Comparing the safety of COVID-19 vaccines: a geometrical approach

The prompt development of multiple vaccines for the immunization against the world-wide spread of the COVID-19 infection has raised the issue of comparison of their efficacy and of symptomatic effects on the population treated. The different trial reports, made available from the vaccine producers and from the regulatory authorities, analyze some selected systemic reactions reported from patients after the doses received, these are given in a graded scale. In this contribute we propose a geometric way to compare frequency distributions of categorical variables by introducing a distance measure from the best possible scenario in this repartition. The measure proposed is suitable for a direct comparison among the vaccines in terms of the severity of symptomatic reactions.