Reporting and interpreting the numerical results of a vaccine trial: a practical guide for students and health care professionals

In one year, the COVID pandemic has changed the world. Universities, pharmaceutical companies, and many other organisations worldwide worked effortlessly to develop vaccines to ease the socioeconomic burden of the disease and improve global health care. Nowadays, vaccine efficacy is a very popular term; but do we know what it means and how to calculate it? This article provides information on reporting and interpreting the numerical results of a vaccine trial. It aims to be a practical guide for students and health care professionals. It gives a simple definition of the common terminology, the vaccine efficacy, how to calculate it, and how the confidence interval can be found (though formulae for the latter are not given here). Additionally, it provides two simple examples (A, B), including the formulae for calculating the vaccine efficacy explaining the differences of vaccine efficacy between the two examples simply and pragmatically.