1 Centre for Research in Molecular Modeling, Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke Street W, Montreal, QC, H4B1R6, Canada. gurudeeban.selvaraj@concordia.ca.
2 Centre for Research in Molecular Modeling, Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke Street W, Montreal, QC, H4B1R6, Canada.
3 The State Key Laboratory of Microbial Metabolism, College of Life Sciences and Biotechnology, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang, Shanghai, 200240, China. dqwei@sjtu.edu.cn.
4 IASIA (International Association of Scientists in the Interdisciplinary Areas), 125 Boul. de Bromont, Quebec, QC, J2L 2K7, Canada. dqwei@sjtu.edu.cn.

The Food and Drug Administration (FDA) has recently authorized the two messenger RNA (mRNA) vaccines BNT162b2 and mRNA-1273 for emergency use against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing the COVID-19 coronavirus disease. BNT162b2 and mRNA-1273 vaccines were developed by Pfizer-BioNTech and Moderna, respectively, in 2020. The United Kingdom, Bahrain, Canada, Mexico, United States, Singapore, Oman, Saudi Arabia, Kuwait, and European Union began their vaccination programs with the BNT162b2 vaccine, while the United States and Canada also started the mRNA-1273 vaccination program in mid December 2020. On 28th December 2020, studies reported severe allergic reactions in people who received the BNT162b2, and few people who received the mRNA-1273 vaccine. Authors of the letter thus attempt to explore possible causes of anaphylaxis following COVID-19 vaccination.