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