Harris, a WHO spokesperson.
(With inputs from FIT)
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