“Messenger RNA (mRNA) as a means for passive immunization has been extensively studied for years. Early studies since the 1990s showed that exogenous mRNA could direct protein expression in vivo, cementing mRNA as a promising drug platform technology , . Several studies later demonstrated the utility of mRNA in vaccine development and conferring protection against cancers  and infectious diseases , . Moreover, passive mRNA immunization also experiences fewer safety issues due to its non‐integrative and transient nature , the latter of which contributes to better and/or easier control of protein expression.
“The potential role of mRNA vaccination in the fight against SARS-CoV-2 is evidenced by ongoing COVID-19 Phase I vaccine trials conducted by several pharmaceutical companies, including Moderna Therapeutics’ mRNA-1273 vaccine , , which has yielding promising results. The feasibility of inhaled RNA for passive transfection has also been proven in a number of studies . On a mechanistic level, the inhaled RNA may lead to passive synthesis of non-infectious spike proteins using cell transfection machinery, hence leading to immunization of the individual.
“Though there are no conclusive or ongoing large scale clinical studies yet to prove the above hypothesis, we believe this proposal is worth exploring in our battle against COVID-19, given the significant number of already recovered individuals and the natural shedding of nonviable SARS-CoV-2 particles in the environment.”