Vaccine Testing and Trials | AstraZeneca | UPSC

SUSPENSION OF AZD1222

• On Tuesday, the U.K.-based biopharma company AstraZeneca had said it was suspending the Phase-3 global trial of AZD1222.
• The COVID-19 vaccine it has been developing with Oxford University researchers.
• The vaccine, by all accounts, was among the handful that had reached the final stage.

• The pause was announced after a volunteer in Britain fell ill.
• Following a nod from the regulator, trials would resume in the U.K.
• There was no word in the releases about resumption of global trials or details of the volunteer’s illness.

HOW ARE VACCINE TESTED IN TRIALS?

• There are similarities and differences in the way new vaccines are tested.
• Broadly both follow a four-stage process when they are tested in people.

• These animals form mirror human physiology and the way it reacts to diseases — it enters Phase-1 studies.

PHASE 1

• A small group of volunteers is given the drug in small doses.
• Then monitored to see if it is safe and whether it was well tolerated.

• On an average, 10-50 candidates are chosen.
• In the normal course, those undergoing the trial must report results to the drug regulator .
• He is the authority who gives the go-ahead for the next stage of trials.

PHASE 2

• Phase-2 is when a group of volunteers, usually in the hundreds, are selected.

• This is the stage when it’s determined if the inoculation had triggered a desired level of antibodies.
• Thus a sufficient cell response in terms of stimulating T-cells that are known to block and neutralise the virus particles respectively.
• Again, side effects and adverse reactions are monitored and reported.

PHASE-3

• Each of these stages can take several months .

• Such data is again sent to regulators, who, if satisfied, give the green signal for Phase-3.
• In this stage, the drug or vaccine is tested at multiple locations in thousands of volunteers or patients.
• This is the stage when a new drug is compared to the existing standard of care and when it must prove its efficacy.

• A Phase-3 trial is held at multiple locations to capture the demographic variability in the population.
• It is also double-blinded and randomised and may have multiple treatment arms, meaning some participants may get a placebo.
•  Some may get lower doses, some higher doses,

• A diverse population group is exposed to a new vaccine, the odds of encountering adverse and the dreaded ‘severe adverse reaction’ are magnified.
• If severe then, medical researchers have to determine a pattern is apparent, a drug or vaccine can be pulled out.
• Because of the multiple locations and the number of patients that are required, this is also the most expensive stage of a trial.
• Sometimes, phases are combined, given the kind of drug or vaccine and the urgency of the situation.
• Several COVID-19 vaccines are being developed on accelerated time lines.

PHASE-4

• A drug or vaccine candidate that clears Phase-3 is usually approved .
• The licensed and the entire infrastructure of the company is devoted to ramping up production.
• The logistics of storing the drug or vaccine safely is sorted out without degrading or losing potency.

• Phase-4, where all instances of the product’s failure and adverse events are recorded.
• Companies are expected to furnish periodic data to the drug regulator.

WHAT HAPPENED WITH ASTRAZENECA?

• The vaccine candidate, called AZD1222 for now, the company had begun recruiting 30,000 volunteers for Phase-3 trials in the United States.
• The Pune-based Serum Institute of India, which had been contracted to manufacture a hundred million doses for 92 countries including India.
• Serum institute had also started to test the vaccine on a proposed group of 1,600 volunteers in India.
• This led AstraZeneca to pause its trials.