A LONG ROAD

Vaccine development requires several phases of evaluation to check whether the vaccine is safe and effective

PRE-CLINICAL STAGE

In this, the vaccine is given to animals such as rhesus macaques as the first step to determine safety as well as efficacy. In this, judging efficacy is quicker because the animals can then be exposed to the actual pathogen. Whether they develop the disease is a clear indicatory of efficacy

HUMAN TRIALS

PHASE 1: This is a stage of research that focuses on the safety of a drug. It’s conducted with healthy volunteers, and goal is simply to determine the drug's most frequent and serious side effects. This usually involve a small number of participants PHASE 2: This is the first of the phases to test efficacy. This process begins usually with health volunteers between 18 and 50. The process is often split further depending on how large the trial groups become

PHASE 3: This is the most crucial phase of the trials, where large groups are used. These trials involve doubleblinding and randomisation throughout the large groups in which some will be given the vaccine and some placebos. The objective is to determine enough data that will establish efficacy and rule out external factors

HOW LONG EXACTLY?

On average, it takes 10.71 years from pre-clinical phase to entering the market, according to study in journal PLOS One.

In pandemic situations, with expedited processes, this is expected to take about 12-18 months

WHAT NEEDS TIME

RECRUITMENT: Getting volunteers, especially for phase 2 and phase 3, is a painstaking process. The pools need to be diverse, and yet conform to specification of trials. For example, scientists will check whether people have some other disease that could interfere with the disease. After recruitment, they need to be divided into groups that will get different doses or placebos.

JUDGING EFFICACY: While signs of an immune response become evident soon, the stage of determining whether the vaccine was truly able to make a person immune to the virus will take time – often, researchers track volunteers for a year. This is because people need to naturally be exposed to the virus and scientific ethics prohibit deliberately exposing someone to the virus

DATA ANALYSIS: Preliminary data on whether a vaccine is working is possible within 3-4 months. For instance, researchers involved in the Oxford vaccine said first indications could come by July or August. However, complete data analysis – necessary to rule out misleading values – will take more time