Scientists explain possible causes of anaphylaxis following mRNA COVID-19 vaccination In an effort to stem the spread of the coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogen, vaccination efforts have been implemented in most countries. Two of the novel vaccines developed to prevent SARS-CoV-2 infection are the novel messenger ribonucleic acid (mRNA) vaccines: the Pfizer-BioNTech (BNT162b2) and the Moderna (mRNA-1273) vaccines. Despite this vaccine type's novelty, mRNA vaccines have been studied by scientists for decades. Moreover, both vaccines underwent extensive testing and rigorous clinical trials to determine their safety and efficacy. Against the backdrop of a global public health emergency, clinical trials and regulatory body approval for both mRNA vaccines had been compressed into a shorter space of time than usual for novel pharmaceuticals like these. However, no safety measures had been compromised in the process, and all of the usual protocols were still undertaken within this expedited timeframe.