Abstract: Coronavirus disease 2019 (COVID-19) is currently resulted as a worldwide pandemic. It is caused by SARS-CoV-2. A COVID-19 vaccine is intended to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS CoV 2). The objective of this paper is to define the severity and the intensity of adverse reaction for Covid-19 mRNA vaccines. Based on the dataset collected, how many of them got mild reactions, moderate and severe for each mRNA vaccine. 92.30% of them face severe symptoms after using Pfizer-BioNTech vaccine. 100% chance of people experience severe symptoms after using Moderna vaccine. There are slight changes in number of them face severe symptoms from these two mRNA vaccines. By using multi-class classification, found that comparatively Moderna give more adverse reactions than Pfizer-BioNTech.

Keywords: Machine Learning, Covid-19, Adverse Drug Reaction, Pfizer-BioNTech vaccine, Moderna Vaccine, Multi-class Classification.

| DOI: 10.17148/IARJSET.2021.8403