Assessing the physicochemical stability and intracellular trafficking of mRNA-based COVID-19 vaccines

: The emergence of SARS-CoV-2 in Wuhan, China in 2019 has had a profound impact on humanity in every facet. While vaccines against this viral pathogen have been approved a year later, limitations to this therapeutic intervention persist, such as drug sensitivity to transportation and storage conditions, as well as significant financial losses from non-injected resuspended vials. Our research delves into the effects of thermal denaturation (4 - 40 °C) and light irradiation (720 and 10460 kJ/m2) on the mRNA-based vaccines BNT162b2 from BioNTech/Pfizer and mRNA-1273 from Moderna. We also investigated vaccine stability following incubation in syringes to simulate potential interactions with silicon oil. By assaying the effects of these stressors via biochemical and biophysical methods, we aim to elucidate the physicochemical properties, integrity, and stability of these mRNA-based vaccines. Furthermore, the incorporation of a fluorophore into both vaccines allowed us to monitor their localization within cells and assess their capacity to evade vesicular transport mechanisms, thus evaluating the differences between the two formulations. A comprehensive understanding of the aforementioned attributes can enable the establishment of optimal storage and manipulation conditions for these vaccines, thereby ensuring their safe and efficacious application while minimizing the waste of functional and safe therapeutic agents.