Vaccine Testing and Trials | AstraZeneca
Why is Phase-3 of vaccine trial complicated?
WHY IN NEWS:
With University of Oxford and AstraZeneca announcing resumption of COVID-19 vaccine trials, how will the process be monitored for safety?
SYLLABUS COVERED: GS 3:Health:Diseases : Vaccine
For PRELIMS go through all the different phases of testing . Note one key point from each phase in your Prelims Book.
For MAINS it is important to understand the whole process . Let us dive in !
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.
- 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 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.
- 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.
- 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.
- Serum Institute initially said it would not halt the India trial because no adverse reactions had been reported here.
- However, after a show-cause notice from the regulator, the Drugs Controller- General of India, the company said it would halt recruitment of volunteers until AstraZeneca finishes evaluation of the safety data.